1
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Li Z, Coote JM, Subburaman S, Iacoviello F, Page K, Alles EJ, Prokopovich P, Parkin IP, Desjardins AE, Noimark S. Low-Field Actuating Magnetic Elastomer Membranes Characterized using Fibre-Optic Interferometry. Adv Funct Mater 2023; 33:2301857. [PMID: 38495320 PMCID: PMC10941700 DOI: 10.1002/adfm.202301857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 08/28/2023] [Indexed: 03/19/2024]
Abstract
Smart robotic devices remotely powered by magnetic field have emerged as versatile tools for wide biomedical applications. Soft magnetic elastomer (ME) composite membranes with high flexibility and responsiveness are frequently incorporated to enable local actuation for wireless sensing or cargo delivery. However, the fabrication of thin ME membranes with good control in geometry and uniformity remains challenging, as well as the optimization of their actuating performances under low fields (milli-Tesla). In this work, the development of ME membranes comprising of low-cost magnetic powder and highly soft elastomer through a simple template-assisted doctor blading approach, is reported. The fabricated ME membranes are controllable in size (up to centimetre-scale), thickness (tens of microns) and high particle loading (up to 70 wt.%). Conflicting trade-off effects of particle concentration upon magnetic responsiveness and mechanical stiffness are investigated and found to be balanced off as it exceeds 60 wt.%. A highly sensitive fibre-optic interferometric sensing system and a customized fibre-ferrule-membrane probe are first proposed to enable dynamic actuation and real-time displacement characterization. Free-standing ME membranes are magnetically excited under low field down to 2 mT, and optically monitored with nanometer accuracy. The fast and consistent responses of ME membranes showcase their promising biomedical applications in nanoscale actuation and sensing.
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Affiliation(s)
- Zhi Li
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTUK
- Wellcome / EPSRC Centre for Interventional and Surgical SciencesUniversity College LondonLondonW1W 7TYUK
| | - Joanna. M. Coote
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTUK
- Wellcome / EPSRC Centre for Interventional and Surgical SciencesUniversity College LondonLondonW1W 7TYUK
| | - Swathika Subburaman
- School of Pharmacy and Pharmaceutical SciencesCardiff UniversityCardiffCF10 3NBUK
| | - Francesco Iacoviello
- Electrochemical Innovation LabDepartment of Chemical EngineeringUniversity College LondonLondonWC1E 7JEUK
| | - Kristopher Page
- Department of ChemistryUniversity College LondonLondonWC1H 0AJUK
| | - Erwin J. Alles
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTUK
- Wellcome / EPSRC Centre for Interventional and Surgical SciencesUniversity College LondonLondonW1W 7TYUK
| | - Polina Prokopovich
- School of Pharmacy and Pharmaceutical SciencesCardiff UniversityCardiffCF10 3NBUK
| | - Ivan P. Parkin
- Department of ChemistryUniversity College LondonLondonWC1H 0AJUK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTUK
- Wellcome / EPSRC Centre for Interventional and Surgical SciencesUniversity College LondonLondonW1W 7TYUK
| | - Sacha Noimark
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTUK
- Wellcome / EPSRC Centre for Interventional and Surgical SciencesUniversity College LondonLondonW1W 7TYUK
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2
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Lewis-Thompson I, Zhang EZ, Beard PC, Desjardins AE, Colchester RJ. All-optical ultrasound catheter for rapid B-mode oesophageal imaging. Biomed Opt Express 2023; 14:4052-4064. [PMID: 37799692 PMCID: PMC10549740 DOI: 10.1364/boe.494878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 06/30/2023] [Accepted: 06/30/2023] [Indexed: 10/07/2023]
Abstract
All-optical ultrasound (OpUS) is an imaging paradigm that uses light to both generate and receive ultrasound, and has progressed from benchtop to in vivo studies in recent years, demonstrating promise for minimally invasive surgical applications. In this work, we present a rapid pullback imaging catheter for side-viewing B-mode ultrasound imaging within the upper gastrointestinal tract. The device comprised an ultrasound transmitter configured to generate ultrasound laterally from the catheter and a plano-concave microresonator for ultrasound reception. This imaging probe was capable of generating ultrasound pressures in excess of 1 MPa with corresponding -6 dB bandwidths > 20 MHz. This enabled imaging resolutions as low as 45 µm and 120 µm in the axial and lateral extent respectively, with a corresponding signal-to-noise ratio (SNR) of 42 dB. To demonstrate the potential of the device for clinical imaging, an ex vivo swine oesophagus was imaged using the working channel of a mock endoscope for device delivery. The full thickness of the oesophagus was resolved and several tissue layers were present in the resulting ultrasound images. This work demonstrates the promise for OpUS to provide rapid diagnostics and guidance alongside conventional endoscopy.
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Affiliation(s)
- India Lewis-Thompson
- Department of Medical Physics and
Biomedical Engineering,
University College London, Gower Street, London, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional
and Surgical Sciences,
University College London, Charles Bell House, Foley Street, London, W1W 7TY, UK
| | - Edward Z. Zhang
- Department of Medical Physics and
Biomedical Engineering,
University College London, Gower Street, London, WC1E 6BT, UK
| | - Paul C. Beard
- Department of Medical Physics and
Biomedical Engineering,
University College London, Gower Street, London, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional
and Surgical Sciences,
University College London, Charles Bell House, Foley Street, London, W1W 7TY, UK
| | - Adrien E. Desjardins
- Department of Medical Physics and
Biomedical Engineering,
University College London, Gower Street, London, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional
and Surgical Sciences,
University College London, Charles Bell House, Foley Street, London, W1W 7TY, UK
| | - Richard J. Colchester
- Department of Medical Physics and
Biomedical Engineering,
University College London, Gower Street, London, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional
and Surgical Sciences,
University College London, Charles Bell House, Foley Street, London, W1W 7TY, UK
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3
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Zhang S, Bodian S, Zhang EZ, Beard PC, Noimark S, Desjardins AE, Colchester RJ. Miniaturised dual-modality all-optical ultrasound probe for laser interstitial thermal therapy (LITT) monitoring. Biomed Opt Express 2023; 14:3446-3457. [PMID: 37497509 PMCID: PMC10368049 DOI: 10.1364/boe.494892] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 06/09/2023] [Accepted: 06/13/2023] [Indexed: 07/28/2023]
Abstract
All-optical ultrasound (OpUS) has emerged as an imaging paradigm well-suited to minimally invasive imaging due to its ability to provide high resolution imaging from miniaturised fibre optic devices. Here, we report a fibre optic device capable of concurrent laser interstitial thermal therapy (LITT) and real-time in situ all-optical ultrasound imaging for lesion monitoring. The device comprised three optical fibres: one each for ultrasound transmission, reception and thermal therapy light delivery. This device had a total lateral dimension of <1 mm and was integrated into a medical needle. Simultaneous LITT and monitoring were performed on ex vivo lamb kidney with lesion depth tracked using M-mode OpUS imaging. Using one set of laser energy parameters for LITT (5 W, 60 s), the lesion depth varied from 3.3 mm to 8.3 mm. In all cases, the full lesion depth could be visualised and measured with the OpUS images and there was a good statistical agreement with stereomicroscope images acquired after ablation (t=1.36, p=0.18). This work demonstrates the feasibility and potential of OpUS to guide LITT in tumour resection.
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Affiliation(s)
- Shaoyan Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, Charles Bell House, University College London, 43-45 Foley Street, London W1W 7TY, UK
| | - Semyon Bodian
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, Charles Bell House, University College London, 43-45 Foley Street, London W1W 7TY, UK
- Materials Chemistry Centre, Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK
| | - Edward Z. Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
| | - Paul C. Beard
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, Charles Bell House, University College London, 43-45 Foley Street, London W1W 7TY, UK
| | - Sacha Noimark
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, Charles Bell House, University College London, 43-45 Foley Street, London W1W 7TY, UK
- Materials Chemistry Centre, Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, Charles Bell House, University College London, 43-45 Foley Street, London W1W 7TY, UK
| | - Richard J. Colchester
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, Charles Bell House, University College London, 43-45 Foley Street, London W1W 7TY, UK
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4
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Mathews SJ, Little C, Zhang E, Beard P, Mastracci T, Rakhit R, Desjardins AE. Bend-insensitive fiber optic ultrasonic tracking probe for cardiovascular interventions. Med Phys 2023; 50:3490-3497. [PMID: 36842082 PMCID: PMC10615325 DOI: 10.1002/mp.16334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 02/13/2023] [Accepted: 02/18/2023] [Indexed: 02/27/2023] Open
Abstract
BACKGROUND Transesophageal echocardiography (TEE) is widely used to guide medical device placement in minimally invasive cardiovascular procedures. However, visualization of the device tip with TEE can be challenging. Ultrasonic tracking, enabled by an integrated fiber optic ultrasound sensor (FOUS) that receives transmissions from the TEE probe, is very well suited to improving device localization in this context. The problem addressed in this study is that tight deflections of devices such as a steerable guide catheter can result in bending of the FOUS beyond its specifications and a corresponding loss of ultrasound sensitivity. PURPOSE A bend-insensitive FOUS was developed, and its utility with ultrasonic tracking of a steerable tip during TEE-based image guidance was demonstrated. METHODS Fiberoptic ultrasound sensors were fabricated using both standard and bend insensitive single mode fibers and subjected to static bending at the distal end. The interference transfer function and ultrasound sensitivities were compared for both types of FOUS. The bend-insensitive FOUS was integrated within a steerable guide catheter, which served as an exemplar device; the signal-to-noise ratio (SNR) of tracking signals from the catheter tip with a straight and a fully deflected distal end were measured in a cardiac ultrasound phantom for over 100 frames. RESULTS With tight bending at the distal end (bend radius < 10 mm), the standard FOUS experienced a complete loss of US sensitivity due to high attenuation in the fiber, whereas the bend-insensitive FOUS had largely unchanged performance, with a SNR of 47.7 for straight fiber and a SNR of 36.8 at a bend radius of 3.0 mm. When integrated into the steerable guide catheter, the mean SNRs of the ultrasonic tracking signals recorded with the catheter in a cardiac phantom were similar for straight and fully deflected distal ends: 195 and 163. CONCLUSION The FOUS fabricated from bend-insensitive fiber overcomes the bend restrictions associated with the FOUS fabricated from standard single mode fiber, thereby enabling its use in ultrasonic tracking in a wide range of cardiovascular devices.
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Affiliation(s)
- Sunish J. Mathews
- Wellcome/EPSRC Centre for Interventional and Surgical SciencesUniversity College LondonLondonUK
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Callum Little
- Department of CardiologyImperial College Healthcare NHS Foundation TrustLondonUK
| | - Edward Zhang
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Paul Beard
- Wellcome/EPSRC Centre for Interventional and Surgical SciencesUniversity College LondonLondonUK
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Tara Mastracci
- Department of CardiologyRoyal Free London NHS Foundation TrustLondonUK
| | - Roby Rakhit
- Department of CardiologyRoyal Free London NHS Foundation TrustLondonUK
| | - Adrien E. Desjardins
- Wellcome/EPSRC Centre for Interventional and Surgical SciencesUniversity College LondonLondonUK
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
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5
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Aytac Kipergil E, Martin E, Mathews SJ, Papakonstantinou I, Alles EJ, Desjardins AE. Fiber-optic hydrophone for detection of high-intensity ultrasound waves. Opt Lett 2023; 48:2615-2618. [PMID: 37186722 PMCID: PMC10575604 DOI: 10.1364/ol.488862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 04/06/2023] [Accepted: 04/13/2023] [Indexed: 05/17/2023]
Abstract
Fiber-optic hydrophones (FOHs) are widely used to detect high-intensity focused ultrasound (HIFU) fields. The most common type consists of an uncoated single-mode fiber with a perpendicularly cleaved end face. The main disadvantage of these hydrophones is their low signal-to-noise ratio (SNR). To increase the SNR, signal averaging is performed, but the associated increased acquisition times hinder ultrasound field scans. In this study, with a view to increasing SNR while withstanding HIFU pressures, the bare FOH paradigm is extended to include a partially reflective coating on the fiber end face. Here, a numerical model based on the general transfer-matrix method was implemented. Based on the simulation results, a single-layer, 172 nm TiO2-coated FOH was fabricated. The frequency range of the hydrophone was verified from 1 to 30 MHz. The SNR of the acoustic measurement with the coated sensor was 21 dB higher than that of the uncoated one. The coated sensor successfully withstood a peak positive pressure of 35 MPa for 6000 pulses.
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Affiliation(s)
- Esra Aytac Kipergil
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Charles Bell House, University College London, 43–45 Foley Street, London W1W 7TY, UK
| | - Eleanor Martin
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Charles Bell House, University College London, 43–45 Foley Street, London W1W 7TY, UK
| | - Sunish J. Mathews
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Charles Bell House, University College London, 43–45 Foley Street, London W1W 7TY, UK
| | - Ioannis Papakonstantinou
- Photonic Innovations Lab, Department of Electronic and Electrical Engineering, University College London, Roberts Building, London WC1E 7JE, UK
| | - Erwin J. Alles
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Charles Bell House, University College London, 43–45 Foley Street, London W1W 7TY, UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Charles Bell House, University College London, 43–45 Foley Street, London W1W 7TY, UK
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6
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Baker C, Xochicale M, Lin FY, Mathews S, Joubert F, Shakir DI, Miles R, Mosse CA, Zhao T, Liang W, Kunpalin Y, Dromey B, Mistry T, Sebire NJ, Zhang E, Ourselin S, Beard PC, David AL, Desjardins AE, Vercauteren T, Xia W. Intraoperative Needle Tip Tracking with an Integrated Fibre-Optic Ultrasound Sensor. Sensors (Basel) 2022; 22:9035. [PMID: 36501738 PMCID: PMC9739176 DOI: 10.3390/s22239035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 06/17/2023]
Abstract
Ultrasound is an essential tool for guidance of many minimally-invasive surgical and interventional procedures, where accurate placement of the interventional device is critical to avoid adverse events. Needle insertion procedures for anaesthesia, fetal medicine and tumour biopsy are commonly ultrasound-guided, and misplacement of the needle may lead to complications such as nerve damage, organ injury or pregnancy loss. Clear visibility of the needle tip is therefore critical, but visibility is often precluded by tissue heterogeneities or specular reflections from the needle shaft. This paper presents the in vitro and ex vivo accuracy of a new, real-time, ultrasound needle tip tracking system for guidance of fetal interventions. A fibre-optic, Fabry-Pérot interferometer hydrophone is integrated into an intraoperative needle and used to localise the needle tip within a handheld ultrasound field. While previous, related work has been based on research ultrasound systems with bespoke transmission sequences, the new system-developed under the ISO 13485 Medical Devices quality standard-operates as an adjunct to a commercial ultrasound imaging system and therefore provides the image quality expected in the clinic, superimposing a cross-hair onto the ultrasound image at the needle tip position. Tracking accuracy was determined by translating the needle tip to 356 known positions in the ultrasound field of view in a tank of water, and by comparison to manual labelling of the the position of the needle in B-mode US images during an insertion into an ex vivo phantom. In water, the mean distance between tracked and true positions was 0.7 ± 0.4 mm with a mean repeatability of 0.3 ± 0.2 mm. In the tissue phantom, the mean distance between tracked and labelled positions was 1.1 ± 0.7 mm. Tracking performance was found to be independent of needle angle. The study demonstrates the performance and clinical compatibility of ultrasound needle tracking, an essential step towards a first-in-human study.
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Affiliation(s)
- Christian Baker
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Miguel Xochicale
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Fang-Yu Lin
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Sunish Mathews
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London W1W 7TY, UK
| | - Francois Joubert
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Dzhoshkun I. Shakir
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Richard Miles
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Charles A. Mosse
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London W1W 7TY, UK
| | - Tianrui Zhao
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Weidong Liang
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Yada Kunpalin
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London W1W 7TY, UK
- Elizabeth Garrett Anderson Institute for Women’s Health, University College London, 74 Huntley Street, London WC1E 6AU, UK
| | - Brian Dromey
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London W1W 7TY, UK
- Elizabeth Garrett Anderson Institute for Women’s Health, University College London, 74 Huntley Street, London WC1E 6AU, UK
| | - Talisa Mistry
- NIHR Great Ormond Street BRC and Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
| | - Neil J. Sebire
- NIHR Great Ormond Street BRC and Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
| | - Edward Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London W1W 7TY, UK
| | - Sebastien Ourselin
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Paul C. Beard
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London W1W 7TY, UK
| | - Anna L. David
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London W1W 7TY, UK
- Elizabeth Garrett Anderson Institute for Women’s Health, University College London, 74 Huntley Street, London WC1E 6AU, UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London W1W 7TY, UK
| | - Tom Vercauteren
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Wenfeng Xia
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing, St Thomas’ Hospital, London SE1 7EH, UK
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7
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Shi M, Bodian S, West SJ, Sathasivam S, Gordon RJ, Collier P, Vercauteren T, Desjardins AE, Noimark S, Xia W. Enhanced Photoacoustic Visualisation of Clinical Needles by Combining Interstitial and Extracorporeal Illumination of Elastomeric Nanocomposite Coatings. Sensors (Basel) 2022; 22:6417. [PMID: 36080876 PMCID: PMC9460224 DOI: 10.3390/s22176417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/18/2022] [Accepted: 08/23/2022] [Indexed: 06/15/2023]
Abstract
Ultrasound (US) image guidance is widely used for minimally invasive procedures, but the invasive medical devices (such as metallic needles), especially their tips, can be poorly visualised in US images, leading to significant complications. Photoacoustic (PA) imaging is promising for visualising invasive devices and peripheral tissue targets. Light-emitting diodes (LEDs) acting as PA excitation sources facilitate the clinical translation of PA imaging, but the image quality is degraded due to the low pulse energy leading to insufficient contrast with needles at deep locations. In this paper, photoacoustic visualisation of clinical needles was enhanced by elastomeric nanocomposite coatings with superficial and interstitial illumination. Candle soot nanoparticle-polydimethylsiloxane (CSNP-PDMS) composites with high optical absorption and large thermal expansion coefficients were applied onto the needle exterior and the end-face of an optical fibre placed in the needle lumen. The excitation light was delivered at the surface by LED arrays and through the embedded optical fibre by a pulsed diode laser to improve the visibility of the needle tip. The performance was validated using an ex-vivo tissue model. An LED-based PA/US imaging system was used for imaging the needle out-of-plane and in-plane insertions over approach angles of 20 deg to 55 deg. The CSNP-PDMS composite conferred substantial visual enhancements on both the needle shaft and the tip, with an average of 1.7- and 1.6-fold improvements in signal-to-noise ratios (SNRs), respectively. With the extended light field involving extracorporeal and interstitial illumination and the highly absorbing coatings, enhanced visualisation of the needle shaft and needle tip was achieved with PA imaging, which could be helpful in current US-guided minimally invasive surgeries.
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Affiliation(s)
- Mengjie Shi
- School of Biomedical Engineering and Imaging Sciences, King’s College London, London SE1 7EH, UK
| | - Semyon Bodian
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London W1W 7TY, UK
| | - Simeon J. West
- Department of Anaesthesia, University College Hospital, London NW1 2BU, UK
| | - Sanjayan Sathasivam
- Department of Chemistry, University College London, London WC1H 0AJ, UK or
- School of Engineering, London South Bank University, London SE1 0AA, UK
| | | | - Paul Collier
- Johnson Matthey Technology Centre, Reading RG4 9NH, UK
| | - Tom Vercauteren
- School of Biomedical Engineering and Imaging Sciences, King’s College London, London SE1 7EH, UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London W1W 7TY, UK
| | - Sacha Noimark
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London W1W 7TY, UK
| | - Wenfeng Xia
- School of Biomedical Engineering and Imaging Sciences, King’s College London, London SE1 7EH, UK
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8
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Colchester RJ, Zhang EZ, Beard PC, Desjardins AE. High-resolution sub-millimetre diameter side-viewing all-optical ultrasound transducer based on a single dual-clad optical fibre. Biomed Opt Express 2022; 13:4047-4057. [PMID: 35991929 PMCID: PMC9352281 DOI: 10.1364/boe.459486] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 05/13/2022] [Accepted: 05/13/2022] [Indexed: 05/31/2023]
Abstract
All-optical ultrasound (OpUS), where ultrasound is both generated and received using light, has emerged as a modality well-suited to highly miniaturised applications. In this work we present a proof-of-concept OpUS transducer built onto a single optical fibre with a highly miniaturised lateral dimension (<0.8 mm). A key innovation was to use a dual-clad optical fibre (DCF) to provide multimode light for ultrasound generation and single mode light for ultrasound reception. The transducer comprised a proximal section of DCF spliced to a short section of single mode fibre (SMF). Multimode light was outcoupled at the splice joint and guided within a square capillary to provide excitation for ultrasound generation. Whilst single mode light was guided to the distal tip of the SMF to a plano-concave microresonator for ultrasound reception. The device was capable of generating ultrasound with pressures >0.4 MPa and a corresponding bandwidth >27 MHz. Concurrent ultrasound generation and reception from the transducer enabled imaging via motorised pull-back allowing image acquisition times of 4 s for an aperture of 20 mm. Image resolution was as low as ~50 µm and 190 µm in the axial and lateral extents, respectively, without the need for image reconstruction. Porcine aorta was imaged ex vivo demonstrating detailed ultrasound images. The unprecedented level of miniaturisation along with the high image quality produced by this device represents a radical new paradigm for minimally invasive imaging.
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Affiliation(s)
- Richard J. Colchester
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, 43-45 Foley Street, London, W1W 7TY, UK
| | - Edward Z. Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, 43-45 Foley Street, London, W1W 7TY, UK
| | - Paul C. Beard
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, 43-45 Foley Street, London, W1W 7TY, UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, 43-45 Foley Street, London, W1W 7TY, UK
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9
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Lewis-Thompson I, Zhang S, Noimark S, Desjardins AE, Colchester RJ. PDMS composites with photostable NIR dyes for multi-modal ultrasound imaging. MRS Advances 2022; 7:499-503. [PMID: 35694205 PMCID: PMC9174115 DOI: 10.1557/s43580-022-00208-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 12/27/2021] [Indexed: 02/07/2023]
Abstract
Abstract All-optical ultrasound (OpUS) imaging has emerged as an imaging paradigm well-suited for minimally invasive surgical procedures. With this modality, ultrasound is generated when pulsed or modulated light is absorbed within a coating material. By engineering wavelength-selective coatings, complementary imaging and therapeutic modalities can be integrated with OpUS. Here, we present a wavelength-selective composite material comprising a near-infrared absorbing dye and polydimethylsiloxane. The optical absorption for this material peaked in the vicinity of 1064 nm, with up to 91% of incident light being absorbed, whilst maintaining lower optical absorption at other wavelengths. This material was used to generate ultrasound, demonstrating ultrasound pressures \documentclass[12pt]{minimal}
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\begin{document}$$<10$$\end{document}<10%), longer than required for standard clinical imaging applications. Graphical abstract ![]()
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Affiliation(s)
- India Lewis-Thompson
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, Foley Street, London, W1W 7TY UK
| | - Shaoyan Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, Foley Street, London, W1W 7TY UK
| | - Sacha Noimark
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, Foley Street, London, W1W 7TY UK
- Materials Chemistry Centre, Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, Foley Street, London, W1W 7TY UK
| | - Richard J. Colchester
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, Foley Street, London, W1W 7TY UK
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10
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Shi M, Zhao T, West SJ, Desjardins AE, Vercauteren T, Xia W. Improving needle visibility in LED-based photoacoustic imaging using deep learning with semi-synthetic datasets. Photoacoustics 2022; 26:100351. [PMID: 35495095 PMCID: PMC9048160 DOI: 10.1016/j.pacs.2022.100351] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 03/29/2022] [Accepted: 03/30/2022] [Indexed: 06/14/2023]
Abstract
Photoacoustic imaging has shown great potential for guiding minimally invasive procedures by accurate identification of critical tissue targets and invasive medical devices (such as metallic needles). The use of light emitting diodes (LEDs) as the excitation light sources accelerates its clinical translation owing to its high affordability and portability. However, needle visibility in LED-based photoacoustic imaging is compromised primarily due to its low optical fluence. In this work, we propose a deep learning framework based on U-Net to improve the visibility of clinical metallic needles with a LED-based photoacoustic and ultrasound imaging system. To address the complexity of capturing ground truth for real data and the poor realism of purely simulated data, this framework included the generation of semi-synthetic training datasets combining both simulated data to represent features from the needles and in vivo measurements for tissue background. Evaluation of the trained neural network was performed with needle insertions into blood-vessel-mimicking phantoms, pork joint tissue ex vivo and measurements on human volunteers. This deep learning-based framework substantially improved the needle visibility in photoacoustic imaging in vivo compared to conventional reconstruction by suppressing background noise and image artefacts, achieving 5.8 and 4.5 times improvements in terms of signal-to-noise ratio and the modified Hausdorff distance, respectively. Thus, the proposed framework could be helpful for reducing complications during percutaneous needle insertions by accurate identification of clinical needles in photoacoustic imaging.
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Affiliation(s)
- Mengjie Shi
- School of Biomedical Engineering and Imaging Sciences, King’s College London, London SE1 7EH, United Kingdom
| | - Tianrui Zhao
- School of Biomedical Engineering and Imaging Sciences, King’s College London, London SE1 7EH, United Kingdom
| | - Simeon J. West
- Department of Anaesthesia, University College Hospital, London NW1 2BU, United Kingdom
| | - Adrien E. Desjardins
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London W1 W 7TY, United Kingdom
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - Tom Vercauteren
- School of Biomedical Engineering and Imaging Sciences, King’s College London, London SE1 7EH, United Kingdom
| | - Wenfeng Xia
- School of Biomedical Engineering and Imaging Sciences, King’s College London, London SE1 7EH, United Kingdom
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11
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Little CD, Mackle EC, Maneas E, Chong D, Nikitichev D, Constantinou J, Tsui J, Hamilton G, Rakhit RD, Mastracci TM, Desjardins AE. A patient-specific multi-modality abdominal aortic aneurysm imaging phantom. Int J Comput Assist Radiol Surg 2022; 17:1611-1617. [PMID: 35397710 PMCID: PMC9463301 DOI: 10.1007/s11548-022-02612-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 03/15/2022] [Indexed: 11/29/2022]
Abstract
Purpose Multimodality imaging of the vascular system is a rapidly growing area of innovation and research, which is increasing with awareness of the dangers of ionizing radiation. Phantom models that are applicable across multiple imaging modalities facilitate testing and comparisons in pre-clinical studies of new devices. Additionally, phantom models are of benefit to surgical trainees for gaining experience with new techniques. We propose a temperature-stable, high-fidelity method for creating complex abdominal aortic aneurysm phantoms that are compatible with both radiation-based, and ultrasound-based imaging modalities, using low cost materials. Methods Volumetric CT data of an abdominal aortic aneurysm were acquired. Regions of interest were segmented to form a model compatible with 3D printing. The novel phantom fabrication method comprised a hybrid approach of using 3D printing of water-soluble materials to create wall-less, patient-derived vascular structures embedded within tailored tissue-mimicking materials to create realistic surrounding tissues. A non-soluble 3-D printed spine was included to provide a radiological landmark. Results The phantom was found to provide realistic appearances with intravascular ultrasound, computed tomography and transcutaneous ultrasound. Furthermore, the utility of this phantom as a training model was demonstrated during a simulated endovascular aneurysm repair procedure with image fusion. Conclusion With the hybrid fabrication method demonstrated here, complex multimodality imaging patient-derived vascular phantoms can be successfully fabricated. These have potential roles in the benchtop development of emerging imaging technologies, refinement of novel minimally invasive surgical techniques and as clinical training tools.
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Affiliation(s)
- Callum D Little
- Wellcome Trust-EPSRC Centre for Interventional and Surgical Sciences, London, W1W 7TS, UK
- Department of Medical Physics and Bioengineering, University College London, London, WC1E 6BT, UK
- Department of Cardiology, Royal Free Hospital, London, NW3 2QG, UK
| | - Eleanor C Mackle
- Wellcome Trust-EPSRC Centre for Interventional and Surgical Sciences, London, W1W 7TS, UK
- Department of Medical Physics and Bioengineering, University College London, London, WC1E 6BT, UK
| | - Efthymios Maneas
- Wellcome Trust-EPSRC Centre for Interventional and Surgical Sciences, London, W1W 7TS, UK
- Department of Medical Physics and Bioengineering, University College London, London, WC1E 6BT, UK
| | - Debra Chong
- Wellcome Trust-EPSRC Centre for Interventional and Surgical Sciences, London, W1W 7TS, UK
- Department of Vascular Surgery, Royal Free Hospital, London, NW3 2QG, UK
| | - Daniil Nikitichev
- Wellcome Trust-EPSRC Centre for Interventional and Surgical Sciences, London, W1W 7TS, UK
| | - Jason Constantinou
- Department of Vascular Surgery, Royal Free Hospital, London, NW3 2QG, UK
| | - Janice Tsui
- Wellcome Trust-EPSRC Centre for Interventional and Surgical Sciences, London, W1W 7TS, UK
- Department of Vascular Surgery, Royal Free Hospital, London, NW3 2QG, UK
| | - George Hamilton
- Wellcome Trust-EPSRC Centre for Interventional and Surgical Sciences, London, W1W 7TS, UK
- Department of Vascular Surgery, Royal Free Hospital, London, NW3 2QG, UK
| | - Roby D Rakhit
- Department of Cardiology, Royal Free Hospital, London, NW3 2QG, UK
| | - Tara M Mastracci
- Division of Surgery and Interventional Science, University College London, London, W1W 7TY, UK
| | - Adrien E Desjardins
- Wellcome Trust-EPSRC Centre for Interventional and Surgical Sciences, London, W1W 7TS, UK.
- Department of Medical Physics and Bioengineering, University College London, London, WC1E 6BT, UK.
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12
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Maneas E, Hauptmann A, Alles EJ, Xia W, Vercauteren T, Ourselin S, David AL, Arridge S, Desjardins AE. Deep Learning for Instrumented Ultrasonic Tracking: From Synthetic Training Data to In Vivo Application. IEEE Trans Ultrason Ferroelectr Freq Control 2022; 69:543-552. [PMID: 34748488 DOI: 10.1109/tuffc.2021.3126530] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Instrumented ultrasonic tracking is used to improve needle localization during ultrasound guidance of minimally invasive percutaneous procedures. Here, it is implemented with transmitted ultrasound pulses from a clinical ultrasound imaging probe, which is detected by a fiber-optic hydrophone integrated into a needle. The detected transmissions are then reconstructed to form the tracking image. Two challenges are considered with the current implementation of ultrasonic tracking. First, tracking transmissions are interleaved with the acquisition of B-mode images, and thus, the effective B-mode frame rate is reduced. Second, it is challenging to achieve an accurate localization of the needle tip when the signal-to-noise ratio is low. To address these challenges, we present a framework based on a convolutional neural network (CNN) to maintain spatial resolution with fewer tracking transmissions and enhance signal quality. A major component of the framework included the generation of realistic synthetic training data. The trained network was applied to unseen synthetic data and experimental in vivo tracking data. The performance of needle localization was investigated when reconstruction was performed with fewer (up to eightfold) tracking transmissions. CNN-based processing of conventional reconstructions showed that the axial and lateral spatial resolutions could be improved even with an eightfold reduction in tracking transmissions. The framework presented in this study will significantly improve the performance of ultrasonic tracking, leading to faster image acquisition rates and increased localization accuracy.
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13
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Bodian S, Colchester RJ, Macdonald TJ, Ambroz F, Briceno de Gutierrez M, Mathews SJ, Fong YMM, Maneas E, Welsby KA, Gordon RJ, Collier P, Zhang EZ, Beard PC, Parkin IP, Desjardins AE, Noimark S. CuInS 2 Quantum Dot and Polydimethylsiloxane Nanocomposites for All-Optical Ultrasound and Photoacoustic Imaging. Adv Mater Interfaces 2021; 8:2100518. [PMID: 34777946 PMCID: PMC8573612 DOI: 10.1002/admi.202100518] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 06/28/2021] [Indexed: 05/13/2023]
Abstract
Dual-modality imaging employing complementary modalities, such as all-optical ultrasound and photoacoustic imaging, is emerging as a well-suited technique for guiding minimally invasive surgical procedures. Quantum dots are a promising material for use in these dual-modality imaging devices as they can provide wavelength-selective optical absorption. The first quantum dot nanocomposite engineered for co-registered laser-generated ultrasound and photoacoustic imaging is presented. The nanocomposites developed, comprising CuInS2 quantum dots and medical-grade polydimethylsiloxane (CIS-PDMS), are applied onto the distal ends of miniature optical fibers. The films exhibit wavelength-selective optical properties, with high optical absorption (> 90%) at 532 nm for ultrasound generation, and low optical absorption (< 5%) at near-infrared wavelengths greater than 700 nm. Under pulsed laser irradiation, the CIS-PDMS films generate ultrasound with pressures exceeding 3.5 MPa, with a corresponding bandwidth of 18 MHz. An ultrasound transducer is fabricated by pairing the coated optical fiber with a Fabry-Pérot (FP) fiber optic sensor. The wavelength-selective nature of the film is exploited to enable co-registered all-optical ultrasound and photoacoustic imaging of an ink-filled tube phantom. This work demonstrates the potential for quantum dots as wavelength-selective absorbers for all-optical ultrasound generation.
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Affiliation(s)
- Semyon Bodian
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTUK
- Wellcome/ESPRC Centre for Surgical and Interventional SciencesUniversity College LondonCharles Bell House, 67–73 Riding House StreetLondonW1W 7EJUK
- Materials Chemistry CentreDepartment of ChemistryUniversity College London20 Gordon StreetLondonWC1H 0AJUK
| | - Richard J. Colchester
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTUK
- Wellcome/ESPRC Centre for Surgical and Interventional SciencesUniversity College LondonCharles Bell House, 67–73 Riding House StreetLondonW1W 7EJUK
| | - Thomas J. Macdonald
- Materials Chemistry CentreDepartment of ChemistryUniversity College London20 Gordon StreetLondonWC1H 0AJUK
- Department of Chemistry and Centre for Processable ElectronicsImperial College LondonLondonW12 0BZUK
| | - Filip Ambroz
- Materials Chemistry CentreDepartment of ChemistryUniversity College London20 Gordon StreetLondonWC1H 0AJUK
| | | | - Sunish J. Mathews
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTUK
- Wellcome/ESPRC Centre for Surgical and Interventional SciencesUniversity College LondonCharles Bell House, 67–73 Riding House StreetLondonW1W 7EJUK
| | - Yu Man Mandy Fong
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTUK
- Wellcome/ESPRC Centre for Surgical and Interventional SciencesUniversity College LondonCharles Bell House, 67–73 Riding House StreetLondonW1W 7EJUK
- Materials Chemistry CentreDepartment of ChemistryUniversity College London20 Gordon StreetLondonWC1H 0AJUK
| | - Efthymios Maneas
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTUK
- Wellcome/ESPRC Centre for Surgical and Interventional SciencesUniversity College LondonCharles Bell House, 67–73 Riding House StreetLondonW1W 7EJUK
| | - Kathryn A. Welsby
- Central Laser FacilityHarwell Science and Innovation CampusChiltonDidcotOX11 0DEUK
| | - Ross J. Gordon
- Johnson Matthey Technology CentreSonning CommonReadingRG4 9NHUK
| | - Paul Collier
- Johnson Matthey Technology CentreSonning CommonReadingRG4 9NHUK
| | - Edward Z. Zhang
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTUK
| | - Paul C. Beard
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTUK
- Wellcome/ESPRC Centre for Surgical and Interventional SciencesUniversity College LondonCharles Bell House, 67–73 Riding House StreetLondonW1W 7EJUK
| | - Ivan P. Parkin
- Materials Chemistry CentreDepartment of ChemistryUniversity College London20 Gordon StreetLondonWC1H 0AJUK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTUK
- Wellcome/ESPRC Centre for Surgical and Interventional SciencesUniversity College LondonCharles Bell House, 67–73 Riding House StreetLondonW1W 7EJUK
| | - Sacha Noimark
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTUK
- Wellcome/ESPRC Centre for Surgical and Interventional SciencesUniversity College LondonCharles Bell House, 67–73 Riding House StreetLondonW1W 7EJUK
- Materials Chemistry CentreDepartment of ChemistryUniversity College London20 Gordon StreetLondonWC1H 0AJUK
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14
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Colchester RJ, Little CD, Alles EJ, Desjardins AE. Flexible and directional fibre optic ultrasound transmitters using photostable dyes. OSA Contin 2021; 4:2488-2495. [PMID: 37841369 PMCID: PMC10575603 DOI: 10.1364/osac.431444] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 08/09/2021] [Accepted: 08/11/2021] [Indexed: 10/17/2023]
Abstract
All-optical ultrasound transducers are well-suited for use in imaging during minimally invasive surgical procedures. This requires highly miniaturised and flexible devices. Here we present optical ultrasound transmitters for imaging applications based on modified optical fibre distal tips which allow for larger transmitter element sizes, whilst maintaining small diameter proximal optical fibre. Three optical ultrasound transmitter configurations were compared; a 400 µm core optical fibre, a 200 µm core optical fibre with a 400 µm core optical fibre distal tip, and a 200 µm core optical fibre with a 400 µm core capillary distal tip. All the transmitters used a polydimethylsiloxane-dye composite material for ultrasound generation. The material comprised a photostable infra-red absorbing dye to provide optical absorption for the ultrasound transduction. The generated ultrasound beam profile for the three transmitters was compared, demonstrating similar results, with lateral beam widths <1.7 mm at a depth of 10 mm. The composite material demonstrates a promising alternative to previously reported materials, generating ultrasound pressures exceeding 2 MPa, with corresponding bandwidths ca. 30 MHz. These highly flexible ultrasound transmitters can be readily incorporated into medical devices with small lateral dimensions.
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Affiliation(s)
- Richard J. Colchester
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
- Wellcome/ESPRC Centre for Interventional and Surgical Sciences, 43-45 Foley Street, London, W1W 7TY, UK
| | - Callum D. Little
- Wellcome/ESPRC Centre for Interventional and Surgical Sciences, 43-45 Foley Street, London, W1W 7TY, UK
- Department of Cardiovascular Medicine, Royal Free NHS Foundation Trust, London, UK
| | - Erwin J. Alles
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
- Wellcome/ESPRC Centre for Interventional and Surgical Sciences, 43-45 Foley Street, London, W1W 7TY, UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
- Wellcome/ESPRC Centre for Interventional and Surgical Sciences, 43-45 Foley Street, London, W1W 7TY, UK
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15
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Alles EJ, Mackle EC, Noimark S, Zhang EZ, Beard PC, Desjardins AE. Freehand and video-rate all-optical ultrasound imaging. Ultrasonics 2021; 116:106514. [PMID: 34280811 PMCID: PMC7611777 DOI: 10.1016/j.ultras.2021.106514] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 04/30/2021] [Accepted: 06/30/2021] [Indexed: 06/13/2023]
Abstract
All-optical ultrasound (AOUS) imaging, which uses light to both generate and detect ultrasound, is an emerging alternative to conventional electronic ultrasound imaging. To date, AOUS imaging has been performed using paradigms that either resulted in long acquisition times or employed bench-top imaging systems that were impractical for clinical use. In this work, we present a novel AOUS imaging paradigm where scanning optics are used to rapidly synthesise an imaging aperture. This paradigm enabled the first AOUS system with a flexible, handheld imaging probe, which represents a critical step towards clinical translation. This probe, which provides video-rate imaging and a real-time display, is demonstrated with phantoms and in vivo human tissue.
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Affiliation(s)
- Erwin J Alles
- Department of Medical Physics & Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom; Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 43-45 Foley Street, London W1W 7TS, United Kingdom.
| | - Eleanor C Mackle
- Department of Medical Physics & Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom; Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 43-45 Foley Street, London W1W 7TS, United Kingdom
| | - Sacha Noimark
- Department of Medical Physics & Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom; Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 43-45 Foley Street, London W1W 7TS, United Kingdom
| | - Edward Z Zhang
- Department of Medical Physics & Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom; Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 43-45 Foley Street, London W1W 7TS, United Kingdom
| | - Paul C Beard
- Department of Medical Physics & Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom; Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 43-45 Foley Street, London W1W 7TS, United Kingdom
| | - Adrien E Desjardins
- Department of Medical Physics & Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom; Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 43-45 Foley Street, London W1W 7TS, United Kingdom
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16
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Poduval RK, Coote JM, Mosse CA, Finlay MC, Desjardins AE, Papakonstantinou I. Precision-Microfabricated Fiber-Optic Probe for Intravascular Pressure and Temperature Sensing. IEEE J Sel Top Quantum Electron 2021; 27:7100412. [PMID: 33716587 PMCID: PMC7951063 DOI: 10.1109/jstqe.2021.3054727] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 01/05/2021] [Accepted: 01/21/2021] [Indexed: 05/21/2023]
Abstract
Small form-factor sensors are widely used in minimally invasive intravascular diagnostic procedures. Manufacturing complexities associated with miniaturizing current fiber-optic probes, particularly for multi-parameter sensing, severely constrain their adoption outside of niche fields. It is especially challenging to rapidly prototype and iterate upon sensor designs to optimize performance for medical devices. In this work, a novel technique to construct a microscale extrinsic fiber-optic sensor with a confined air cavity and sub-micron geometric resolution is presented. The confined air cavity is enclosed between a 3 μm thick pressure-sensitive distal diaphragm and a proximal temperature-sensitive plano-convex microlens segment unresponsive to changes in external pressure. Simultaneous pressure and temperature measurements are possible through optical interrogation via phase-resolved low-coherence interferometry (LCI). Upon characterization in a simulated intravascular environment, we find these sensors capable of detecting pressure changes down to 0.11 mmHg (in the range of 760 to 1060 mmHg) and temperature changes of 0.036 °C (in the range 34 to 50 °C). By virtue of these sensitivity values suited to intravascular physiological monitoring, and the scope of design flexibility enabled by the precision-fabricated photoresist microstructure, it is envisaged that this technique will enable construction of a wide range of fiber-optic sensors for guiding minimally invasive medical procedures.
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Affiliation(s)
- Radhika K Poduval
- Department of Electronic and Electrical EngineeringUniversity College LondonLondonWC1E 7JEU.K
| | - Joanna M Coote
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTU.K
| | - Charles A Mosse
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTU.K
| | - Malcolm C Finlay
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTU.K
| | - Adrien E Desjardins
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonWC1E 6BTU.K
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17
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Aytac-Kipergil E, Desjardins AE, Treeby BE, Noimark S, Parkin IP, Alles EJ. Modelling and measurement of laser-generated focused ultrasound: Can interventional transducers achieve therapeutic effects? J Acoust Soc Am 2021; 149:2732. [PMID: 33940866 PMCID: PMC8060049 DOI: 10.1121/10.0004302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 03/05/2021] [Accepted: 03/26/2021] [Indexed: 05/02/2023]
Abstract
Laser-generated focused ultrasound (LGFU) transducers used for ultrasound therapy commonly have large diameters (6-15 mm), but smaller lateral dimensions (<4 mm) are required for interventional applications. To address the question of whether miniaturized LGFU transducers could generate sufficient pressure at the focus to enable therapeutic effects, a modelling and measurement study is performed. Measurements are carried out for both linear and nonlinear propagation for various illumination schemes and compared with the model. The model comprises several innovations. First, the model allows for radially varying acoustic input distributions on the surface of the LGFU transducer, which arise from the excitation light impinging on the curved transducer surfaces. This realistic representation of the source prevents the overestimation of the achievable pressures (shown here to be as high as 1.8 times). Second, an alternative inverse Gaussian illumination paradigm is proposed to achieve higher pressures; a 35% increase is observed in the measurements. Simulations show that LGFU transducers as small as 3.5 mm could generate sufficient peak negative pressures at the focus to exceed the cavitation threshold in water and blood. Transducers of this scale could be integrated with interventional devices, thereby opening new opportunities for therapeutic applications from inside the body.
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Affiliation(s)
- Esra Aytac-Kipergil
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom
| | - Adrien E Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom
| | - Bradley E Treeby
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom
| | - Sacha Noimark
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom
| | - Ivan P Parkin
- Department of Chemistry, Materials Chemistry Research Centre, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Erwin J Alles
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom
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18
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Schneider C, Nikitichev D, Xia W, Gurusamy K, Desjardins AE, Davidson BR. Multispectral tissue mapping: developing a concept for the optical evaluation of liver disease. J Med Imaging (Bellingham) 2020; 7:066001. [PMID: 33376759 PMCID: PMC7757517 DOI: 10.1117/1.jmi.7.6.066001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 12/01/2020] [Indexed: 11/14/2022] Open
Abstract
Purpose: Alterations in the optical absorption behavior of liver tissue secondary to pathological processes can be evaluated by multispectral analysis, which is increasingly being explored as an imaging adjunct for use in liver surgery. Current methods are either invasive or have a limited wavelength spectrum, which restricts utility. This proof of concept study describes the development of a multispectral imaging (MSI) method called multispectral tissue mapping (MTM) that addresses these issues. Approach: The imaging system consists of a tunable excitation light source and a near-infrared camera. Following the development stage, proof of concept experiments are carried out where absorption spectra from colorectal cancer liver metastasis (CRLM), hepatocellular carcinoma (HCC), and liver steatosis specimen are acquired and compared to controls. Absorption spectra are compared to histopathology examination as the current gold standard for tissue assessment. Generalized linear mixed modeling is employed to compare absorption characteristics of individual pixels and to select wavelengths for false color image processing with the aim of visually enhancing cancer tissue. Results: Analysis of individual pixels revealed distinct absorption spectra therefore suggesting that MTM is possible. A prominent absorption peak at 1210 nm was found in lipid-rich animal tissues and steatotic liver specimen. Liver cancer tissue had a heterogeneous appearance on MSI. Subsequent statistical analysis suggests that measuring changes in absorption behavior may be a feasible method to estimate the pixel-based probability of cancer being present. In CRLM, this was observed throughout 1100 to 1700 nm, whereas in HCC it was concentrated around 1140 and 1430 nm. False color image processing visibly enhances contrast between cancer and normal liver tissues. Conclusions: The system's ability to enable no-touch MSI at 1100 to 1700 nm was demonstrated. Preliminary data suggest that MTM warrants further exploration as a potential imaging tool for the detection of liver cancer during surgery.
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Affiliation(s)
- Crispin Schneider
- University College London, Division of Surgery and Interventional Science, Royal Free Campus, London, United Kingdom
| | - Daniil Nikitichev
- University College London, Wellcome/EPSRC Centre for Surgical and Interventional Sciences, London, United Kingdom.,University College London, Department of Medical Physics and Bioengineering, London, United Kingdom
| | - Wenfeng Xia
- University College London, Wellcome/EPSRC Centre for Surgical and Interventional Sciences, London, United Kingdom.,University College London, Department of Medical Physics and Bioengineering, London, United Kingdom
| | - Kurinchi Gurusamy
- University College London, Division of Surgery and Interventional Science, Royal Free Campus, London, United Kingdom.,University College London, Wellcome/EPSRC Centre for Surgical and Interventional Sciences, London, United Kingdom
| | - Adrien E Desjardins
- University College London, Wellcome/EPSRC Centre for Surgical and Interventional Sciences, London, United Kingdom.,University College London, Department of Medical Physics and Bioengineering, London, United Kingdom
| | - Brian R Davidson
- University College London, Division of Surgery and Interventional Science, Royal Free Campus, London, United Kingdom.,University College London, Wellcome/EPSRC Centre for Surgical and Interventional Sciences, London, United Kingdom
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19
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Ansari R, Zhang EZ, Desjardins AE, Beard PC. Miniature all-optical flexible forward-viewing photoacoustic endoscopy probe for surgical guidance. Opt Lett 2020; 45:6238-6241. [PMID: 33186959 PMCID: PMC8219374 DOI: 10.1364/ol.400295] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/17/2020] [Accepted: 08/18/2020] [Indexed: 05/13/2023]
Abstract
A miniature flexible photoacoustic endoscopy probe that provides high-resolution 3D images of vascular structures in the forward-viewing configuration is described. A planar Fabry-Perot ultrasound sensor with a -3dB bandwidth of 53 MHz located at the tip of the probe is interrogated via a flexible fiber bundle and a miniature optical relay system to realize an all-optical probe measuring 7.4 mm in outer diameter at the tip. This approach to photoacoustic endoscopy offers advantages over previous piezoelectric based distal-end scanning probes. These include a forward-viewing configuration in widefield photoacoustic tomography mode, finer spatial sampling (87 µm spatial sampling interval), and wider detection bandwidth (53 MHz) than has been achievable with conventional ultrasound detection technology and an all-optical passive imaging head for safe endoscopic use.
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Affiliation(s)
- Rehman Ansari
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, 43-45 Foley Street, London W1W 7TS, UK
| | - Edward Z. Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, 43-45 Foley Street, London W1W 7TS, UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, 43-45 Foley Street, London W1W 7TS, UK
| | - Paul C. Beard
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, 43-45 Foley Street, London W1W 7TS, UK
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20
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Little CD, Colchester RJ, Noimark S, Manmathan G, Finlay MC, Desjardins AE, Rakhit RD. Optically Generated Ultrasound for Intracoronary Imaging. Front Cardiovasc Med 2020; 7:525530. [PMID: 33173786 PMCID: PMC7591717 DOI: 10.3389/fcvm.2020.525530] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 09/04/2020] [Indexed: 11/13/2022] Open
Abstract
Conventional intravascular ultrasound (IVUS) devices use piezoelectric transducers to electrically generate and receive US. With this paradigm, there are numerous challenges that restrict improvements in image quality. First, with miniaturization of the transducers to reduce device size, it can be challenging to achieve the sensitivities and bandwidths required for large tissue penetration depths and high spatial resolution. Second, complexities associated with manufacturing miniaturized electronic transducers can have significant cost implications. Third, with increasing interest in molecular characterization of tissue in-vivo, it has been challenging to incorporate optical elements for multimodality imaging with photoacoustics (PA) or near-infrared spectroscopy (NIRS) whilst maintaining the lateral dimensions suitable for intracoronary imaging. Optical Ultrasound (OpUS) is a new paradigm for intracoronary imaging. US is generated at the surface of a fiber optic transducer via the photoacoustic effect. Pulsed or modulated light is absorbed in an engineered coating on the fiber surface and converted to thermal energy. The subsequent temperature rise leads to a pressure rise within the coating, which results in a propagating ultrasound wave. US reflections from imaged structures are received with optical interferometry. With OpUS, high bandwidths (31.5 MHz) and pressures (21.5 MPa) have enabled imaging with axial resolutions better than 50 μm and at depths >20 mm. These values challenge those of conventional 40 MHz IVUS technology and show great potential for future clinical application. Recently developed nanocomposite coating materials, that are highly transmissive at light wavelengths used for PA and NIRS light, can facilitate multimodality imaging, thereby enabling molecular characterization.
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Affiliation(s)
- Callum D Little
- Department of Cardiovascular Medicine, Royal Free NHS Foundation Trust, London, United Kingdom.,Wellcome-Engineering & Physical Sciences Research Council (EPSRC) Centre for Interventional and Surgical Sciences, London, United Kingdom
| | - Richard J Colchester
- Wellcome-Engineering & Physical Sciences Research Council (EPSRC) Centre for Interventional and Surgical Sciences, London, United Kingdom.,Department of Medical Physics and Bioengineering, University College London, London, United Kingdom
| | - Sacha Noimark
- Wellcome-Engineering & Physical Sciences Research Council (EPSRC) Centre for Interventional and Surgical Sciences, London, United Kingdom.,Department of Medical Physics and Bioengineering, University College London, London, United Kingdom
| | - Gavin Manmathan
- Department of Cardiovascular Medicine, Royal Free NHS Foundation Trust, London, United Kingdom
| | - Malcolm C Finlay
- Wellcome-Engineering & Physical Sciences Research Council (EPSRC) Centre for Interventional and Surgical Sciences, London, United Kingdom.,Department of Medical Physics and Bioengineering, University College London, London, United Kingdom.,William Harvey Cardiovascular Research Institute, Queen Mary University of London and Barts Health Centre London, London, United Kingdom
| | - Adrien E Desjardins
- Wellcome-Engineering & Physical Sciences Research Council (EPSRC) Centre for Interventional and Surgical Sciences, London, United Kingdom.,Department of Medical Physics and Bioengineering, University College London, London, United Kingdom
| | - Roby D Rakhit
- Department of Cardiovascular Medicine, Royal Free NHS Foundation Trust, London, United Kingdom.,Wellcome-Engineering & Physical Sciences Research Council (EPSRC) Centre for Interventional and Surgical Sciences, London, United Kingdom
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21
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Mackle EC, Shapey J, Maneas E, Saeed SR, Bradford R, Ourselin S, Vercauteren T, Desjardins AE. Patient-Specific Polyvinyl Alcohol Phantom Fabrication with Ultrasound and X-Ray Contrast for Brain Tumor Surgery Planning. J Vis Exp 2020. [PMID: 32744524 PMCID: PMC7610642 DOI: 10.3791/61344] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Phantoms are essential tools for clinical training, surgical planning and the development of novel medical devices. However, it is challenging to create anatomically accurate head phantoms with realistic brain imaging properties because standard fabrication methods are not optimized to replicate any patient-specific anatomical detail and 3D printing materials are not optimized for imaging properties. In order to test and validate a novel navigation system for use during brain tumor surgery, an anatomically accurate phantom with realistic imaging and mechanical properties was required. Therefore, a phantom was developed using real patient data as input and 3D printing of molds to fabricate a patient-specific head phantom comprising the skull, brain and tumor with both ultrasound and X-ray contrast. The phantom also had mechanical properties that allowed the phantom tissue to be manipulated in a similar manner to how human brain tissue is handled during surgery. The phantom was successfully tested during a surgical simulation in a virtual operating room. The phantom fabrication method uses commercially available materials and is easy to reproduce. The 3D printing files can be readily shared, and the technique can be adapted to encompass many different types of tumor.
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Affiliation(s)
- Eleanor C Mackle
- Wellcome / EPSRC Centre for Interventional and Surgical Sciences, University College London; Department of Medical Physics and Biomedical Engineering, University College London;
| | - Jonathan Shapey
- Wellcome / EPSRC Centre for Interventional and Surgical Sciences, University College London; Department of Medical Physics and Biomedical Engineering, University College London; Department of Neurosurgery, National Hospital for Neurology and Neurosurgery; School of Biomedical Engineering & Imaging Sciences, King's College London
| | - Efthymios Maneas
- Wellcome / EPSRC Centre for Interventional and Surgical Sciences, University College London; Department of Medical Physics and Biomedical Engineering, University College London
| | - Shakeel R Saeed
- Department of Neurosurgery, National Hospital for Neurology and Neurosurgery; The Ear Institute, University College London; The Royal National Throat, Nose and Ear Hospital, London
| | - Robert Bradford
- Department of Neurosurgery, National Hospital for Neurology and Neurosurgery
| | - Sebastien Ourselin
- School of Biomedical Engineering & Imaging Sciences, King's College London
| | - Tom Vercauteren
- School of Biomedical Engineering & Imaging Sciences, King's College London
| | - Adrien E Desjardins
- Wellcome / EPSRC Centre for Interventional and Surgical Sciences, University College London; Department of Medical Physics and Biomedical Engineering, University College London
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22
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Maneas E, Aughwane R, Huynh N, Xia W, Ansari R, Kuniyil Ajith Singh M, Hutchinson JC, Sebire NJ, Arthurs OJ, Deprest J, Ourselin S, Beard PC, Melbourne A, Vercauteren T, David AL, Desjardins AE. Photoacoustic imaging of the human placental vasculature. J Biophotonics 2020; 13:e201900167. [PMID: 31661594 PMCID: PMC8425327 DOI: 10.1002/jbio.201900167] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 09/02/2019] [Accepted: 10/03/2019] [Indexed: 05/06/2023]
Abstract
Minimally invasive fetal interventions require accurate imaging from inside the uterine cavity. Twin-to-twin transfusion syndrome (TTTS), a condition considered in this study, occurs from abnormal vascular anastomoses in the placenta that allow blood to flow unevenly between the fetuses. Currently, TTTS is treated fetoscopically by identifying the anastomosing vessels, and then performing laser photocoagulation. However, white light fetoscopy provides limited visibility of placental vasculature, which can lead to missed anastomoses or incomplete photocoagulation. Photoacoustic (PA) imaging is an alternative imaging method that provides contrast for hemoglobin, and in this study, two PA systems were used to visualize chorionic (fetal) superficial and subsurface vasculature in human placentas. The first system comprised an optical parametric oscillator for PA excitation and a 2D Fabry-Pérot cavity ultrasound sensor; the second, light emitting diode arrays and a 1D clinical linear-array ultrasound imaging probe. Volumetric photoacoustic images were acquired from ex vivo normal term and TTTS-treated placentas. It was shown that superficial and subsurface branching blood vessels could be visualized to depths of approximately 7 mm, and that ablated tissue yielded negative image contrast. This study demonstrated the strong potential of PA imaging to guide minimally invasive fetal therapies.
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Affiliation(s)
- Efthymios Maneas
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College LondonLondonUK
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Rosalind Aughwane
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
- Institute for Women's Health, University College LondonLondonUK
| | - Nam Huynh
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College LondonLondonUK
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Wenfeng Xia
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
- School of Biomedical Engineering and Imaging Sciences, King's College LondonLondonUK
| | - Rehman Ansari
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College LondonLondonUK
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | | | - J. Ciaran Hutchinson
- NIHR Great Ormond Street Institute of Child Health Biomedical Research Centre, University College LondonLondonUK
- Department of HistopathologyGreat Ormond Street Hospital for Children NHS TrustLondonUK
| | - Neil J. Sebire
- NIHR Great Ormond Street Institute of Child Health Biomedical Research Centre, University College LondonLondonUK
- Department of HistopathologyGreat Ormond Street Hospital for Children NHS TrustLondonUK
| | - Owen J. Arthurs
- NIHR Great Ormond Street Institute of Child Health Biomedical Research Centre, University College LondonLondonUK
- Paediatric Radiology, Great Ormond Street Hospital for Children NHS TrustLondonUK
| | - Jan Deprest
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College LondonLondonUK
- Institute for Women's Health, University College LondonLondonUK
- Department of Obstetrics and GynaecologyUniversity Hospitals LeuvenLeuvenBelgium
| | - Sebastien Ourselin
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
- School of Biomedical Engineering and Imaging Sciences, King's College LondonLondonUK
| | - Paul C. Beard
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College LondonLondonUK
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Andrew Melbourne
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
- School of Biomedical Engineering and Imaging Sciences, King's College LondonLondonUK
| | - Tom Vercauteren
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
- School of Biomedical Engineering and Imaging Sciences, King's College LondonLondonUK
| | - Anna L. David
- Institute for Women's Health, University College LondonLondonUK
| | - Adrien E. Desjardins
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College LondonLondonUK
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
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23
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Alles EJ, Desjardins AE. Source Density Apodization: Image Artifact Suppression Through Source Pitch Nonuniformity. IEEE Trans Ultrason Ferroelectr Freq Control 2020; 67:497-504. [PMID: 31603778 PMCID: PMC7049469 DOI: 10.1109/tuffc.2019.2945636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Conventional ultrasound imaging probes typically comprise finite-sized arrays of periodically spaced transducer elements which, in the case of phased arrays, can result in severe grating and sidelobe artifacts. Whereas side lobes can be effectively suppressed through amplitude apodization ("AmpA"), grating lobes arising from periodicity in transducer placement can only be suppressed by decreasing the element pitch, which is technologically challenging and costly. In this work, we present source density apodization ("SDA") as an alternative apodization scheme, where the spatial source density (and, hence, the element pitch) is varied across the imaging aperture. Using an all-optical ultrasound imaging setup capable of video-rate 2-D imaging as well as dynamic and arbitrary reconfiguration of the source array geometry, we show both numerically and experimentally how SDA and AmpA are equivalent for large numbers of sources. For low numbers of sources, SDA is shown to yield superior image quality as both side and grating lobes are effectively suppressed. In addition, we demonstrate how asymmetric SDA schemes can be used to locally and dynamically improve the image quality. Finally, we demonstrate how a nonsmoothly varying spatial source density (such as that obtained for randomized arrays or in the presence of source positioning uncertainty or inaccuracy) can yield severe image artifacts. The application of SDA can, thus, yield high image quality even for low channel counts, which can ultimately result in higher imaging frame rates using acquisition systems of reduced complexity.
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24
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Ansari R, Zhang EZ, Desjardins AE, David AL, Beard PC. Use of a flexible optical fibre bundle to interrogate a Fabry-Perot sensor for photoacoustic imaging. Opt Express 2019; 27:37886-37899. [PMID: 31878562 PMCID: PMC7046039 DOI: 10.1364/oe.27.037886] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 10/31/2019] [Accepted: 11/06/2019] [Indexed: 05/07/2023]
Abstract
Photoacoustic imaging systems based on a Fabry Perot (FP) ultrasound sensor that is read-out by scanning a free-space laser beam over its surface can provide high resolution photoacoustic images. However, this type of free-space scanning usually requires a bulky 2-axis galvanometer based scanner that is not conducive to the realization of a lightweight compact imaging head. It is also unsuitable for endoscopic applications that may require complex and flexible access. To address these limitations, the use of a flexible, coherent fibre bundle to interrogate the FP sensor has been investigated. A laboratory set-up comprising an x-y scanner, a commercially available, 1.35 mm diameter, 18,000 core flexible fibre bundle with a custom-designed telecentric optical relay at its distal end was used. Measurements of the optical and acoustic performance of the FP sensor were made and compared to that obtained using a conventional free-space FP based scanner. Spatial variations in acoustic sensitivity were greater and the SNR lower with the fibre bundle implementation but high quality photoacoustic images could still be obtained. 3D images of phantoms and ex vivo tissues with a spatial resolution and fidelity consistent with a free-space scanner were acquired. By demonstrating the feasibility of interrogating the FP sensor with a flexible fibre bundle, this study advances the realization of compact hand-held clinical scanners and flexible endoscopic devices based on the FP sensing concept.
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Affiliation(s)
- Rehman Ansari
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, 43-45 Foley Street, London W1W 7TS, UK
| | - Edward Z. Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, 43-45 Foley Street, London W1W 7TS, UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, 43-45 Foley Street, London W1W 7TS, UK
| | - Anna L. David
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, 43-45 Foley Street, London W1W 7TS, UK
- Elizabeth Garrett Anderson Institute for Women’s Health, University College London, 74 Huntley Street, London WC1E 6AU, UK
| | - Paul C. Beard
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, 43-45 Foley Street, London W1W 7TS, UK
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25
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Zhao T, Desjardins AE, Ourselin S, Vercauteren T, Xia W. Minimally invasive photoacoustic imaging: Current status and future perspectives. Photoacoustics 2019; 16:100146. [PMID: 31871889 PMCID: PMC6909166 DOI: 10.1016/j.pacs.2019.100146] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 07/26/2019] [Accepted: 09/30/2019] [Indexed: 05/09/2023]
Abstract
Photoacoustic imaging (PAI) is an emerging biomedical imaging modality that is based on optical absorption contrast, capable of revealing distinct spectroscopic signatures of tissue at high spatial resolution and large imaging depths. However, clinical applications of conventional non-invasive PAI systems have been restricted to examinations of tissues at depths less than a few cm due to strong light attenuation. Minimally invasive photoacoustic imaging (miPAI) has greatly extended the landscape of PAI by delivering excitation light within tissue through miniature fibre-optic probes. In the past decade, various miPAI systems have been developed with demonstrated applicability in several clinical fields. In this article, we present an overview of the current status of miPAI and our thoughts on future perspectives.
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Affiliation(s)
- Tianrui Zhao
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing St Thomas’ Hospital London, London SE1 7EH, United Kingdom
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, United Kingdom
| | - Sebastien Ourselin
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing St Thomas’ Hospital London, London SE1 7EH, United Kingdom
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Tom Vercauteren
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing St Thomas’ Hospital London, London SE1 7EH, United Kingdom
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Wenfeng Xia
- School of Biomedical Engineering and Imaging Sciences, King’s College London, 4th Floor, Lambeth Wing St Thomas’ Hospital London, London SE1 7EH, United Kingdom
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom
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26
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Colchester RJ, Little C, Dwyer G, Noimark S, Alles EJ, Zhang EZ, Loder CD, Parkin IP, Papakonstantinou I, Beard PC, Finlay MC, Rakhit RD, Desjardins AE. All-Optical Rotational Ultrasound Imaging. Sci Rep 2019; 9:5576. [PMID: 30944379 PMCID: PMC6447544 DOI: 10.1038/s41598-019-41970-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 03/14/2019] [Indexed: 11/23/2022] Open
Abstract
Miniaturised high-resolution imaging devices are valuable for guiding minimally invasive procedures such as vascular stent placements. Here, we present all-optical rotational B-mode pulse-echo ultrasound imaging. With this device, ultrasound transmission and reception are performed with light. The all-optical transducer in the probe comprised an optical fibre that delivered pulsed excitation light to an optical head at the distal end with a multi-walled carbon nanotube and polydimethylsiloxane composite coating. This coating was photoacoustically excited to generate a highly directional ultrasound beam perpendicular to the optical fibre axis. A concave Fabry-Pérot cavity at the distal end of an optical fibre, which was interrogated with a tuneable continuous-wave laser, served as an omnidirectional ultrasound receiver. The transmitted ultrasound had a -6 dB bandwidth of 31.3 MHz and a peak-to-peak pressure of 1.87 MPa, as measured at 1.5 mm from the probe. The receiver had a noise equivalent pressure <100 Pa over a 20 MHz bandwidth. With a maximum outer probe diameter of 1.25 mm, the probe provided imaging with an axial resolution better than 50 µm, and a real-time imaging rate of 5 frames per second. To investigate the capabilities of the probe, intraluminal imaging was performed in healthy swine carotid arteries. The results demonstrate that the all-optical probe is viable for clinical rotational ultrasound imaging.
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Affiliation(s)
- Richard J Colchester
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London, WC1E 6BT, UK.
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London, W1W 7EJ, UK.
| | - Callum Little
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London, W1W 7EJ, UK
- Department of Cardiology, Royal Free Hampstead NHS Trust, Pond Street, London, NW3 2QG, UK
- Institute of Cardiovascular Science, University College London, Gower Street, London, WC1E 6BT, UK
| | - George Dwyer
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London, W1W 7EJ, UK
- Centre for Medical Image Computing, University College London, Gower Street, London, WC1E 6BT, UK
| | - Sacha Noimark
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London, W1W 7EJ, UK
- Materials Chemistry Research Centre, Department of Chemistry, University College London, London, WC1H 0AJ, UK
| | - Erwin J Alles
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London, W1W 7EJ, UK
| | - Edward Z Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London, WC1E 6BT, UK
| | - Christopher D Loder
- Department of Cardiology, Royal Free Hampstead NHS Trust, Pond Street, London, NW3 2QG, UK
- Institute of Cardiovascular Science, University College London, Gower Street, London, WC1E 6BT, UK
| | - Ivan P Parkin
- Materials Chemistry Research Centre, Department of Chemistry, University College London, London, WC1H 0AJ, UK
| | - Ioannis Papakonstantinou
- Photonic Innovations Lab, Department of Electronic and Electrical Engineering, University College London, Roberts Building, London, WC1E 7JE, UK
| | - Paul C Beard
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London, W1W 7EJ, UK
| | - Malcolm C Finlay
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London, W1W 7EJ, UK
- William Harvey Cardiovascular Research Institute, Queen Mary University of London and Barts Health Centre, London, EC1A 7BE, UK
| | - Roby D Rakhit
- Department of Cardiology, Royal Free Hampstead NHS Trust, Pond Street, London, NW3 2QG, UK
- Institute of Cardiovascular Science, University College London, Gower Street, London, WC1E 6BT, UK
| | - Adrien E Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London, WC1E 6BT, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London, W1W 7EJ, UK
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27
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Colchester RJ, Alles EJ, Desjardins AE. A directional fibre optic ultrasound transmitter based on a reduced graphene oxide and polydimethylsiloxane composite. Appl Phys Lett 2019; 114:113505. [PMID: 30967687 PMCID: PMC6428661 DOI: 10.1063/1.5089750] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 03/06/2019] [Indexed: 05/09/2023]
Abstract
Strongly directional ultrasound sources are desirable for many minimally invasive applications, as they enable high-quality imaging in the presence of positioning uncertainty. All-optical ultrasound is an emerging paradigm that exhibits high frequencies, large bandwidths, and a strong miniaturisation potential. Here, we report the design, modelling, and fabrication of a highly directional fibre-optic ultrasound transmitter that uses a composite of reduced graphene oxide and polydimethylsiloxane as the optical ultrasound generator. The ultrasound transmitter, which had an outer diameter of just 630 μm, generated ultrasound with a pressure exceeding 0.4 MPa for axial distances up to 16 mm, at a large bandwidth of 24.3 MHz. The ultrasound beam exhibited low divergence, with a beam diameter ranging between 0.6 and 2.1 mm for distances between 0 and 16 mm. The presented directional optical ultrasound source is hence well-suited to high-resolution interventional imaging.
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28
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Little CD, Poduval RK, Caulfield R, Noimark S, Colchester RJ, Loder CD, Tiwari MK, Rakhit RD, Papakonstantinou I, Desjardins AE. Micron resolution, high-fidelity three-dimensional vascular optical imaging phantoms. J Biomed Opt 2019; 24:1-4. [PMID: 30770678 PMCID: PMC6498868 DOI: 10.1117/1.jbo.24.2.020502] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/08/2019] [Indexed: 05/13/2023]
Abstract
Microscopic and mesoscale optical imaging techniques allow for three-dimensional (3-D) imaging of biological tissue across millimeter-scale regions, and imaging phantom models are invaluable for system characterization and clinical training. Phantom models that replicate complex 3-D geometries with both structural and molecular contrast, with resolution and lateral dimensions equivalent to those of imaging techniques (<20 μm), have proven elusive. We present a method for fabricating phantom models using a combination of two-photon polymerization (2PP) to print scaffolds, and microinjection of tailored tissue-mimicking materials to simulate healthy and diseased tissue. We provide a first demonstration of the capabilities of this method with intravascular optical coherence tomography, an imaging technique widely used in clinical practice. We describe the design, fabrication, and validation of three types of phantom models: a first with subresolution wires (5- to 34-μm diameter) arranged circumferentially, a second with a vessel side-branch, and a third containing a lipid inclusion within a vessel. Silicone hybrid materials and lipids, microinjected within a resin framework created with 2PP, served as tissue-mimicking materials that provided realistic optical scattering and absorption. We demonstrate that optical phantom models made with 2PP and microinjected tissue-mimicking materials can simulate complex anatomy and pathology with exquisite detail.
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Affiliation(s)
- Callum D. Little
- Wellcome Trust–EPSRC Centre for Interventional and Surgical Sciences, London, United Kingdom
- Royal Free Hospital, Department of Cardiology, London, United Kingdom
| | - Radhika K. Poduval
- University College London, Department of Electronic and Electrical Engineering, Photonic Innovations Lab, London, United Kingdom
- University College London, Department of Medical Physics and Bioengineering, London, United Kingdom
| | - Richard Caulfield
- Wellcome Trust–EPSRC Centre for Interventional and Surgical Sciences, London, United Kingdom
- University College London, Department of Medical Physics and Bioengineering, London, United Kingdom
- University College London, Nanoengineered Systems Laboratory, UCL Mechanical Engineering, London, United Kingdom
| | - Sacha Noimark
- Wellcome Trust–EPSRC Centre for Interventional and Surgical Sciences, London, United Kingdom
- University College London, Department of Medical Physics and Bioengineering, London, United Kingdom
| | - Richard J. Colchester
- Wellcome Trust–EPSRC Centre for Interventional and Surgical Sciences, London, United Kingdom
- University College London, Department of Electronic and Electrical Engineering, Photonic Innovations Lab, London, United Kingdom
| | - Chris D. Loder
- Royal Free Hospital, Department of Cardiology, London, United Kingdom
| | - Manish K. Tiwari
- Wellcome Trust–EPSRC Centre for Interventional and Surgical Sciences, London, United Kingdom
- University College London, Nanoengineered Systems Laboratory, UCL Mechanical Engineering, London, United Kingdom
| | - Roby D. Rakhit
- Royal Free Hospital, Department of Cardiology, London, United Kingdom
| | - Ioannis Papakonstantinou
- University College London, Department of Electronic and Electrical Engineering, Photonic Innovations Lab, London, United Kingdom
- Address all correspondence to Ioannis Papakonstantinou, E-mail: ; Adrien E. Desjardins, E-mail:
| | - Adrien E. Desjardins
- Wellcome Trust–EPSRC Centre for Interventional and Surgical Sciences, London, United Kingdom
- University College London, Department of Medical Physics and Bioengineering, London, United Kingdom
- Address all correspondence to Ioannis Papakonstantinou, E-mail: ; Adrien E. Desjardins, E-mail:
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29
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Mathews SJ, Little C, Loder CD, Rakhit RD, Xia W, Zhang EZ, Beard PC, Finlay MC, Desjardins AE. All-optical dual photoacoustic and optical coherence tomography intravascular probe. Photoacoustics 2018; 11:65-70. [PMID: 30112279 PMCID: PMC6092552 DOI: 10.1016/j.pacs.2018.07.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 07/16/2018] [Accepted: 07/17/2018] [Indexed: 05/09/2023]
Abstract
Intravascular imaging in percutaneous coronary interventions can be an invaluable tool in the treatment of coronary artery disease. It is of significant interest to provide molecular imaging contrast that is complementary to structural contrast provided by optical coherence tomography (OCT) and intravascular ultrasound imaging (IVUS). In this study, we developed a dual-modality intravascular imaging probe comprising a commercial OCT catheter and a high sensitivity fiber optic ultrasound sensor, to provide both photoacoustic (PA) and OCT imaging. With PA imaging, the lateral resolution varied from 18 μm to 40 μm; the axial resolution was consistently in the vicinity of 45 μm. We demonstrated the clinical potential of the probe with 2-D circumferential PA and OCT imaging, and with multispectral PA imaging.
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Affiliation(s)
- Sunish J. Mathews
- Department of Medical Physics and Biomedical Engineering, University College London, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, UK
| | - Callum Little
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, UK
- Department of Cardiology, Royal Free Hospital, London, UK
| | | | - Roby D. Rakhit
- Department of Cardiology, Royal Free Hospital, London, UK
| | - Wenfeng Xia
- Department of Medical Physics and Biomedical Engineering, University College London, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, UK
| | - Edward Z. Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, UK
| | - Paul C. Beard
- Department of Medical Physics and Biomedical Engineering, University College London, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, UK
| | - Malcolm C. Finlay
- Department of Medical Physics and Biomedical Engineering, University College London, UK
- William Harvey Cardiovascular Research Institute, Queen Mary University of London, UK
- Barts Heart Centre, London, UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, UK
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30
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Xia W, West SJ, Finlay MC, Pratt R, Mathews S, Mari JM, Ourselin S, David AL, Desjardins AE. Three-Dimensional Ultrasonic Needle Tip Tracking with a Fiber-Optic Ultrasound Receiver. J Vis Exp 2018. [PMID: 30199033 PMCID: PMC6231697 DOI: 10.3791/57207] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Ultrasound is frequently used for guiding minimally invasive procedures, but visualizing medical devices is often challenging with this imaging modality. When visualization is lost, the medical device can cause trauma to critical tissue structures. Here, a method to track the needle tip during ultrasound image-guided procedures is presented. This method involves the use of a fiber-optic ultrasound receiver that is affixed within the cannula of a medical needle to communicate ultrasonically with the external ultrasound probe. This custom probe comprises a central transducer element array and side element arrays. In addition to conventional two-dimensional (2D) B-mode ultrasound imaging provided by the central array, three-dimensional (3D) needle tip tracking is provided by the side arrays. For B-mode ultrasound imaging, a standard transmit-receive sequence with electronic beamforming is performed. For ultrasonic tracking, Golay-coded ultrasound transmissions from the 4 side arrays are received by the hydrophone sensor, and subsequently the received signals are decoded to identify the needle tip's spatial location with respect to the ultrasound imaging probe. As a preliminary validation of this method, insertions of the needle/hydrophone pair were performed in clinically realistic contexts. This novel ultrasound imaging/tracking method is compatible with current clinical workflow, and it provides reliable device tracking during in-plane and out-of-plane needle insertions.
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Affiliation(s)
- Wenfeng Xia
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London; Department of Medical Physics and Biomedical Engineering, University College London;
| | - Simeon J West
- Department of Anaesthesia, University College Hospital
| | - Malcolm C Finlay
- Department of Medical Physics and Biomedical Engineering, University College London; St Bartholomew's Hospital and Queen Mary University of London
| | - Rosalind Pratt
- Institute for Women's Health, University College London; Centre for Medical Imaging Computing, University College London
| | - Sunish Mathews
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London; Department of Medical Physics and Biomedical Engineering, University College London
| | | | - Sebastien Ourselin
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London; Department of Medical Physics and Biomedical Engineering, University College London; Centre for Medical Imaging Computing, University College London
| | - Anna L David
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London; Institute for Women's Health, University College London; Department of Development and Regeneration, KU Leuven (Katholieke Universiteit); NIHR University College London Hospitals Biomedical Research Centre
| | - Adrien E Desjardins
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London; Department of Medical Physics and Biomedical Engineering, University College London
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31
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Alles EJ, Noimark S, Maneas E, Zhang EZ, Parkin IP, Beard PC, Desjardins AE. Video-rate all-optical ultrasound imaging. Biomed Opt Express 2018; 9:3481-3494. [PMID: 30338133 PMCID: PMC6191631 DOI: 10.1364/boe.9.003481] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 06/01/2018] [Accepted: 06/06/2018] [Indexed: 05/16/2023]
Abstract
All-optical ultrasound imaging, where ultrasound is generated and detected using light, has recently been demonstrated as a viable modality that is inherently insensitive to electromagnetic interference and exhibits wide bandwidths. High-quality 2D and 3D all-optical ultrasound images of tissues have previously been presented; however, to date, long acquisition times (ranging from minutes to hours) have hindered clinical application. Here, we present the first all-optical ultrasound imaging system capable of video-rate, real-time two-dimensional imaging of biological tissue. This was achieved using a spatially extended nano-composite optical ultrasound generator, a highly sensitive fibre-optic acoustic receiver, and eccentric illumination resulting in an acoustic source exhibiting optimal directivity. This source was scanned across a one-dimensional source aperture using a fast galvo mirror, thus enabling the dynamic synthesis of source arrays comprising spatially overlapping sources at non-uniform source separation distances. The resulting system achieved a sustained frame rate of 15 Hz, a dynamic range of 30 dB, a penetration depth of at least 6 mm, a resolution of 75 µm (axial) by 100 µm (lateral), and enabled the dynamics of a pulsating ex vivo carotid artery to be captured.
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Affiliation(s)
- Erwin J. Alles
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT,
UK
- Wellcome / EPSRC Centre for Surgical and Interventional Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
| | - Sacha Noimark
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT,
UK
- Wellcome / EPSRC Centre for Surgical and Interventional Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
- Materials Chemistry Research Centre, UCL Department of Chemistry, London WC1H 0AJ, UK
| | - Efthymios Maneas
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT,
UK
- Wellcome / EPSRC Centre for Surgical and Interventional Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
| | - Edward Z. Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT,
UK
| | - Ivan P. Parkin
- Wellcome / EPSRC Centre for Surgical and Interventional Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
- Materials Chemistry Research Centre, UCL Department of Chemistry, London WC1H 0AJ, UK
| | - Paul C. Beard
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT,
UK
- Wellcome / EPSRC Centre for Surgical and Interventional Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT,
UK
- Wellcome / EPSRC Centre for Surgical and Interventional Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
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32
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Xia W, Kuniyil Ajith Singh M, Maneas E, Sato N, Shigeta Y, Agano T, Ourselin S, J West S, E Desjardins A. Handheld Real-Time LED-Based Photoacoustic and Ultrasound Imaging System for Accurate Visualization of Clinical Metal Needles and Superficial Vasculature to Guide Minimally Invasive Procedures. Sensors (Basel) 2018; 18:E1394. [PMID: 29724014 PMCID: PMC5982119 DOI: 10.3390/s18051394] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Revised: 04/25/2018] [Accepted: 04/27/2018] [Indexed: 01/11/2023]
Abstract
Ultrasound imaging is widely used to guide minimally invasive procedures, but the visualization of the invasive medical device and the procedure’s target is often challenging. Photoacoustic imaging has shown great promise for guiding minimally invasive procedures, but clinical translation of this technology has often been limited by bulky and expensive excitation sources. In this work, we demonstrate the feasibility of guiding minimally invasive procedures using a dual-mode photoacoustic and ultrasound imaging system with excitation from compact arrays of light-emitting diodes (LEDs) at 850 nm. Three validation experiments were performed. First, clinical metal needles inserted into biological tissue were imaged. Second, the imaging depth of the system was characterized using a blood-vessel-mimicking phantom. Third, the superficial vasculature in human volunteers was imaged. It was found that photoacoustic imaging enabled needle visualization with signal-to-noise ratios that were 1.2 to 2.2 times higher than those obtained with ultrasound imaging, over insertion angles of 26 to 51 degrees. With the blood vessel mimicking phantom, the maximum imaging depth was 38 mm. The superficial vasculature of a human middle finger and a human wrist were clearly visualized in real-time. We conclude that the LED-based system is promising for guiding minimally invasive procedures with peripheral tissue targets.
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Affiliation(s)
- Wenfeng Xia
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, UK.
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK.
| | - Mithun Kuniyil Ajith Singh
- Research and Business Development Division, PreXion Corporation, Stationsplein 45 A4.004, 3013AK Rotterdam, The Netherlands.
| | - Efthymios Maneas
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, UK.
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK.
| | - Naoto Sato
- Research and Development Division, 1-14-1, Kandasudacho, Chiyoda-ku, Tokyo 101-0041, Japan.
| | - Yusuke Shigeta
- Research and Development Division, 1-14-1, Kandasudacho, Chiyoda-ku, Tokyo 101-0041, Japan.
| | - Toshitaka Agano
- Research and Development Division, 1-14-1, Kandasudacho, Chiyoda-ku, Tokyo 101-0041, Japan.
| | - Sebastian Ourselin
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, UK.
- Centre for Medical Imaging Computing, University College London, Gower Street, London WC1E 6BT, UK.
| | - Simeon J West
- Department of Anaesthesia, University College Hospital, Main Theatres, Maple Bridge Link Corridor, Podium 3, 235 Euston Road, London NW1 2BU, UK.
| | - Adrien E Desjardins
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, UK.
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK.
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33
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Maneas E, Xia W, Ogunlade O, Fonseca M, Nikitichev DI, David AL, West SJ, Ourselin S, Hebden JC, Vercauteren T, Desjardins AE. Gel wax-based tissue-mimicking phantoms for multispectral photoacoustic imaging. Biomed Opt Express 2018; 9. [PMID: 29541509 PMCID: PMC5846519 DOI: 10.1364/boe.9.001151] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Tissue-mimicking phantoms are widely used for the calibration, evaluation and standardisation of medical imaging systems, and for clinical training. For photoacoustic imaging, tissue-mimicking materials (TMMs) that have tuneable optical and acoustic properties, high stability, and mechanical robustness are highly desired. In this study, gel wax is introduced as a TMM that satisfies these criteria for developing photoacoustic imaging phantoms. The reduced scattering and optical absorption coefficients were independently tuned with the addition of TiO2 and oil-based inks. The frequency-dependent acoustic attenuation obeyed a power law; for native gel wax, it varied from 0.71 dB/cm at 3 MHz to 9.93 dB/cm at 12 MHz. The chosen oil-based inks, which have different optical absorption spectra in the range of 400 to 900 nm, were found to have good photostability under pulsed illumination with photoacoustic excitation light. Optically heterogeneous phantoms that comprised of inclusions with different concentrations of carbon black and coloured inks were fabricated, and multispectral photoacoustic imaging was performed with an optical parametric oscillator and a planar Fabry-Pérot sensor. We conclude that gel wax is well suited as a TMM for multispectral photoacoustic imaging.
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Affiliation(s)
- Efthymios Maneas
- Wellcome / EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT,
UK
| | - Wenfeng Xia
- Wellcome / EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT,
UK
| | - Olumide Ogunlade
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT,
UK
| | - Martina Fonseca
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT,
UK
| | - Daniil I. Nikitichev
- Wellcome / EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT,
UK
- Translational Imaging Group, Centre for Medical Image Computing, Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT,
UK
| | - Anna L. David
- Wellcome / EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
- Institute for Women’s Health, University College London, 86-96 Chenies Mews, London WC1E 6HX,
UK
- Department of Development and Regeneration, KU Leuven (Katholieke Universiteit),
Belgium
| | - Simeon J. West
- Department of Anaesthesia, University College Hospital, Main Theatres, Maple Bridge Link Corridor, Podium 3, 235 Euston Road, London NW1 2BU,
UK
| | - Sebastien Ourselin
- Wellcome / EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT,
UK
- Translational Imaging Group, Centre for Medical Image Computing, Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT,
UK
| | - Jeremy C. Hebden
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT,
UK
| | - Tom Vercauteren
- Wellcome / EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT,
UK
- Translational Imaging Group, Centre for Medical Image Computing, Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT,
UK
| | - Adrien E. Desjardins
- Wellcome / EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT,
UK
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34
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Maneas E, Xia W, Nikitichev DI, Daher B, Manimaran M, Wong RYJ, Chang CW, Rahmani B, Capelli C, Schievano S, Burriesci G, Ourselin S, David AL, Finlay MC, West SJ, Vercauteren T, Desjardins AE. Anatomically realistic ultrasound phantoms using gel wax with 3D printed moulds. Phys Med Biol 2018; 63:015033. [PMID: 29186007 PMCID: PMC5802334 DOI: 10.1088/1361-6560/aa9e2c] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Here we describe methods for creating tissue-mimicking ultrasound phantoms based on patient anatomy using a soft material called gel wax. To recreate acoustically realistic tissue properties, two additives to gel wax were considered: paraffin wax to increase acoustic attenuation, and solid glass spheres to increase backscattering. The frequency dependence of ultrasound attenuation was well described with a power law over the measured range of 3–10 MHz. With the addition of paraffin wax in concentrations of 0 to 8 w/w%, attenuation varied from 0.72 to 2.91 dB cm−1 at 3 MHz and from 6.84 to 26.63 dB cm−1 at 10 MHz. With solid glass sphere concentrations in the range of 0.025–0.9 w/w%, acoustic backscattering consistent with a wide range of ultrasonic appearances was achieved. Native gel wax maintained its integrity during compressive deformations up to 60%; its Young’s modulus was 17.4 ± 1.4 kPa. The gel wax with additives was shaped by melting and pouring it into 3D printed moulds. Three different phantoms were constructed: a nerve and vessel phantom for peripheral nerve blocks, a heart atrium phantom, and a placental phantom for minimally-invasive fetal interventions. In the first, nerves and vessels were represented as hyperechoic and hypoechoic tubular structures, respectively, in a homogeneous background. The second phantom comprised atria derived from an MRI scan of a patient with an intervening septum and adjoining vena cavae. The third comprised the chorionic surface of a placenta with superficial fetal vessels derived from an image of a post-partum human placenta. Gel wax is a material with widely tuneable ultrasound properties and mechanical characteristics that are well suited for creating patient-specific ultrasound phantoms in several clinical disciplines.
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Affiliation(s)
- Efthymios Maneas
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom. Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, United Kingdom. These authors contributed equally to this work
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35
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Ansari R, Zhang EZ, Desjardins AE, Beard PC. All-optical forward-viewing photoacoustic probe for high-resolution 3D endoscopy. Light Sci Appl 2018; 7:75. [PMID: 30323927 PMCID: PMC6177463 DOI: 10.1038/s41377-018-0070-5] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 08/29/2018] [Accepted: 08/30/2018] [Indexed: 05/03/2023]
Abstract
A miniature forward-viewing endoscopic probe that provides high-resolution 3D photoacoustic images is demonstrated. The probe is of outer diameter 3.2 mm and comprised of a transparent Fabry-Pérot (FP) polymer-film ultrasound sensor that is located at the distal end of a rigid optical fiber bundle. Excitation laser pulses are coupled simultaneously into all cores of the bundle and are transmitted through the FP sensor to provide wide-field tissue illumination at the distal end. The resulting photoacoustic waves are mapped in 2D by sequentially scanning the input end of the bundle with an interrogation laser beam in order to individually address different points on the FP sensor. In this way, the sensor acts as a high-density ultrasound array that is comprised of 50,000 individual elements, each of which is 12 µm in diameter, within the 3.2 mm diameter footprint of the probe. The fine spatial sampling that this affords, along with the wide bandwidth (f -3dB = 34 MHz) of the sensor, enables a high-resolution photoacoustic image to be reconstructed. The measured on-axis lateral resolution of the probe was depth-dependent and ranged from 45-170 µm for depths between 1 and 7 mm, and the vertical resolution was 31 µm over the same depth range. The system was evaluated by acquiring 3D images of absorbing phantoms and the microvascular anatomies of a duck embryo and mouse skin. Excellent image fidelity was demonstrated. It is anticipated that this type of probe could find application as a tool for guiding laparoscopic procedures, fetal surgery and other minimally invasive interventions that require a millimeter-scale forward-viewing 3D photoacoustic imaging probe.
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Affiliation(s)
- Rehman Ansari
- Department Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London, W1W 7EJ UK
| | - Edward Z. Zhang
- Department Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London, W1W 7EJ UK
| | - Adrien E. Desjardins
- Department Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London, W1W 7EJ UK
| | - Paul C. Beard
- Department Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London, W1W 7EJ UK
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Finlay MC, Mosse CA, Colchester RJ, Noimark S, Zhang EZ, Ourselin S, Beard PC, Schilling RJ, Parkin IP, Papakonstantinou I, Desjardins AE. Through-needle all-optical ultrasound imaging in vivo: a preclinical swine study. Light Sci Appl 2017; 6:e17103. [PMID: 30167220 PMCID: PMC6062020 DOI: 10.1038/lsa.2017.103] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 06/11/2017] [Accepted: 06/14/2017] [Indexed: 05/08/2023]
Abstract
High-frequency ultrasound imaging can provide exquisite visualizations of tissue to guide minimally invasive procedures. Here, we demonstrate that an all-optical ultrasound transducer, through which light guided by optical fibers is used to generate and receive ultrasound, is suitable for real-time invasive medical imaging in vivo. Broad-bandwidth ultrasound generation was achieved through the photoacoustic excitation of a multiwalled carbon nanotube-polydimethylsiloxane composite coating on the distal end of a 300-μm multi-mode optical fiber by a pulsed laser. The interrogation of a high-finesse Fabry-Pérot cavity on a single-mode optical fiber by a wavelength-tunable continuous-wave laser was applied for ultrasound reception. This transducer was integrated within a custom inner transseptal needle (diameter 1.08 mm; length 78 cm) that included a metallic septum to acoustically isolate the two optical fibers. The use of this needle within the beating heart of a pig provided unprecedented real-time views (50 Hz scan rate) of cardiac tissue (depth: 2.5 cm; axial resolution: 64 μm) and revealed the critical anatomical structures required to safely perform a transseptal crossing: the right and left atrial walls, the right atrial appendage, and the limbus fossae ovalis. This new paradigm will allow ultrasound imaging to be integrated into a broad range of minimally invasive devices in different clinical contexts.
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Affiliation(s)
- Malcolm C Finlay
- William Harvey Cardiovascular Research Institute, Queen Mary University of London and Barts Heart Centre, London EC1A 7BE, UK
| | - Charles A Mosse
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, UK
| | - Richard J Colchester
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, UK
| | - Sacha Noimark
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, UK
- UCL Centre for Materials Research, Department of Chemistry, University College London, London WC1H 0AJ, UK
| | - Edward Z Zhang
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, UK
| | - Sebastien Ourselin
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, UK
| | - Paul C Beard
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, UK
| | - Richard J Schilling
- William Harvey Cardiovascular Research Institute, Queen Mary University of London and Barts Heart Centre, London EC1A 7BE, UK
| | - Ivan P Parkin
- UCL Centre for Materials Research, Department of Chemistry, University College London, London WC1H 0AJ, UK
| | - Ioannis Papakonstantinou
- Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, UK
| | - Adrien E Desjardins
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, UK
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37
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Xia W, Noimark S, Ourselin S, West SJ, Finlay MC, David AL, Desjardins AE. Ultrasonic Needle Tracking with a Fibre-Optic Ultrasound Transmitter for Guidance of Minimally Invasive Fetal Surgery. Med Image Comput Comput Assist Interv 2017; 10434:637-645. [PMID: 28948240 DOI: 10.1007/978-3-319-66185-8_72] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ultrasound imaging is widely used for guiding minimally invasive procedures, including fetal surgery. Visualisation of medical devices such as medical needles is critically important and it remains challenging in many clinical contexts. During in-plane insertions, a needle can have poor visibility at steep insertion angles and at large insertion depths. During out-of-plane insertions, the needle tip can have a similar ultrasonic appearance to the needle shaft when it intersects with the ultrasound imaging plane. When the needle tip is not accurately identified, it can damage critical structures, with potentially severe consequences, including loss of pregnancy. In this paper, we present a tracking system to directly visualise the needle tip with an ultrasonic beacon. The waves transmitted by the beacon were received by an external ultrasound imaging probe. Pairs of co-registered images were acquired in rapid succession with this probe: a photoacoustic image obtained with the system in receive-only mode, and a conventional B-mode ultrasound image. The beacon comprised a custom elastomeric nanocomposite coating at the distal end of an optical fibre, which was positioned within the lumen of a commercial 22 gauge needle. Delivery of pulsed light to the coating resulted in the photoacoustic generation of ultrasonic waves. The measured tracking accuracies in water in the axial and lateral dimensions were 0.39±0.19 mm and 1.85±0.29 mm, respectively. To obtain a preliminary indication of the clinical potential of this ultrasonic needle tracking system, needle insertions were performed in an in vivo fetal sheep model. The results demonstrate that ultrasonic needle tracking with a fibre-optic transmitter is feasible in a clinically realistic fetal surgery environment, and that it could be useful to guide minimally invasive procedures by providing accurate visualisation of the medical device tip.
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Affiliation(s)
- Wenfeng Xia
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK
| | - Sacha Noimark
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK.,Materials Chemistry Research Centre, Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK
| | - Sebastien Ourselin
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK
| | - Simeon J West
- Department of Anaesthesia, University College Hospital, 235 Euston Road, London NW1 2BU, UK
| | - Malcolm C Finlay
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK.,St Bartholomew's Hospital and Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Anna L David
- Institute for Women's Health, University College London, 86-96 Chenies Mews, London WC1E 6HX, UK
| | - Adrien E Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK
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38
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Poduval RK, Noimark S, Colchester RJ, Macdonald TJ, Parkin IP, Desjardins AE, Papakonstantinou I. Optical fiber ultrasound transmitter with electrospun carbon nanotube-polymer composite. Appl Phys Lett 2017; 110:223701. [PMID: 28652642 PMCID: PMC5453807 DOI: 10.1063/1.4984838] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 05/18/2017] [Indexed: 05/20/2023]
Abstract
All-optical ultrasound transducers are promising for imaging applications in minimally invasive surgery. In these devices, ultrasound is transmitted and received through laser modulation, and they can be readily miniaturized using optical fibers for light delivery. Here, we report optical ultrasound transmitters fabricated by electrospinning an absorbing polymer composite directly onto the end-face of optical fibers. The composite coating consisting of an aqueous dispersion of multi-walled carbon nanotubes (MWCNTs) in polyvinyl alcohol was directly electrospun onto the cleaved surface of a multimode optical fiber and subsequently dip-coated with polydimethylsiloxane (PDMS). This formed a uniform nanofibrous absorbing mesh over the optical fiber end-face wherein the constituent MWCNTs were aligned preferentially along individual nanofibers. Infiltration of the PDMS through this nanofibrous mesh onto the underlying substrate was observed and the resulting composites exhibited high optical absorption (>97%). Thickness control from 2.3 μm to 41.4 μm was obtained by varying the electrospinning time. Under laser excitation with 11 μJ pulse energy, ultrasound pressures of 1.59 MPa were achieved at 1.5 mm from the coatings. On comparing the electrospun ultrasound transmitters with a dip-coated reference fabricated using the same constituent materials and possessing identical optical absorption, a five-fold increase in the generated pressure and wider bandwidth was observed. The electrospun transmitters exhibited high optical absorption, good elastomer infiltration, and ultrasound generation capability in the range of pressures used for clinical pulse-echo imaging. All-optical ultrasound probes with such transmitters fabricated by electrospinning could be well-suited for incorporation into catheters and needles for diagnostics and therapeutic applications.
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Affiliation(s)
- Radhika K Poduval
- Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, United Kingdom
| | | | - Richard J Colchester
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - Thomas J Macdonald
- Materials Chemistry Centre, Department of Chemistry, University College London, London WC1H 0AJ, United Kingdom
| | - Ivan P Parkin
- Materials Chemistry Centre, Department of Chemistry, University College London, London WC1H 0AJ, United Kingdom
| | - Adrien E Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - Ioannis Papakonstantinou
- Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, United Kingdom
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Alles EJ, Fook Sheung N, Noimark S, Zhang EZ, Beard PC, Desjardins AE. A reconfigurable all-optical ultrasound transducer array for 3D endoscopic imaging. Sci Rep 2017; 7:1208. [PMID: 28446784 PMCID: PMC5430692 DOI: 10.1038/s41598-017-01375-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 03/29/2017] [Indexed: 11/13/2022] Open
Abstract
A miniature all-optical ultrasound imaging system is presented that generates three-dimensional images using a stationary, real acoustic source aperture. Discrete acoustic sources were sequentially addressed by scanning a focussed optical beam across the proximal end of a coherent fibre bundle; high-frequency ultrasound (156% fractional bandwidth centred around 13.5 MHz) was generated photoacoustically in the corresponding regions of an optically absorbing coating deposited at the distal end. Paired with a single fibre-optic ultrasound detector, the imaging probe (3.5 mm outer diameter) achieved high on-axis resolutions of 97 μm, 179 μm and 110 μm in the x, y and z directions, respectively. Furthermore, the optical scan pattern, and thus the acoustic source array geometry, was readily reconfigured. Implementing four different array geometries revealed a strong dependency of the image quality on the source location pattern. Thus, by employing optical technology, a miniature ultrasound probe was fabricated that allows for arbitrary source array geometries, which is suitable for three-dimensional endoscopic and laparoscopic imaging, as was demonstrated on ex vivo porcine cardiac tissue.
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Affiliation(s)
- Erwin J Alles
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK.
| | - Nora Fook Sheung
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
| | - Sacha Noimark
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
- Materials Chemistry Research Centre, UCL Department of Chemistry, London, WC1H 0AJ, UK
| | - Edward Z Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
| | - Paul C Beard
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
| | - Adrien E Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
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40
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Schneider C, Johnson SP, Gurusamy K, Cook RJ, Desjardins AE, Hawkes DJ, Davidson BR, Walker-Samuel S. Identification of liver metastases with probe-based confocal laser endomicroscopy at two excitation wavelengths. Lasers Surg Med 2017; 49:280-292. [PMID: 27990658 PMCID: PMC5396307 DOI: 10.1002/lsm.22617] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/20/2016] [Indexed: 12/16/2022]
Abstract
BACKGROUND Metastasis of colorectal cancer to the liver is the most common indication for hepatic resection in a western population. Incomplete excision of malignancy due to residual microscopic disease normally results in worse patient outcome. Therefore, a method aiding in the real time discrimination of normal and malignant tissue on a microscopic level would be of benefit. MATERIAL AND METHODS The ability of fluorescent probe-based confocal laser endomicroscopy (pCLE) to identify normal and malignant liver tissue was evaluated in an orthotopic murine model of colorectal cancer liver metastasis (CRLM). To maximise information yield, two clinical fluorophores, fluorescein and indocyanine green (ICG) were injected and imaged in a dual wavelength approach (488 and 660 nm, respectively). Visual tissue characteristics on pCLE examination were compared with histological features. Fluorescence intensity in both tissues was statistically analysed to elucidate if this can be used to differentiate between normal and malignant tissue. RESULTS Fluorescein (488 nm) enabled good visualisation of normal and CRLM tissue, whereas ICG (660 nm) visualisation was limited to normal liver tissue only. Fluorescence intensity in areas of CRLM was typically 53-100% lower than normal hepatic parenchyma. Using general linear mixed modelling and receiver operating characteristic analysis, high fluorescence intensity was found to be statistically more likely in normal hepatic tissue. CONCLUSION Real time discrimination between normal liver parenchyma and metastatic tissue with pCLE examination of fluorescein and ICG is feasible. Employing two (rather than a single) fluorophores allows a combination of qualitative and quantitative characteristics to be used to distinguish between hepatic parenchyma and CRLM. Lasers Surg. Med. 49:280-292, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Crispin Schneider
- Division of Surgery & Interventional Science, University College London, Floor 9, Royal Free Hospital, London, NW3 2QG, UK
| | - Sean P Johnson
- UCL Centre for Advanced Biomedical Imaging, Paul O'Gorman Building, University College London, 72 Huntley Street, London, WC1E 6DD, UK
| | - Kurinchi Gurusamy
- Division of Surgery & Interventional Science, University College London, Floor 9, Royal Free Hospital, London, NW3 2QG, UK
| | - Richard J Cook
- Department of Tissue Engineering and Biophotonics, King's College London, Dental Institute-Central Office, Floor 18, Guy's Tower, Guy's Hospital, London, SE1 9RT, UK
| | - Adrien E Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, Gower Street, London, WC1E 6BT, UK
| | - David J Hawkes
- Centre for Medical Image Computing, University College London, The Front Engineering Building, Floor 3, Malet Place, London, WC1E 7JE, UK
| | - Brian R Davidson
- Division of Surgery & Interventional Science, University College London, Floor 9, Royal Free Hospital, London, NW3 2QG, UK
| | - Simon Walker-Samuel
- UCL Centre for Advanced Biomedical Imaging, Paul O'Gorman Building, University College London, 72 Huntley Street, London, WC1E 6DD, UK
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Hill ER, Xia W, Clarkson MJ, Desjardins AE. Identification and removal of laser-induced noise in photoacoustic imaging using singular value decomposition. Biomed Opt Express 2017; 8:68-77. [PMID: 28101402 PMCID: PMC5231316 DOI: 10.1364/boe.8.000068] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/28/2016] [Accepted: 11/11/2016] [Indexed: 05/20/2023]
Abstract
Singular value decomposition (SVD) was used to identify and remove laser-induced noise in photoacoustic images acquired with a clinical ultrasound scanner. This noise, which was prominent in the radiofrequency data acquired in parallel from multiple transducer elements, was induced by the excitation light source. It was modelled by truncating the SVD matrices so that only the first few largest singular value components were retained, and subtracted prior to image reconstruction. The dependency of the signal amplitude and the number of the largest singular value components used for noise modeling was investigated for different photoacoustic source geometries. Validation was performed with simulated data and measured noise, and with photoacoustic images acquired from the human forearm and finger in vivo using L14-5/38 and L40-8/12 linear array clinical imaging probes. The use of only one singular value component was found to be sufficient to achieve near-complete removal of laser-induced noise from reconstructed images. This method has strong potential to increase image quality for a wide range of photoacoustic imaging systems with parallel data acquisition.
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Affiliation(s)
- Emma R. Hill
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
- Equal contribution
| | - Wenfeng Xia
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
- Equal contribution
| | - Matthew J. Clarkson
- Translational Imaging Group (TIG), Centre for Medical Image Computing (CMIC), Dept. of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
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Alles EJ, Noimark S, Zhang E, Beard PC, Desjardins AE. Pencil beam all-optical ultrasound imaging. Biomed Opt Express 2016; 7:3696-3704. [PMID: 27699130 PMCID: PMC5030042 DOI: 10.1364/boe.7.003696] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 08/08/2016] [Accepted: 08/08/2016] [Indexed: 05/18/2023]
Abstract
A miniature, directional fibre-optic acoustic source is presented that employs geometrical focussing to generate a nearly-collimated acoustic pencil beam. When paired with a fibre-optic acoustic detector, an all-optical ultrasound probe with an outer diameter of 2.5 mm is obtained that acquires a pulse-echo image line at each probe position without the need for image reconstruction. B-mode images can be acquired by translating the probe and concatenating the image lines, and artefacts resulting from probe positioning uncertainty are shown to be significantly lower than those observed for conventional synthetic aperture scanning of a non-directional acoustic source. The high image quality obtained for excised vascular tissue suggests that the all-optical ultrasound probe is ideally suited for in vivo, interventional applications.
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Affiliation(s)
- Erwin J. Alles
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
| | - Sacha Noimark
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
- Materials Chemistry Research Centre, UCL Department of Chemistry, London WC1H 0AJ, UK
| | - Edward Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
| | - Paul C. Beard
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
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43
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Xia W, Mari JM, West SJ, Ginsberg Y, David AL, Ourselin S, Desjardins AE. In-plane ultrasonic needle tracking using a fiber-optic hydrophone. Med Phys 2016; 42:5983-91. [PMID: 26429273 DOI: 10.1118/1.4931418] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
PURPOSE Accurate and efficient guidance of needles to procedural targets is critically important during percutaneous interventional procedures. Ultrasound imaging is widely used for real-time image guidance in a variety of clinical contexts, but with this modality, uncertainties about the location of the needle tip within the image plane lead to significant complications. Whilst several methods have been proposed to improve the visibility of the needle, achieving accuracy and compatibility with current clinical practice is an ongoing challenge. In this paper, the authors present a method for directly visualizing the needle tip using an integrated fiber-optic ultrasound receiver in conjunction with the imaging probe used to acquire B-mode ultrasound images. METHODS Needle visualization and ultrasound imaging were performed with a clinical ultrasound imaging system. A miniature fiber-optic ultrasound hydrophone was integrated into a 20 gauge injection needle tip to receive transmissions from individual transducer elements of the ultrasound imaging probe. The received signals were reconstructed to create an image of the needle tip. Ultrasound B-mode imaging was interleaved with needle tip imaging. A first set of measurements was acquired in water and tissue ex vivo with a wide range of insertion angles (15°-68°) to study the accuracy and sensitivity of the tracking method. A second set was acquired in an in vivo swine model, with needle insertions to the brachial plexus. A third set was acquired in an in vivo ovine model for fetal interventions, with insertions to different locations within the uterine cavity. Two linear ultrasound imaging probes were used: a 14-5 MHz probe for the first and second sets, and a 9-4 MHz probe for the third. RESULTS During insertions in tissue ex vivo and in vivo, the imaged needle tip had submillimeter axial and lateral dimensions. The signal-to-noise (SNR) of the needle tip was found to depend on the insertion angle. With the needle tip in water, the SNR of the needle tip varied with insertion angle, attaining values of 284 at 27° and 501 at 68°. In swine tissue ex vivo, the SNR decreased from 80 at 15° to 16 at 61°. In swine tissue in vivo, the SNR varied with depth, from 200 at 17.5 mm to 48 at 26 mm, with a constant insertion angle of 40°. In ovine tissue in vivo, within the uterine cavity, the SNR varied from 46.4 at 25 mm depth to 18.4 at 32 mm depth, with insertion angles in the range of 26°-65°. CONCLUSIONS A fiber-optic ultrasound receiver integrated into the needle cannula in combination with single-element transmissions from the imaging probe allows for direct visualization of the needle tip within the ultrasound imaging plane. Visualization of the needle tip was achieved at depths and insertion angles that are encountered during nerve blocks and fetal interventions. The method presented in this paper has strong potential to improve the safety and efficiency of ultrasound-guided needle insertions.
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Affiliation(s)
- Wenfeng Xia
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Jean Martial Mari
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom and GePaSud, University of French Polynesia, Faa'a 98702, French Polynesia
| | - Simeon J West
- Department of Anaesthesia, University College Hospital, Main Theatres, Maple Bridge Link Corridor, Podium 3, 235 Euston Road, London NW1 2BU, United Kingdom
| | - Yuval Ginsberg
- Institute for Women's Health, University College London, 86-96 Chenies Mews, London WC1E 6HX, United Kingdom
| | - Anna L David
- Institute for Women's Health, University College London, 86-96 Chenies Mews, London WC1E 6HX, United Kingdom
| | - Sebastien Ourselin
- Center for Medical Imaging Computing, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Adrien E Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom
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Xia W, Ginsberg Y, West SJ, Nikitichev DI, Ourselin S, David AL, Desjardins AE. Coded excitation ultrasonic needle tracking: An in vivo study. Med Phys 2016; 43:4065. [PMID: 27370125 PMCID: PMC5207306 DOI: 10.1118/1.4953205] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 04/25/2016] [Accepted: 05/21/2016] [Indexed: 01/22/2023] Open
Abstract
PURPOSE Accurate and efficient guidance of medical devices to procedural targets lies at the heart of interventional procedures. Ultrasound imaging is commonly used for device guidance, but determining the location of the device tip can be challenging. Various methods have been proposed to track medical devices during ultrasound-guided procedures, but widespread clinical adoption has remained elusive. With ultrasonic tracking, the location of a medical device is determined by ultrasonic communication between the ultrasound imaging probe and a transducer integrated into the medical device. The signal-to-noise ratio (SNR) of the transducer data is an important determinant of the depth in tissue at which tracking can be performed. In this paper, the authors present a new generation of ultrasonic tracking in which coded excitation is used to improve the SNR without spatial averaging. METHODS A fiber optic hydrophone was integrated into the cannula of a 20 gauge insertion needle. This transducer received transmissions from the ultrasound imaging probe, and the data were processed to obtain a tracking image of the needle tip. Excitation using Barker or Golay codes was performed to improve the SNR, and conventional bipolar excitation was performed for comparison. The performance of the coded excitation ultrasonic tracking system was evaluated in an in vivo ovine model with insertions to the brachial plexus and the uterine cavity. RESULTS Coded excitation significantly increased the SNRs of the tracking images, as compared with bipolar excitation. During an insertion to the brachial plexus, the SNR was increased by factors of 3.5 for Barker coding and 7.1 for Golay coding. During insertions into the uterine cavity, these factors ranged from 2.9 to 4.2 for Barker coding and 5.4 to 8.5 for Golay coding. The maximum SNR was 670, which was obtained with Golay coding during needle withdrawal from the brachial plexus. Range sidelobe artifacts were observed in tracking images obtained with Barker coded excitation, and they were visually absent with Golay coded excitation. The spatial tracking accuracy was unaffected by coded excitation. CONCLUSIONS Coded excitation is a viable method for improving the SNR in ultrasonic tracking without compromising spatial accuracy. This method provided SNR increases that are consistent with theoretical expectations, even in the presence of physiological motion. With the ultrasonic tracking system in this study, the SNR increases will have direct clinical implications in a broad range of interventional procedures by improving visibility of medical devices at large depths.
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Affiliation(s)
- Wenfeng Xia
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Yuval Ginsberg
- Institute for Women’s Health, University College London, 86-96 Chenies Mews, London WC1E 6HX, United Kingdom
| | - Simeon J. West
- Department of Anaesthesia, University College Hospital, Main Theaters, Maple Bridge Link Corridor, Podium 3, 235 Euston Road, London NW1 2BU, United Kingdom
| | - Daniil I. Nikitichev
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Sebastien Ourselin
- Center for Medical Imaging Computing, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Anna L. David
- Institute for Women’s Health, University College London, 86-96 Chenies Mews, London WC1E 6HX, United Kingdom
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom
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45
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Tunnell JW, Desjardins AE, Galindo L, Georgakoudi I, McGee SA, Mirkovic J, Mueller MG, Nazemi J, Nguyen FT, Wax A, Zhang Q, Dasari RR, Feld MS. Instrumentation for Multi-modal Spectroscopic Diagnosis of Epithelial Dysplasia. Technol Cancer Res Treat 2016; 2:505-14. [PMID: 14640762 DOI: 10.1177/153303460300200603] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Reflectance and fluorescence spectroscopies have shown great promise for early detection of epithelial dysplasia. We have developed a clinical reflectance spectrofluorimeter for multimodal spectroscopic diagnosis of epithelial dysplasia. This clinical instrument, the FastEEM, collects white light reflectance and fluorescence excitation-emission matrices (EEM's) within a fraction of a second. In this paper we describe the FastEEM instrumentation, designed for collection of multi-modal spectroscopic data. We illustrate its performance using tissue phantoms with well defined optical properties and biochemicals of known fluorescence properties. In addition, we discuss our plans to develop a system that combines a multi-spectral imaging device for wide area surveillance with this contact probe device.
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Affiliation(s)
- J W Tunnell
- G.R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology, 77 Massachusetts Ave., Bldg 6-014, Cambridge, MA 02139, USA
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46
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Nikitichev DI, Xia W, Hill E, Mosse CA, Perkins T, Konyn K, Ourselin S, Desjardins AE, Vercauteren T. Music-of-light stethoscope: a demonstration of the photoacoustic effect. ACTA ACUST UNITED AC 2016; 51:045015. [PMID: 29249838 PMCID: PMC5717520 DOI: 10.1088/0031-9120/51/4/045015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 04/11/2016] [Accepted: 04/25/2016] [Indexed: 11/17/2022]
Abstract
In this paper we present a system aimed at demonstrating the photoacoustic (PA) effect for educational purposes. PA imaging is a hybrid imaging modality that requires no contrast agent and has a great potential for spine and brain lesion characterisation, breast cancer and blood flow monitoring notably in the context of fetal surgery. It relies on combining light excitation with ultrasound reception. Our brief was to present and explain PA imaging in a public-friendly way suitable for a variety of ages and backgrounds. We developed a simple, accessible demonstration unit using readily available materials. We used a modulated light emitting diode (LED) torch and an electronic stethoscope. The output of a music player was used for light modulation and the chest piece of the stethoscope covered by a black tape was used as an absorbing target and an enclosed chamber. This demonstration unit was presented to the public at the Bloomsbury Festival On Light in October 2015. Our stall was visited by over 100 people of varying ages. Twenty families returned in-depth evaluation questionnaires, which show that our explanations of the photoacoustic effect were well understood. Their interest in biomedical engineering was increased.
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Affiliation(s)
- D I Nikitichev
- Translational Imaging group, Centre for Medical Image Computing, University College London, London, UK.,Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT, London, UK.,
| | - W Xia
- Translational Imaging group, Centre for Medical Image Computing, University College London, London, UK
| | - E Hill
- Translational Imaging group, Centre for Medical Image Computing, University College London, London, UK
| | - C A Mosse
- Translational Imaging group, Centre for Medical Image Computing, University College London, London, UK
| | - T Perkins
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT, London, UK
| | - K Konyn
- Translational Imaging group, Centre for Medical Image Computing, University College London, London, UK.,Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT, London, UK
| | - S Ourselin
- Translational Imaging group, Centre for Medical Image Computing, University College London, London, UK.,Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT, London, UK
| | - A E Desjardins
- Translational Imaging group, Centre for Medical Image Computing, University College London, London, UK
| | - T Vercauteren
- Translational Imaging group, Centre for Medical Image Computing, University College London, London, UK.,Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT, London, UK
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47
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Nikitichev DI, Barburas A, McPherson K, Mari JM, West SJ, Desjardins AE. Construction of 3-Dimensional Printed Ultrasound Phantoms With Wall-less Vessels. J Ultrasound Med 2016; 35:1333-9. [PMID: 27162278 DOI: 10.7863/ultra.15.06012] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 09/15/2015] [Indexed: 05/08/2023]
Abstract
Ultrasound phantoms are invaluable as training tools for vascular access procedures. We developed ultrasound phantoms with wall-less vessels using 3-dimensional printed chambers. Agar was used as a soft tissue-mimicking material, and the wall-less vessels were created with rods that were retracted after the agar was set. The chambers had integrated luer connectors to allow for fluid injections with clinical syringes. Several variations on this design are presented, which include branched and stenotic vessels. The results show that 3-dimensional printing can be well suited to the construction of wall-less ultrasound phantoms, with designs that can be readily customized and shared electronically.
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Affiliation(s)
- Daniil I Nikitichev
- Department of Medical Physics and Biomedical Engineering, University College London, London, England
| | - Anamaria Barburas
- Department of Medical Physics and Biomedical Engineering, University College London, London, England
| | | | - Jean-Martial Mari
- Department of Medical Physics and Biomedical Engineering, University College London, London, EnglandUniversity of French Polynesia, Tahiti, French Polynesia
| | | | - Adrien E Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, London, England
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48
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Alles EJ, Colchester RJ, Desjardins AE. Adaptive Light Modulation for Improved Resolution and Efficiency in All-Optical Pulse-Echo Ultrasound. IEEE Trans Ultrason Ferroelectr Freq Control 2016; 63:83-90. [PMID: 26552084 DOI: 10.1109/tuffc.2015.2497465] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In biomedical all-optical pulse-echo ultrasound systems, ultrasound is generated with the photoacoustic effect by illuminating an optically absorbing structure with a temporally modulated light source. Nanosecond range laser pulses are typically used, which can yield bandwidths exceeding 100 MHz. However, acoustical attenuation within tissue or nonuniformities in the detector or source power spectra result in energy loss at the affected frequencies and in a reduced overall system efficiency. In this work, a laser diode is used to generate linear and nonlinear chirp optical modulations that are extended to microsecond time scales, with bandwidths constrained to the system sensitivity. Compared to those obtained using a 2-ns pulsed laser, pulse-echo images of a phantom obtained using linear chirp excitation exhibit similar axial resolution (99 versus 92 μm, respectively) and signal-to-noise ratios (SNRs) (10.3 versus 9.6 dB). In addition, the axial point spread function (PSF) exhibits lower sidelobe levels in the case of chirp modulation. Using nonlinear (time-stretched) chirp excitations, where the nonlinearity is computed from measurements of the spectral sensitivity of the system, the power spectrum of the imaging system was flattened and its bandwidth broadened. Consequently, the PSF has a narrower axial extent and still lower sidelobe levels. Pulse-echo images acquired with time-stretched chirps as optical modulation have higher axial resolution (64 μm) than those obtained with linear chirps, at the expense of a lower SNR (6.8 dB). Using a linear or time-stretched chirp, the conversion efficiency from optical power to acoustical pressure improved by a factor of 70 or 61, respectively, compared to that obtained with pulsed excitation.
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49
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Schneider C, Johnson SP, Walker-Samuel S, Gurusamy K, Clarkson MJ, Thompson S, Song Y, Totz J, Cook RJ, Desjardins AE, Hawkes DJ, Davidson BR. Utilizing confocal laser endomicroscopy for evaluating the adequacy of laparoscopic liver ablation. Lasers Surg Med 2015; 48:299-310. [PMID: 26718623 PMCID: PMC4843950 DOI: 10.1002/lsm.22464] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2015] [Indexed: 12/19/2022]
Abstract
Background Laparoscopic liver ablation therapy can be used for the treatment of primary and secondary liver malignancy. The increased incidence of cancer recurrence associated with this approach, has been attributed to the inability of monitoring the extent of ablated liver tissue. Methods The feasibility of assessing liver ablation with probe‐based confocal laser endomicroscopy (CLE) was studied in a porcine model of laparoscopic microwave liver ablation. Following the intravenous injection of the fluorophores fluorescein and indocyanine green, CLE images were recorded at 488 nm and 660 nm wavelength and compared to liver histology. Statistical analysis was performed to assess if fluorescence intensity change can predict the presence of ablated liver tissue. Results CLE imaging of fluorescein at 488 nm provided good visualization of the hepatic microvasculature; whereas, CLE imaging of indocyanine green at 660 nm enabled detailed visualization of hepatic sinusoid architecture and interlobular septations. Fluorescence intensity as measured in relative fluorescence units was found to be 75–100% lower in ablated compared to healthy liver regions. General linear mixed modeling and ROC analysis found the decrease in fluorescence to be statistically significant. Conclusion Laparoscopic, dual wavelength CLE imaging using two different fluorophores enables clinically useful visualization of multiple liver tissue compartments, in greater detail than is possible at a single wavelength. CLE imaging may provide valuable intraoperative information on the extent of laparoscopic liver ablation. Lasers Surg. Med. 48:299–310, 2016. © 2015 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Crispin Schneider
- Division of Surgery and Interventional Science, Royal Free Campus, University College London, Pond Street, NW3 2QG, London, UK
| | - Sean P Johnson
- Centre for Advanced Biomedical Imaging, Division of Medicine, University College London, London, United Kingdom
| | - Simon Walker-Samuel
- Centre for Advanced Biomedical Imaging, Division of Medicine, University College London, London, United Kingdom
| | - Kurinchi Gurusamy
- Division of Surgery and Interventional Science, Royal Free Campus, University College London, Pond Street, NW3 2QG, London, UK
| | - Matthew J Clarkson
- Division of Tissue Engineering and Biophotonics, Kings College London Dental Institute, London, United Kingdom
| | - Stephen Thompson
- Division of Tissue Engineering and Biophotonics, Kings College London Dental Institute, London, United Kingdom
| | - Yi Song
- Division of Tissue Engineering and Biophotonics, Kings College London Dental Institute, London, United Kingdom
| | - Johannes Totz
- Division of Tissue Engineering and Biophotonics, Kings College London Dental Institute, London, United Kingdom
| | - Richard J Cook
- Division of Tissue Engineering and Biophotonics, Kings College London Dental Institute, London, United Kingdom
| | - Adrien E Desjardins
- Department of Medical Physics and Bioengineering, University College London, London, United Kingdom
| | - David J Hawkes
- Centre for Medical Image Computing, University College London, London, United Kingdom
| | - Brian R Davidson
- Division of Surgery and Interventional Science, Royal Free Campus, University College London, Pond Street, NW3 2QG, London, UK
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50
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Mari JM, Xia W, West SJ, Desjardins AE. Interventional multispectral photoacoustic imaging with a clinical ultrasound probe for discriminating nerves and tendons: an ex vivo pilot study. J Biomed Opt 2015; 20:110503. [PMID: 26580699 PMCID: PMC5217182 DOI: 10.1117/1.jbo.20.11.110503] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 10/23/2015] [Indexed: 05/19/2023]
Abstract
Accurate and efficient identification of nerves is an essential component of peripheral nerve blocks. While ultrasound (US) imaging is increasingly used as a guidance modality, it often provides insufficient contrast for identifying nerves from surrounding tissues such as tendons. Electrical nerve stimulators can be used in conjunction with US imaging for discriminating nerves from surrounding tissues, but they are insufficient to reliably prevent neural punctures, so that alternative methods are highly desirable. In this study, an interventional multispectral photoacoustic (PA) imaging system was used to directly compare the signal amplitudes and spectra acquired from nerves and tendons ex vivo, for the first time. The results indicate that the system can provide significantly higher image contrast for discriminating nerves and tendons than that provided by US imaging. As such, photoacoustic imaging could be valuable as an adjunct to US for guiding peripheral nerve blocks.
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Affiliation(s)
- Jean Martial Mari
- University College London, Department of Medical Physics
and Biomedical Engineering, Gower Street, London WC1E 6BT, United Kingdom
- University of French Polynesia, GePaSud, Faa’a
98702, French, Polynesia, France
| | - Wenfeng Xia
- University College London, Department of Medical Physics
and Biomedical Engineering, Gower Street, London WC1E 6BT, United Kingdom
- Address all correspondence to: Wenfeng Xia,
| | - Simeon J. West
- University College Hospital, Department of Anaesthesia,
Main Theatres, Maple Bridge Link Corridor, Podium 3, 235 Euston Road, London NW1
2BU, United Kingdom
| | - Adrien E. Desjardins
- University College London, Department of Medical Physics
and Biomedical Engineering, Gower Street, London WC1E 6BT, United Kingdom
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