1
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Markwalder L, Gush R, Khan F, Murdoch CE, Krstajić N. In vivo laser speckle contrast imaging of microvascular blood perfusion using a chip-on-tip camera. iScience 2024; 27:109077. [PMID: 38375226 PMCID: PMC10875563 DOI: 10.1016/j.isci.2024.109077] [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: 02/08/2023] [Revised: 08/28/2023] [Accepted: 01/26/2024] [Indexed: 02/21/2024] Open
Abstract
Laser speckle contrast imaging (LSCI) is an important non-invasive capability for real-time imaging for tissue-perfusion assessment. Yet, the size and weight of current clinical standard LSCI instrumentation restricts usage to mainly peripheral skin perfusion. Miniaturization of LSCI could enable hand-held instrumentation to image internal organ/tissue to produce accurate speckle-perfusion maps. We characterized a 1mm2 chip-on-tip camera for LSCI of blood perfusion in vivo and with a flow model. A dedicated optical setup was built to compare chip-on-tip camera to a high specification reference camera (GS3) for LSCI. We compared LSCI performance using a calibration standard and a flow phantom. Subsequently the camera assessed placenta perfusion in a small animal model. Lastly, a human study was conducted on the perfusion in fingertips of 13-volunteers. We demonstrate that the chip-on-tip camera can perform wide-field, in vivo, LSCI of tissue perfusion with the ability to measure physiological blood flow changes comparable with a standard reference camera.
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Affiliation(s)
- Lukas Markwalder
- Systems Medicine, School of Medicine, University of Dundee, Ninewells Hospital & Medical School, DD1 9SY Dundee, UK
| | - Rodney Gush
- Moor Instruments, Millwey Rise Industrial Estate, Weycroft Avenue, EX13 5HU Axminster, UK
| | - Faisel Khan
- Systems Medicine, School of Medicine, University of Dundee, Ninewells Hospital & Medical School, DD1 9SY Dundee, UK
| | - Colin E. Murdoch
- Systems Medicine, School of Medicine, University of Dundee, Ninewells Hospital & Medical School, DD1 9SY Dundee, UK
| | - Nikola Krstajić
- School of Science and Engineering, Fulton Building, University of Dundee, DD1 4HN Dundee, UK
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2
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Eadie M, Liao J, Ageeli W, Nabi G, Krstajić N. Fiber Bundle Image Reconstruction Using Convolutional Neural Networks and Bundle Rotation in Endomicroscopy. Sensors (Basel) 2023; 23:2469. [PMID: 36904673 PMCID: PMC10007631 DOI: 10.3390/s23052469] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 02/15/2023] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
Fiber-bundle endomicroscopy has several recognized drawbacks, the most prominent being the honeycomb effect. We developed a multi-frame super-resolution algorithm exploiting bundle rotation to extract features and reconstruct underlying tissue. Simulated data was used with rotated fiber-bundle masks to create multi-frame stacks to train the model. Super-resolved images are numerically analyzed, which demonstrates that the algorithm can restore images with high quality. The mean structural similarity index measurement (SSIM) improved by a factor of 1.97 compared with linear interpolation. The model was trained using images taken from a single prostate slide, 1343 images were used for training, 336 for validation, and 420 for testing. The model had no prior information about the test images, adding to the robustness of the system. Image reconstruction was completed in 0.03 s for 256 × 256 images indicating future real-time performance is within reach. The combination of fiber bundle rotation and multi-frame image enhancement through machine learning has not been utilized before in an experimental setting but could provide a much-needed improvement to image resolution in practice.
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Affiliation(s)
- Matthew Eadie
- School of Science and Engineering, Centre for Medical Engineering and Technology, University of Dundee, Dundee DD1 4HN, UK
| | - Jinpeng Liao
- School of Science and Engineering, Centre for Medical Engineering and Technology, University of Dundee, Dundee DD1 4HN, UK
| | - Wael Ageeli
- School of Medicine, Centre for Medical Engineering and Technology, University of Dundee, Dundee DD1 9SY, UK
- Diagnostic Radiology Department, College of Applied Medical Sciences, Jazan University, Al Maarefah Rd, P.O. Box 114, Jazan 45142, Saudi Arabia
| | - Ghulam Nabi
- School of Medicine, Centre for Medical Engineering and Technology, University of Dundee, Dundee DD1 9SY, UK
| | - Nikola Krstajić
- School of Science and Engineering, Centre for Medical Engineering and Technology, University of Dundee, Dundee DD1 4HN, UK
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3
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Kufcsák A, Bagnaninchi P, Erdogan AT, Henderson RK, Krstajić N. Time-resolved spectral-domain optical coherence tomography with CMOS SPAD sensors. Opt Express 2021; 29:18720-18733. [PMID: 34154122 DOI: 10.1364/oe.422648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 05/14/2021] [Indexed: 06/13/2023]
Abstract
We present a first spectral-domain optical coherence tomography (SD-OCT) system deploying a complementary metal-oxide-semiconductor (CMOS) single-photon avalanche diode (SPAD) based, time-resolved line sensor. The sensor with 1024 pixels achieves a sensitivity of 87 dB at an A-scan rate of 1 kHz using a supercontinuum laser source with a repetition rate of 20 MHz, 38 nm bandwidth, and 2 mW power at 850 nm centre wavelength. In the time-resolved mode of the sensor, the system combines low-coherence interferometry (LCI) and massively parallel time-resolved single-photon counting to control the detection of interference spectra on the single-photon level based on the time-of-arrival of photons. For proof of concept demonstration of the combined detection scheme we show the acquisition of time-resolved interference spectra and the reconstruction of OCT images from selected time bins. Then, we exemplify the temporal discrimination feature with 50 ps time resolution and 249 ps timing uncertainty by removing unwanted reflections from along the optical path at a 30 mm distance from the sample. The current limitations of the proposed technique in terms of sensor parameters are analysed and potential improvements are identified for advanced photonic applications.
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4
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Mills B, Megia-Fernandez A, Norberg D, Duncan S, Marshall A, Akram AR, Quinn T, Young I, Bruce AM, Scholefield E, Williams GOS, Krstajić N, Choudhary TR, Parker HE, Tanner MG, Harrington K, Wood HAC, Birks TA, Knight JC, Haslett C, Dhaliwal K, Bradley M, Ucuncu M, Stone JM. Molecular detection of Gram-positive bacteria in the human lung through an optical fiber-based endoscope. Eur J Nucl Med Mol Imaging 2020; 48:800-807. [PMID: 32915268 PMCID: PMC7485201 DOI: 10.1007/s00259-020-05021-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [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: 05/08/2020] [Accepted: 08/31/2020] [Indexed: 12/13/2022]
Abstract
Purpose The relentless rise in antimicrobial resistance is a major societal challenge and requires, as part of its solution, a better understanding of bacterial colonization and infection. To facilitate this, we developed a highly efficient no-wash red optical molecular imaging agent that enables the rapid, selective, and specific visualization of Gram-positive bacteria through a bespoke optical fiber–based delivery/imaging endoscopic device. Methods We rationally designed a no-wash, red, Gram-positive-specific molecular imaging agent (Merocy-Van) based on vancomycin and an environmental merocyanine dye. We demonstrated the specificity and utility of the imaging agent in escalating in vitro and ex vivo whole human lung models (n = 3), utilizing a bespoke fiber–based delivery and imaging device, coupled to a wide-field, two-color endomicroscopy system. Results The imaging agent (Merocy-Van) was specific to Gram-positive bacteria and enabled no-wash imaging of S. aureus within the alveolar space of whole ex vivo human lungs within 60 s of delivery into the field-of-view, using the novel imaging/delivery endomicroscopy device. Conclusion This platform enables the rapid and specific detection of Gram-positive bacteria in the human lung. Electronic supplementary material The online version of this article (10.1007/s00259-020-05021-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bethany Mills
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK.
| | - Alicia Megia-Fernandez
- School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, UK
| | - Dominic Norberg
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Sheelagh Duncan
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Adam Marshall
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Ahsan R Akram
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Thomas Quinn
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Irene Young
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Annya M Bruce
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Emma Scholefield
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Gareth O S Williams
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Nikola Krstajić
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Tushar R Choudhary
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK.,The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK
| | - Helen E Parker
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK.,Department of Applied Physics, Royal Institute of Technology, KTH, SE-106 91, Stockholm, Sweden
| | - Michael G Tanner
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK.,Scottish Universities Physics Alliance (SUPA), Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - Kerrianne Harrington
- Centre for Photonics and Photonic Materials, Department of Physics, University of Bath, Bath, BA2 7AY, UK
| | - Harry A C Wood
- Centre for Photonics and Photonic Materials, Department of Physics, University of Bath, Bath, BA2 7AY, UK
| | - Timothy A Birks
- Centre for Photonics and Photonic Materials, Department of Physics, University of Bath, Bath, BA2 7AY, UK
| | - Jonathan C Knight
- Centre for Photonics and Photonic Materials, Department of Physics, University of Bath, Bath, BA2 7AY, UK
| | - Christopher Haslett
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Kevin Dhaliwal
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Mark Bradley
- School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, UK.
| | - Muhammed Ucuncu
- School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, UK. .,Department of Analytical Chemistry, Faculty of Pharmacy, Izmir Katip Celebi University, Izmir, Turkey.
| | - James M Stone
- Centre for Photonics and Photonic Materials, Department of Physics, University of Bath, Bath, BA2 7AY, UK.
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5
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Megia-Fernandez A, Mills B, Michels C, Chankeshwara SV, Krstajić N, Haslett C, Dhaliwal K, Bradley M. Bimodal fluorogenic sensing of matrix proteolytic signatures in lung cancer. Org Biomol Chem 2019; 16:8056-8063. [PMID: 30175355 PMCID: PMC6238727 DOI: 10.1039/c8ob01790e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Optical biosensing based on the activation of fluorescent reporters offers a powerful methodology for the real-time molecular interrogation of pathology. Here we report a first-in-class, bimodal fluorescent reporter strategy for the simultaneous and highly specific detection of two independent proteases (thrombin and matrix metalloproteases (MMPs)) pivotal in the fibroproliferative process surrounding lung cancer, based on a dual, multiplexing, peptide FRET system. This sophisticated synthetic smartprobe, with a molecular weight of 6 kDa, contains two independent fluorophores and quenchers that generate photonic signatures at two specific wavelengths upon activation by target enzymes within human lung cancer tissue.
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Affiliation(s)
- Alicia Megia-Fernandez
- School of Chemistry and the EPSRC IRC Proteus, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, UK.
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6
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Pedretti E, Tanner MG, Choudhary TR, Krstajić N, Megia-Fernandez A, Henderson RK, Bradley M, Thomson RR, Girkin JM, Dhaliwal K, Dalgarno PA. High-speed dual color fluorescence lifetime endomicroscopy for highly-multiplexed pulmonary diagnostic applications and detection of labeled bacteria. Biomed Opt Express 2019; 10:181-195. [PMID: 30775092 PMCID: PMC6363193 DOI: 10.1364/boe.10.000181] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 11/21/2018] [Accepted: 11/24/2018] [Indexed: 05/03/2023]
Abstract
We present a dual-color laser scanning endomicroscope capable of fluorescence lifetime endomicroscopy at one frame per second (FPS). The scanning system uses a coherent imaging fiber with 30,000 cores. High-speed lifetime imaging is achieved by distributing the signal over an array of 1024 parallel single-photon avalanche diode detectors (SPADs), minimizing detection dead-time maximizing the number of photons detected per excitation pulse without photon pile-up to achieve the high frame rate. This also enables dual color fluorescence imaging by temporally shifting the dual excitation lasers, with respect to each other, to separate the two spectrally distinct fluorescent decays in time. Combining the temporal encoding, to provide spectral separation, with lifetime measurements we show a one FPS, multi-channel endomicroscopy platform for clinical applications and diagnosis. We demonstrate the potential of the system by imaging SmartProbe labeled bacteria in ex vivo samples of human lung using lifetime to differentiate bacterial fluorescence from the strong background lung autofluorescence which was used to provide structural information.
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Affiliation(s)
- Ettore Pedretti
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot–Watt University, Edinburgh EH14 4AS,
UK
- EPSRC Proteus Hub, Centre for Inflammation Research, Queen’s Medical Research Centre, University of Edinburgh, Edinburgh EH16 4TJ,
UK
- Currently with the Leibniz-Institute für Astrophysik Potsdam, Potsdam,
Germany
| | - Michael G. Tanner
- Scottish Universities Physics Alliance (SUPA), Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot–Watt University, Edinburgh EH14 4AS,
UK
- EPSRC Proteus Hub, Centre for Inflammation Research, Queen’s Medical Research Centre, University of Edinburgh, Edinburgh EH16 4TJ,
UK
| | - Tushar R. Choudhary
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot–Watt University, Edinburgh EH14 4AS,
UK
- EPSRC Proteus Hub, Centre for Inflammation Research, Queen’s Medical Research Centre, University of Edinburgh, Edinburgh EH16 4TJ,
UK
| | - Nikola Krstajić
- EPSRC Proteus Hub, Centre for Inflammation Research, Queen’s Medical Research Centre, University of Edinburgh, Edinburgh EH16 4TJ,
UK
- Institute for Integrated Micro and Nano Systems, School of Engineering, University of Edinburgh, Edinburgh EH9 3FF,
UK
- Currently with the University of Dundee, School of Science and Engineering, Dundee,
UK
| | | | - Robert K. Henderson
- Institute for Integrated Micro and Nano Systems, School of Engineering, University of Edinburgh, Edinburgh EH9 3FF,
UK
| | - Mark Bradley
- EPSRC Proteus Hub, Centre for Inflammation Research, Queen’s Medical Research Centre, University of Edinburgh, Edinburgh EH16 4TJ,
UK
- EaStChem, School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ,
UK
| | - Robert R. Thomson
- Scottish Universities Physics Alliance (SUPA), Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot–Watt University, Edinburgh EH14 4AS,
UK
- EPSRC Proteus Hub, Centre for Inflammation Research, Queen’s Medical Research Centre, University of Edinburgh, Edinburgh EH16 4TJ,
UK
| | - John M. Girkin
- Department of Physics, University of Durham, Durham DH1 3LE,
UK
| | - Kevin Dhaliwal
- EPSRC Proteus Hub, Centre for Inflammation Research, Queen’s Medical Research Centre, University of Edinburgh, Edinburgh EH16 4TJ,
UK
| | - Paul A. Dalgarno
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot–Watt University, Edinburgh EH14 4AS,
UK
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7
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Poland SP, Chan GK, Levitt JA, Krstajić N, Erdogan AT, Henderson RK, Parsons M, Ameer-Beg SM. Multifocal multiphoton volumetric imaging approach for high-speed time-resolved Förster resonance energy transfer imaging in vivo. Opt Lett 2018; 43:6057-6060. [PMID: 30548010 PMCID: PMC6410918 DOI: 10.1364/ol.43.006057] [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] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 10/29/2018] [Accepted: 11/01/2018] [Indexed: 05/29/2023]
Abstract
In this Letter, we will discuss the development of a multifocal multiphoton fluorescent lifetime imaging system where four individual fluorescent intensity and lifetime planes are acquired simultaneously, allowing us to obtain volumetric data without the need for sequential scanning at different axial depths. Using a phase-only spatial light modulator (SLM) with an appropriate algorithm to generate a holographic pattern, we project a beamlet array within a sample volume of a size, which can be preprogrammed by the user. We demonstrate the capabilities of the system to image live-cell interactions. While only four planes are shown, this technique can be rescaled to a large number of focal planes, enabling full 3D acquisition and reconstruction.
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Affiliation(s)
- Simon P. Poland
- Comprehensive Cancer Centre, School of Cancer and Pharmaceutical Sciences, Guy's Campus, King's College London, UK
| | - Grace K. Chan
- Randall Centre for Cell and Molecular Biophysics, Guy’s Campus, Kings College, UK
| | - James A. Levitt
- Comprehensive Cancer Centre, School of Cancer and Pharmaceutical Sciences, Guy's Campus, King's College London, UK
- Randall Centre for Cell and Molecular Biophysics, Guy’s Campus, Kings College, UK
| | - Nikola Krstajić
- Institute for Integrated Micro and Nano Systems, School of Engineering, University of Edinburgh, Edinburgh, UK
- EPSRC IRC “Hub” in Optical Molecular Sensing & Imaging, Centre for Inflammation Research, Queen’s Medical Research Institute, 47 Little France Crescent, University of Edinburgh, Edinburgh, UK
| | - Ahmet T. Erdogan
- Institute for Integrated Micro and Nano Systems, School of Engineering, University of Edinburgh, Edinburgh, UK
| | - Robert K. Henderson
- Institute for Integrated Micro and Nano Systems, School of Engineering, University of Edinburgh, Edinburgh, UK
| | - Maddy Parsons
- Randall Centre for Cell and Molecular Biophysics, Guy’s Campus, Kings College, UK
| | - Simon M. Ameer-Beg
- Comprehensive Cancer Centre, School of Cancer and Pharmaceutical Sciences, Guy's Campus, King's College London, UK
- Randall Centre for Cell and Molecular Biophysics, Guy’s Campus, Kings College, UK
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8
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Krstajić N, Mills B, Murray I, Marshall A, Norberg D, Craven TH, Emanuel P, Choudhary TR, Williams GOS, Scholefield E, Akram AR, Davie A, Hirani N, Bruce A, Moore A, Bradley M, Dhaliwal K. Low-cost high sensitivity pulsed endomicroscopy to visualize tricolor optical signatures. J Biomed Opt 2018; 23:1-12. [PMID: 29992799 DOI: 10.1117/1.jbo.23.7.076005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [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: 10/23/2017] [Accepted: 05/16/2018] [Indexed: 05/20/2023]
Abstract
A highly sensitive, modular three-color fluorescence endomicroscopy imaging platform spanning the visible to near-infrared (NIR) range is demonstrated. Light-emitting diodes (LEDs) were sequentially pulsed along with the camera acquisition to provide up to 20 frames per second (fps) three-color imaging performance or 60 fps single color imaging. The system was characterized for bacterial and cellular molecular imaging in ex vivo human lung tissue and for bacterial and indocyanine green imaging in ex vivo perfused sheep lungs. A practical method to reduce background tissue autofluorescence is also proposed. The platform was clinically translated into six patients with pulmonary disease to delineate healthy, cancerous, and fibrotic tissue autofluorescent structures. The instrument is the most broadband clinical endomicroscopy system developed to date (covering visible to the NIR, 500 to 900 nm) and demonstrates significant potential for future clinical utility due to its low cost and modular capability to suit a wide variety of molecular imaging applications.
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Affiliation(s)
- Nikola Krstajić
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
- University of Edinburgh, Institute for Integrated Micro and Nano Systems, School of Engineering, Edi, United Kingdom
- University of Dundee, School of Science and Engineering, Dundee, United Kingdom
| | - Bethany Mills
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
| | - Ian Murray
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
| | - Adam Marshall
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
| | - Dominic Norberg
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
| | - Thomas H Craven
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
| | - Philip Emanuel
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
| | - Tushar R Choudhary
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
- Heriot-Watt University, Institute of Biological Chemistry, Biophysics and Bioengineering, Edinburgh, United Kingdom
| | - Gareth O S Williams
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
| | - Emma Scholefield
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
| | - Ahsan R Akram
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
| | - Andrew Davie
- Royal Infirmary of Edinburgh, NHS Lothian, Department of Medical Physics, Edinburgh, United Kingdom
| | - Nik Hirani
- University of Edinburgh, Department of Respiratory Medicine, Edinburgh, United Kingdom
| | - Annya Bruce
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
| | - Anne Moore
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
| | - Mark Bradley
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
- University of Edinburgh, School of Chemistry, EaStChem, Edinburgh, United Kingdom
| | - Kevin Dhaliwal
- University of Edinburgh, Queen's Medical Research Institute, EPSRC IRC Hub in Optical Molecular Sens, United Kingdom
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9
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Kufcsák A, Erdogan A, Walker R, Ehrlich K, Tanner M, Megia-Fernandez A, Scholefield E, Emanuel P, Dhaliwal K, Bradley M, Henderson RK, Krstajić N. Time-resolved spectroscopy at 19,000 lines per second using a CMOS SPAD line array enables advanced biophotonics applications. Opt Express 2017; 25:11103-11123. [PMID: 28788793 DOI: 10.1364/oe.25.011103] [Citation(s) in RCA: 9] [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: 05/10/2023]
Abstract
A SPAD-based line sensor fabricated in 130 nm CMOS technology capable of acquiring time-resolved fluorescence spectra (TRFS) in 8.3 milliseconds is presented. To the best of our knowledge, this is the fastest time correlated single photon counting (TCSPC) TRFS acquisition reported to date. The line sensor is an upgrade to our prior work and incorporates: i) parallelized interface from sensor to surrounding circuitry enabling high line rate to the PC (19,000 lines/s) and ii) novel time-gating architecture where detected photons in the OFF region are rejected digitally after the output stage of the SPAD. The time-gating architecture was chosen to avoid electrical transients on the SPAD high voltage supplies when gating is achieved by excess bias modulation. The time-gate has an adjustable location and time window width allowing the user to focus on time-events of interest. On-chip integrated center-of-mass (CMM) calculations provide efficient acquisition of photon arrivals and direct lifetime estimation of fluorescence decays. Furthermore, any of the SPC, TCSPC and on-chip CMM modes can be used in conjunction with the time-gating. The higher readout rate and versatile architecture greatly empower the user and will allow widespread applications across many techniques and disciplines. Here we focused on 3 examples of TRFS and time-gated Raman spectroscopy: i) kinetics of chlorophyll A fluorescence from an intact leaf; ii) kinetics of a thrombin biosensor FRET probe from quenched to fluorescence states; iii) ex vivo mouse lung tissue autofluorescence TRFS; iv) time-gated Raman spectroscopy of toluene at 3056 cm-1 peak. To the best of our knowledge, we detect spectrally for the first time the fast rise in fluorescence lifetime of chlorophyll A in a measurement over single fluorescent transient.
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10
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Chandrasekharan HK, Izdebski F, Gris-Sánchez I, Krstajić N, Walker R, Bridle HL, Dalgarno PA, MacPherson WN, Henderson RK, Birks TA, Thomson RR. Multiplexed single-mode wavelength-to-time mapping of multimode light. Nat Commun 2017; 8:14080. [PMID: 28120822 PMCID: PMC5288496 DOI: 10.1038/ncomms14080] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [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: 04/19/2016] [Accepted: 11/25/2016] [Indexed: 11/09/2022] Open
Abstract
When an optical pulse propagates along an optical fibre, different wavelengths travel at different group velocities. As a result, wavelength information is converted into arrival-time information, a process known as wavelength-to-time mapping. This phenomenon is most cleanly observed using a single-mode fibre transmission line, where spatial mode dispersion is not present, but the use of such fibres restricts possible applications. Here we demonstrate that photonic lanterns based on tapered single-mode multicore fibres provide an efficient way to couple multimode light to an array of single-photon avalanche detectors, each of which has its own time-to-digital converter for time-correlated single-photon counting. Exploiting this capability, we demonstrate the multiplexed single-mode wavelength-to-time mapping of multimode light using a multicore fibre photonic lantern with 121 single-mode cores, coupled to 121 detectors on a 32 × 32 detector array. This work paves the way to efficient multimode wavelength-to-time mapping systems with the spectral performance of single-mode systems. Photonic lanterns are made by merging several single-mode cores into one multimode core. Here, the authors show this type of structure can both perform wavelength-to-time mapping of multimode states of light and couple such light to an array of single-photon avalanche detectors.
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Affiliation(s)
- Harikumar K Chandrasekharan
- Scottish Universities Physics Alliance (SUPA), Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK.,Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Frauke Izdebski
- Scottish Universities Physics Alliance (SUPA), Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | | | - Nikola Krstajić
- Institute for Integrated Micro and Nano Systems, School of Engineering, University of Edinburgh, Edinburgh EH9 3FF, UK
| | - Richard Walker
- Institute for Integrated Micro and Nano Systems, School of Engineering, University of Edinburgh, Edinburgh EH9 3FF, UK
| | - Helen L Bridle
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Paul A Dalgarno
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - William N MacPherson
- Scottish Universities Physics Alliance (SUPA), Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Robert K Henderson
- Institute for Integrated Micro and Nano Systems, School of Engineering, University of Edinburgh, Edinburgh EH9 3FF, UK
| | - Tim A Birks
- Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Robert R Thomson
- Scottish Universities Physics Alliance (SUPA), Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
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11
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Poland SP, Erdogan AT, Krstajić N, Levitt J, Devauges V, Walker RJ, Li DDU, Ameer-Beg SM, Henderson RK. New high-speed centre of mass method incorporating background subtraction for accurate determination of fluorescence lifetime. Opt Express 2016; 24:6899-915. [PMID: 27136986 DOI: 10.1364/oe.24.006899] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We demonstrate an implementation of a centre-of-mass method (CMM) incorporating background subtraction for use in multifocal fluorescence lifetime imaging microscopy to accurately determine fluorescence lifetime in live cell imaging using the Megaframe camera. The inclusion of background subtraction solves one of the major issues associated with centre-of-mass approaches, namely the sensitivity of the algorithm to background signal. The algorithm, which is predominantly implemented in hardware, provides real-time lifetime output and allows the user to effectively condense large amounts of photon data. Instead of requiring the transfer of thousands of photon arrival times, the lifetime is simply represented by one value which allows the system to collect data up to limit of pulse pile-up without any limitations on data transfer rates. In order to evaluate the performance of this new CMM algorithm with existing techniques (i.e. rapid lifetime determination and Levenburg-Marquardt), we imaged live MCF-7 human breast carcinoma cells transiently transfected with FRET standards. We show that, it offers significant advantages in terms of lifetime accuracy and insensitivity to variability in dark count rate (DCR) between Megaframe camera pixels. Unlike other algorithms no prior knowledge of the expected lifetime is required to perform lifetime determination. The ability of this technique to provide real-time lifetime readout makes it extremely useful for a number of applications.
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12
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Rocca FMD, Nedbal J, Tyndall D, Krstajić N, Li DDU, Ameer-Beg SM, Henderson RK. Real-time fluorescence lifetime actuation for cell sorting using a CMOS SPAD silicon photomultiplier. Opt Lett 2016; 41:673-6. [PMID: 26872160 DOI: 10.1364/ol.41.000673] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [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
Time-correlated single photon counting (TCSPC) is a fundamental fluorescence lifetime measurement technique offering high signal to noise ratio (SNR). However, its requirement for complex software algorithms for histogram processing restricts throughput in flow cytometers and prevents on-the-fly sorting of cells. We present a single-point digital silicon photomultiplier (SiPM) detector accomplishing real-time fluorescence lifetime-activated actuation targeting cell sorting applications in flow cytometry. The sensor also achieves burst-integrated fluorescence lifetime (BIFL) detection by TCSPC. The SiPM is a single-chip complementary metal-oxide-semiconductor (CMOS) sensor employing a 32×32 single-photon avalanche diode (SPAD) array and eight pairs of time-interleaved time to digital converters (TI-TDCs) with a 50 ps minimum timing resolution. The sensor's pile-up resistant embedded center of mass method (CMM) processor accomplishes low-latency measurement and thresholding of fluorescence lifetime. A digital control signal is generated with a 16.6 μs latency for cell sorter actuation allowing a maximum cell throughput of 60,000 cells per second and an error rate of 0.6%.
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Poland SP, Levitt JA, Krstajić N, Erdogen A, Walker RJ, Devauges V, Ng T, Henderson RK, Ameer-Beg SM. A Multifocal Multiphoton Volumetric Imaging Technique for High Speed Time-Resolved FRET Imaging in vivo. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.920] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Krstajić N, Poland S, Levitt J, Walker R, Erdogan A, Ameer-Beg S, Henderson RK. 0.5 billion events per second time correlated single photon counting using CMOS SPAD arrays. Opt Lett 2015; 40:4305-8. [PMID: 26371922 DOI: 10.1364/ol.40.004305] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We present a digital architecture for fast acquisition of time correlated single photon counting (TCSPC) events from a 32×32 complementary metal oxide semiconductor (CMOS) single photon avalanche detector (SPAD) array (Megaframe) to the computer memory. Custom firmware was written to transmit event codes from 1024-TCSPC-enabled pixels for fast transfer of TCSPC events. Our 1024-channel TCSPC system is capable of acquiring up to 0.5×10(9) TCSPC events per second with 16 histogram bins spanning a 14 ns width. Other options include 320×10(6) TCSPC events per second with 256 histogram bins spanning either a 14 or 56 ns time window. We present a wide-field fluorescence microscopy setup demonstrating fast fluorescence lifetime data acquisition. To the best of our knowledge, this is the fastest direct TCSPC transfer from a single photon counting device to the computer to date.
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Krstajić N, Levitt J, Poland S, Ameer-Beg S, Henderson R. 256 × 2 SPAD line sensor for time resolved fluorescence spectroscopy. Opt Express 2015; 23:5653-69. [PMID: 25836796 DOI: 10.1364/oe.23.005653] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We present a CMOS chip 256 × 2 single photon avalanche diode (SPAD) line sensor, 23.78 µm pitch, 43.7% fill factor, custom designed for time resolved emission spectroscopy (TRES). Integrating time-to-digital converters (TDCs) implement on-chip mono-exponential fluorescence lifetime pre-calculation allowing timing of 65k photons/pixel at 200 Hz line rate at 40 ps resolution using centre-of-mass method (CMM). Per pixel time-correlated single-photon counting (TCSPC) histograms can also be generated with 320 ps bin resolution. We characterize performance in terms of dark count rate, instrument response function and lifetime uniformity for a set of fluorophores with lifetimes ranging from 4 ns to 6 ns. Lastly, we present fluorescence lifetime spectra of multicolor microspheres and skin autofluorescence acquired using a custom built spectrometer. In TCSPC mode, time-resolved spectra are acquired within 5 minutes whilst in CMM mode spectral lifetime signatures are acquired within 2 ms for fluorophore in cuvette and 200 ms for skin autofluorescence. We demonstrate CMOS line sensors to be a versatile tool for time-resolved fluorescence spectroscopy by providing parallelized and flexible spectral detection of fluorescence decay.
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Gariepy G, Krstajić N, Henderson R, Li C, Thomson RR, Buller GS, Heshmat B, Raskar R, Leach J, Faccio D. Erratum: Single-photon sensitive light-in-flight imaging. Nat Commun 2015; 6:6408. [PMID: 25711544 PMCID: PMC4348700 DOI: 10.1038/ncomms7408] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Poland SP, Krstajić N, Monypenny J, Coelho S, Tyndall D, Walker RJ, Devauges V, Richardson J, Dutton N, Barber P, Li DDU, Suhling K, Ng T, Henderson RK, Ameer-Beg SM. A high speed multifocal multiphoton fluorescence lifetime imaging microscope for live-cell FRET imaging. Biomed Opt Express 2015; 6:277-96. [PMID: 25780724 PMCID: PMC4354599 DOI: 10.1364/boe.6.000277] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 11/28/2014] [Accepted: 11/30/2014] [Indexed: 05/18/2023]
Abstract
We demonstrate diffraction limited multiphoton imaging in a massively parallel, fully addressable time-resolved multi-beam multiphoton microscope capable of producing fluorescence lifetime images with sub-50ps temporal resolution. This imaging platform offers a significant improvement in acquisition speed over single-beam laser scanning FLIM by a factor of 64 without compromising in either the temporal or spatial resolutions of the system. We demonstrate FLIM acquisition at 500 ms with live cells expressing green fluorescent protein. The applicability of the technique to imaging protein-protein interactions in live cells is exemplified by observation of time-dependent FRET between the epidermal growth factor receptor (EGFR) and the adapter protein Grb2 following stimulation with the receptor ligand. Furthermore, ligand-dependent association of HER2-HER3 receptor tyrosine kinases was observed on a similar timescale and involved the internalisation and accumulation or receptor heterodimers within endosomes. These data demonstrate the broad applicability of this novel FLIM technique to the spatio-temporal dynamics of protein-protein interaction.
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Affiliation(s)
- Simon P. Poland
- Division of Cancer Studies, Guy’s Campus, Kings College, London,
UK
- Randall Division of Cell and Molecular Biophysics, Guy’s Campus, Kings College, London,
UK
| | - Nikola Krstajić
- Institute for Integrated Micro and Nano Systems, School of Engineering, University of Edinburgh, Edinburgh,
UK
| | - James Monypenny
- Division of Cancer Studies, Guy’s Campus, Kings College, London,
UK
- Randall Division of Cell and Molecular Biophysics, Guy’s Campus, Kings College, London,
UK
| | - Simao Coelho
- Division of Cancer Studies, Guy’s Campus, Kings College, London,
UK
- Randall Division of Cell and Molecular Biophysics, Guy’s Campus, Kings College, London,
UK
| | - David Tyndall
- Institute for Integrated Micro and Nano Systems, School of Engineering, University of Edinburgh, Edinburgh,
UK
| | - Richard J. Walker
- Institute for Integrated Micro and Nano Systems, School of Engineering, University of Edinburgh, Edinburgh,
UK
- Photon-Force Ltd., Edinburgh,
UK
| | - Viviane Devauges
- Division of Cancer Studies, Guy’s Campus, Kings College, London,
UK
- Randall Division of Cell and Molecular Biophysics, Guy’s Campus, Kings College, London,
UK
| | - Justin Richardson
- Institute for Integrated Micro and Nano Systems, School of Engineering, University of Edinburgh, Edinburgh,
UK
- Photon-Force Ltd., Edinburgh,
UK
| | - Neale Dutton
- Institute for Integrated Micro and Nano Systems, School of Engineering, University of Edinburgh, Edinburgh,
UK
| | - Paul Barber
- Gray Institute for Radiation Oncology & Biology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ
UK
| | - David Day-Uei Li
- Strathclyde Institute of Pharmacy and Biomedical Sciences, 161 Cathedral Street, Glasgow, G4 0RE,
UK
| | - Klaus Suhling
- Department of Physics, King's College London, Strand, London,
UK
| | - Tony Ng
- Division of Cancer Studies, Guy’s Campus, Kings College, London,
UK
- Randall Division of Cell and Molecular Biophysics, Guy’s Campus, Kings College, London,
UK
- UCL Cancer Institute, Paul O'Gorman Building, University College London, London WC1E 6DD,
UK
| | - Robert K. Henderson
- Institute for Integrated Micro and Nano Systems, School of Engineering, University of Edinburgh, Edinburgh,
UK
| | - Simon M. Ameer-Beg
- Division of Cancer Studies, Guy’s Campus, Kings College, London,
UK
- Randall Division of Cell and Molecular Biophysics, Guy’s Campus, Kings College, London,
UK
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Spasojević M, Krstajić N, Spasojević P, Ribić-Zelenović L. Modelling current efficiency in an electrochemical hypochlorite reactor. Chem Eng Res Des 2015. [DOI: 10.1016/j.cherd.2014.07.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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19
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Poland SP, Krstajić N, Coelho S, Tyndall D, Walker RJ, Devauges V, Morton PE, Nicholas NS, Richardson J, Li DDU, Suhling K, Wells CM, Parsons M, Henderson RK, Ameer-Beg SM. Time-resolved multifocal multiphoton microscope for high speed FRET imaging in vivo. Opt Lett 2014; 39:6013-6. [PMID: 25361143 DOI: 10.1364/ol.39.006013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Imaging the spatiotemporal interaction of proteins in vivo is essential to understanding the complexities of biological systems. The highest accuracy monitoring of protein-protein interactions is achieved using Förster resonance energy transfer (FRET) measured by fluorescence lifetime imaging, with measurements taking minutes to acquire a single frame, limiting their use in dynamic live cell systems. We present a diffraction limited, massively parallel, time-resolved multifocal multiphoton microscope capable of producing fluorescence lifetime images with 55 ps time-resolution, giving improvements in acquisition speed of a factor of 64. We present demonstrations with FRET imaging in a model cell system and demonstrate in vivo FLIM using a GTPase biosensor in the zebrafish embryo.
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Poland SP, Krstajić N, Knight RD, Henderson RK, Ameer-Beg SM. Development of a doubly weighted Gerchberg-Saxton algorithm for use in multibeam imaging applications. Opt Lett 2014; 39:2431-2434. [PMID: 24979011 DOI: 10.1364/ol.39.002431] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report on the development of a doubly weighted Gerchberg-Saxton algorithm (DWGS) to enable generation of uniform beamlet arrays with a spatial light modulator (SLM) for use in multiphoton multifocal imaging applications. The algorithm incorporates the WGS algorithm as well as feedback of fluorescence signals from the sample measured with a single-photon avalanche diode (SPAD) detector array. This technique compensates for issues associated with nonuniform illumination onto the SLM, the effects due to aberrations and the variability in gain between detectors within the SPAD array to generate a uniformly illuminated multiphoton fluorescence image. We demonstrate the use of the DWGS with a number of beamlet array patterns to image muscle fibers of a 5-day-old fixed zebrafish larvae.
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Abstract
We present a simple method applicable to common-path Fourier domain optical coherence tomography (OCT) in which the tissue surface is used as the reference arm. We propose using aluminium hydroxide powder as a potential tissue surface diffuser to allow wider application of this method. This technique allows one to avoid placing a reference arm reflective element, such as glass plate, on tissue, and intrinsically avoids both coherent and complex conjugate mirror artifacts associated with glass plates. Aluminium hydroxide can be sprayed onto tissue using spray nozzles commonly found in endoscopes. The sensitivity of the tissue reference arm common-path OCT image is 94 dB for a 50-[micro sign]s charge-coupled device integration time, and 97.5 dB for a 200-[micro sign]s CCD integration time.
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Affiliation(s)
- Nikola Krstajić
- University of Edinburgh, School of Engineering, Institute for Integrated Micro and Nano Systems, Faraday Building, Kings Buildings, Mayfield Road, Edinburgh EH93JL, United Kingdom
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Abstract
3D measurement of optical attenuation is of interest in a variety of fields of biomedical importance, including spectrophotometry, optical projection tomography (OPT) and analysis of 3D radiation dosimeters. Accurate, precise and economical 3D measurements of optical density (OD) are a crucial step in enabling 3D radiation dosimeters to enter wider use in clinics. Polymer gels and Fricke gels, as well as dosimeters not based around gels, have been characterized for 3D dosimetry over the last two decades. A separate problem is the verification of the best readout method. A number of different imaging modalities (magnetic resonance imaging (MRI), optical CT, x-ray CT and ultrasound) have been suggested for the readout of information from 3D dosimeters. To date only MRI and laser-based optical CT have been characterized in detail. This paper describes some initial steps we have taken in establishing charge coupled device (CCD)-based optical CT as a viable alternative to MRI for readout of 3D radiation dosimeters. The main advantage of CCD-based optical CT over traditional laser-based optical CT is a speed increase of at least an order of magnitude, while the simplicity of its architecture would lend itself to cheaper implementation than both MRI and laser-based optical CT if the camera itself were inexpensive enough. Specifically, we study the following aspects of optical metrology, using high quality test targets: (i) calibration and quality of absorbance measurements and the camera requirements for 3D dosimetry; (ii) the modulation transfer function (MTF) of individual projections; (iii) signal-to-noise ratio (SNR) in the projection and reconstruction domains; (iv) distortion in the projection domain, depth-of-field (DOF) and telecentricity. The principal results for our current apparatus are as follows: (i) SNR of optical absorbance in projections is better than 120:1 for uniform phantoms in absorbance range 0.3 to 1.6 (and better than 200:1 for absorbances 1.0 to 3.5 with the test target and a novel absorbance range extension method), (ii) the spatial resolution is shown to be at worst 0.5 mm (and often better than this) with an associated DOF of 8 cm, (iii) the SNR of uniform phantoms in reconstruction domain is above 80:1 (one standard deviation) over an absorbance dynamic range of 0.3 to 1.6, (iv) the apparatus is telecentric and without distortion. Finally, a sample scan and reconstruction of a scan of a PRESAGE dosimeter are shown, demonstrating the capabilities of the apparatus.
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Affiliation(s)
- Nikola Krstajić
- Department of Physics, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
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Abstract
3D measurement of optical attenuation is of interest in a variety of fields of biomedical importance, including spectrophotometry, optical projection tomography (OPT) and analysis of 3D radiation dosimeters. Accurate, precise and economical 3D measurements of optical density (OD) are a crucial step in enabling 3D radiation dosimeters to enter wider use in clinics. Polymer gels and Fricke gels, as well as dosimeters not based around gels, have been characterized for 3D dosimetry over the last two decades. A separate problem is the verification of the best readout method. A number of different imaging modalities (magnetic resonance imaging (MRI), optical CT, x-ray CT and ultrasound) have been suggested for the readout of information from 3D dosimeters. To date only MRI and laser-based optical CT have been characterized in detail. This paper describes some initial steps we have taken in establishing charge coupled device (CCD)-based optical CT as a viable alternative to MRI for readout of 3D radiation dosimeters. The main advantage of CCD-based optical CT over traditional laser-based optical CT is a speed increase of at least an order of magnitude, while the simplicity of its architecture would lend itself to cheaper implementation than both MRI and laser-based optical CT if the camera itself were inexpensive enough. Specifically, we study the following aspects of optical metrology, using high quality test targets: (i) calibration and quality of absorbance measurements and the camera requirements for 3D dosimetry; (ii) the modulation transfer function (MTF) of individual projections; (iii) signal-to-noise ratio (SNR) in the projection and reconstruction domains; (iv) distortion in the projection domain, depth-of-field (DOF) and telecentricity. The principal results for our current apparatus are as follows: (i) SNR of optical absorbance in projections is better than 120:1 for uniform phantoms in absorbance range 0.3 to 1.6 (and better than 200:1 for absorbances 1.0 to 3.5 with the test target and a novel absorbance range extension method), (ii) the spatial resolution is shown to be at worst 0.5 mm (and often better than this) with an associated DOF of 8 cm, (iii) the SNR of uniform phantoms in reconstruction domain is above 80:1 (one standard deviation) over an absorbance dynamic range of 0.3 to 1.6, (iv) the apparatus is telecentric and without distortion. Finally, a sample scan and reconstruction of a scan of a PRESAGE dosimeter are shown, demonstrating the capabilities of the apparatus.
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Affiliation(s)
- Nikola Krstajić
- Department of Physics, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
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Abstract
Optical computed tomography (optical-CT) of 3D radiation dosimeters is a promising avenue for delivering an economic and reliable quality control of radiotherapy treatments such as intensity modulated radiotherapy, brachytherapy and stereotactic radiosurgery. The main problems in transferring 3D dosimeters to clinical setting have been in (1) the complexity of manufacture and behaviour of 3D dosimeters and (2) time-consuming readout and analysis of 3D dosimeters. This paper addresses the readout problem by showing that fast (20 min tomography scan), precise (projection absorbance signal-to-noise ratio is greater than 100:1 across the absorbance range 0.2 to 1.5) and accurate (good linearity in the calibration curve) measurements are possible using a novel method of optically scanning a laser beam across the 3D dosimeter.
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Affiliation(s)
- Nikola Krstajić
- Department of Physics, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
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Doran S, Al-Nowais S, Krstajić N, Adamovics J, Kacperek A, Brunt J. True-3D scans using PRESAGETMand Optical-CT: A case study in proton therapy. ACTA ACUST UNITED AC 2007. [DOI: 10.1088/1742-6596/56/1/036] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Abstract
Optical tomography of gel dosimeters is a promising and cost-effective avenue for quality control of radiotherapy treatments such as intensity-modulated radiotherapy (IMRT). Systems based on a laser coupled to a photodiode have so far shown the best results within the context of optical scanning of radiosensitive gels, but are very slow ( approximately 9 min per slice) and poorly suited to measurements that require many slices. Here, we describe a fast, three-dimensional (3D) optical computed tomography (optical-CT) apparatus, based on a broad, collimated beam, obtained from a high power LED and detected by a charged coupled detector (CCD). The main advantages of such a system are (i) an acquisition speed approximately two orders of magnitude higher than a laser-based system when 3D data are required, and (ii) a greater simplicity of design. This paper advances our previous work by introducing a new design of focusing optics, which take information from a suitably positioned focal plane and project an image onto the CCD. An analysis of the ray optics is presented, which explains the roles of telecentricity, focusing, acceptance angle and depth-of-field (DOF) in the formation of projections. A discussion of the approximation involved in measuring the line integrals required for filtered backprojection reconstruction is given. Experimental results demonstrate (i) the effect on projections of changing the position of the focal plane of the apparatus, (ii) how to measure the acceptance angle of the optics, and (iii) the ability of the new scanner to image both absorbing and scattering gel phantoms. The quality of reconstructed images is very promising and suggests that the new apparatus may be useful in a clinical setting for fast and accurate 3D dosimetry.
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Affiliation(s)
- Nikola Krstajić
- Department of Physics, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
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Krstajić N, Popović M, Grgur B, Vojnović M, Šepa D. On the kinetics of the hydrogen evolution reaction on nickel in alkaline solution. J Electroanal Chem (Lausanne) 2001. [DOI: 10.1016/s0022-0728(01)00590-3] [Citation(s) in RCA: 159] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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32
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Krstajić N, Nakić V, Spasojević M. Hypochlorite production II. Direct electrolysis in a cell divided by an anionic membrane. J APPL ELECTROCHEM 1991. [DOI: 10.1007/bf01024853] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Krstajić N, Krstajić V. [Acid-base status in normal pregnancy and in pregnancy with toxicosis]. SRP ARK CELOK LEK 1979; 107:653-6. [PMID: 552157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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36
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Krstajić V, Krstajić N. [Ovarian carcinoma under the guise of acute abdomen]. SRP ARK CELOK LEK 1979; 107:577-9. [PMID: 531680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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37
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Krstajić V, Krstajić N. [Primary multiple malignancy. Case report]. SRP ARK CELOK LEK 1979; 107:501-3. [PMID: 538531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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38
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Krstajić V, Krstajić N. [Cesarean section using the Phanenstiel incision]. SRP ARK CELOK LEK 1979; 107:379-80. [PMID: 531671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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39
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Krstajić V, Krstajić N. [Simultaneous uterine and extrauterine pregnancy]. SRP ARK CELOK LEK 1978; 106:783-4. [PMID: 752959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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40
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Krstajić V, Krstajić N, Cvetković S. [Surgical treatment of habitual abortion]. SRP ARK CELOK LEK 1976; 104:527-9. [PMID: 1025768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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