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Fang Q, Tomar A, Dunn AK. Wide-field intensity fluctuation imaging. BIOMEDICAL OPTICS EXPRESS 2024; 15:1004-1020. [PMID: 38404351 PMCID: PMC10890890 DOI: 10.1364/boe.506870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 01/08/2024] [Accepted: 01/09/2024] [Indexed: 02/27/2024]
Abstract
The temporal intensity fluctuations contain important information about the light source and light-medium interaction and are typically characterized by the intensity autocorrelation function, g2(τ). The measurement of g2(τ) is a central topic in many optical sensing applications, ranging from stellar intensity interferometer in astrophysics, to fluorescence correlation spectroscopy in biomedical sciences and blood flow measurement with dynamic light scattering. Currently, g2(τ) at a single point is readily accessible through high-frequency sampling of the intensity signal. However, two-dimensional wide-field imaging of g2(τ) is still limited by the cameras' frame rate. We propose and demonstrate a 2-pulse within-exposure modulation approach to break through the camera frame rate limit and obtain the quasi g2(τ) map in wide field with cameras of only ordinary frame rates.
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Affiliation(s)
- Qingwei Fang
- Department of Biomedical Engineering, The University of Texas at Austin , Austin, Texas 78712, USA
| | - Alankrit Tomar
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Andrew K Dunn
- Department of Biomedical Engineering, The University of Texas at Austin , Austin, Texas 78712, USA
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, USA
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2
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Kashchenko VA, Lodygin AV, Krasnoselsky KY, Zaytsev VV, Kamshilin AA. Intra-abdominal laparoscopic assessment of organs perfusion using imaging photoplethysmography. Surg Endosc 2023; 37:8919-8929. [PMID: 37872427 DOI: 10.1007/s00464-023-10506-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 09/23/2023] [Indexed: 10/25/2023]
Abstract
BACKGROUND An objective evaluation of the functional state and viability of biological tissues during minimally invasive surgery remains unsolved task. Various non-contact methods for evaluating perfusion during laparoscopic surgery are discussed in the literature, but so far there have been no reports of their use in clinical settings. METHODS AND PATIENTS Imaging photoplethysmography (iPPG) is a new method for quantitative assessment of perfusion distribution along the tissue. This is the first study in which we demonstrate successful use of iPPG to assess perfusion of organs during laparoscopic surgery in an operation theater. We used a standard rigid laparoscope connected to a standard digital monochrome camera, and abdominal organs were illuminated by green light. A distinctive feature is the synchronous recording of video frames and electrocardiogram with subsequent correlation data processing. During the laparoscopically assisted surgeries in nine cancer patients, the gradient of perfusion of the affected organs was evaluated. In particular, measurements were carried out before preparing a part of the intestine or stomach for resection, after anastomosis, or during physiological tests. RESULTS The spatial distribution of perfusion and its changes over time were successfully measured in all surgical cases. In particular, perfusion gradient of an intestine before resection was visualized and quantified by our iPPG laparoscope in all respective cases. It was also demonstrated that systemic administration of norepinephrine leads to a sharper gradient between well and poorly perfused areas of the colon. In four surgical cases, we have shown capability of the laparoscopic iPPG system for intra-abdominal assessment of perfusion in the anastomosed organs. Moreover, good repeatability of continuous long-term measurements of tissue perfusion inside the abdominal cavity was experimentally demonstrated. CONCLUSION Our study carried out in real clinical settings has shown that iPPG laparoscope is feasible for intra-abdominal visualization and quantitative assessment of perfusion distribution.
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Affiliation(s)
- Victor A Kashchenko
- First Surgical Department, North-Western District Scientific and Clinical Center Named After L.G. Sokolov of the Federal Medical and Biological Agency, Saint Petersburg, Russia, 194291
- Department of Faculty Surgery, St. Petersburg State University, Saint Petersburg, Russia, 199106
| | - Alexander V Lodygin
- First Surgical Department, North-Western District Scientific and Clinical Center Named After L.G. Sokolov of the Federal Medical and Biological Agency, Saint Petersburg, Russia, 194291
- Department of Faculty Surgery, St. Petersburg State University, Saint Petersburg, Russia, 199106
| | - Konstantin Yu Krasnoselsky
- First Surgical Department, North-Western District Scientific and Clinical Center Named After L.G. Sokolov of the Federal Medical and Biological Agency, Saint Petersburg, Russia, 194291
- Department of Anesthesiology-Resuscitation and Emergency Pediatrics, St. Petersburg State Pediatric Medical University, Saint Petersburg, Russia, 194100
| | - Valeriy V Zaytsev
- Laboratory of New Functional Materials for Photonics, Institute of Automation and Control Processes of the Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia, 690041
- Organizational and Methodological Department, North-Western District Scientific and Clinical Center Named After L.G. Sokolov of the Federal Medical and Biological Agency, Saint Petersburg, Russia, 194291
| | - Alexei A Kamshilin
- Laboratory of New Functional Materials for Photonics, Institute of Automation and Control Processes of the Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia, 690041.
- Organizational and Methodological Department, North-Western District Scientific and Clinical Center Named After L.G. Sokolov of the Federal Medical and Biological Agency, Saint Petersburg, Russia, 194291.
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Phan T, Crouzet C, Kennedy GT, Durkin AJ, Choi B. Quantitative hemodynamic imaging: a method to correct the effects of optical properties on laser speckle imaging. NEUROPHOTONICS 2023; 10:045001. [PMID: 37795105 PMCID: PMC10546199 DOI: 10.1117/1.nph.10.4.045001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 08/22/2023] [Accepted: 09/12/2023] [Indexed: 10/06/2023]
Abstract
Significance Studying cerebral hemodynamics may provide diagnostic information on neurological conditions. Wide-field imaging techniques, such as laser speckle imaging (LSI) and optical intrinsic signal imaging, are commonly used to study cerebral hemodynamics. However, they often do not account appropriately for the optical properties of the brain that can vary among subjects and even during a single measurement. Here, we describe the combination of LSI and spatial-frequency domain imaging (SFDI) into a wide-field quantitative hemodynamic imaging (QHI) system that can correct the effects of optical properties on LSI measurements to achieve a quantitative measurement of cerebral blood flow (CBF). Aim We describe the design, fabrication, and testing of QHI. Approach The QHI hardware combines LSI and SFDI with spatial and temporal synchronization. We characterized system sensitivity, accuracy, and precision with tissue-mimicking phantoms. With SFDI optical property measurements, we describe a method derived from dynamic light scattering to obtain absolute CBF values from LSI and SFDI measurements. We illustrate the potential benefits of absolute CBF measurements in resting-state and dynamic experiments. Results QHI achieved a 50-Hz raw acquisition frame rate with a 10 × 10 mm field of view and flow sensitivity up to ∼ 4 mm / s . The extracted SFDI optical properties agreed well with a commercial system (R 2 ≥ 0.98 ). The system showed high stability with low coefficients of variations over multiple sessions within the same day (< 1 % ) and over multiple days (< 4 % ). When optical properties were considered, the in-vivo hypercapnia gas challenge showed a slight difference in CBF (- 1.5 % to 0.5% difference). The in-vivo resting-state experiment showed a change in CBF ranking for nine out of 13 animals when the correction method was applied to LSI CBF measurements. Conclusions We developed a wide-field QHI system to account for the confounding effects of optical properties on CBF LSI measurements using the information obtained from SFDI.
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Affiliation(s)
- Thinh Phan
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, Irvine, California, United States
- University of California, Irvine, Department of Biomedical Engineering, Irvine, California, United States
| | - Christian Crouzet
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, Irvine, California, United States
| | - Gordon T. Kennedy
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, Irvine, California, United States
| | - Anthony J. Durkin
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, Irvine, California, United States
- University of California, Irvine, Department of Biomedical Engineering, Irvine, California, United States
| | - Bernard Choi
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, Irvine, California, United States
- University of California, Irvine, Department of Biomedical Engineering, Irvine, California, United States
- University of California, Irvine, Department of Surgery, Irvine, California, United States
- University of California, Irvine, Edwards Lifesciences Cardiovascular Innovation Research Center, Irvine, California, United States
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4
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Yu CY, Chammas M, Gurden H, Lin HH, Pain F. Design and validation of a convolutional neural network for fast, model-free blood flow imaging with multiple exposure speckle imaging. BIOMEDICAL OPTICS EXPRESS 2023; 14:4439-4454. [PMID: 37791260 PMCID: PMC10545206 DOI: 10.1364/boe.492739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/15/2023] [Accepted: 07/10/2023] [Indexed: 10/05/2023]
Abstract
Multiple exposure speckle imaging has demonstrated its improved accuracy compared to single exposure speckle imaging for relative quantitation of blood flow in vivo. However, the calculation of blood flow maps relies on a pixelwise non-linear fit of a multi-parametric model to the speckle contrasts. This approach has two major drawbacks. First, it is computer-intensive and prevents real time imaging and, second, the mathematical model is not universal and should in principle be adapted to the type of blood vessels. We evaluated a model-free machine learning approach based on a convolutional neural network as an alternative to the non-linear fit approach. A network was designed and trained with annotated speckle contrast data from microfluidic experiments. The neural network performances are then compared to the non-linear fit approach applied to in vitro and in vivo data. The study demonstrates the potential of convolutional networks to provide relative blood flow maps from multiple exposure speckle data in real time.
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Affiliation(s)
- Chao-Yueh Yu
- Chang-Gung University, Department of Medical Imaging and Radiological Sciences, Taoyuan City, Taiwan
| | - Marc Chammas
- Université Paris-Saclay, Institut d'Optique Graduate School, CNRS, Laboratoire Charles Fabry, 91127, Palaiseau, France
| | - Hirac Gurden
- Université Paris Cité, CNRS, Laboratoire Biologie Fonctionnelle et Adaptative, 75013, Paris, France
| | - Hsin-Hon Lin
- Chang-Gung University, Department of Medical Imaging and Radiological Sciences, Taoyuan City, Taiwan
- Department of Nuclear Medicine, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Frédéric Pain
- Université Paris-Saclay, Institut d'Optique Graduate School, CNRS, Laboratoire Charles Fabry, 91127, Palaiseau, France
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Fang Q, Tomar A, Dunn AK. Wide-field Intensity Fluctuation Imaging. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.29.551117. [PMID: 37546910 PMCID: PMC10402166 DOI: 10.1101/2023.07.29.551117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
The temporal intensity fluctuations contain important information about the light source and light-medium interaction and are typically characterized by the intensity autocorrelation function, g 2 ( τ ) . The measurement of g 2 ( τ ) is a central topic in many optical sensing applications, ranging from stellar intensity interferometer in astrophysics, to fluorescence correlation spectroscopy in biomedical sciences and blood flow measurement with dynamic light scattering. Currently, g 2 ( τ ) at a single point is readily accessible through high-frequency sampling of the intensity signal. However, two-dimensional wide-field measurement of g 2 ( τ ) is still limited by camera frame rates. We propose and demonstrate a 2-pulse within-exposure modulation approach to break through the camera frame rate limit and obtain the quasi g 2 ( τ ) map in wide field with cameras of only ordinary frame rates.
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Affiliation(s)
- Qingwei Fang
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, 78712, TX, US
| | - Alankrit Tomar
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, 78712, TX, US
| | - Andrew K. Dunn
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, 78712, TX, US
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, 78712, TX, US
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6
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Meng L, Huang M, Feng S, Wang Y, Lu J, Li P. Optical Flow-Based Full-Field Quantitative Blood-Flow Velocimetry Using Temporal Direction Filtering and Peak Interpolation. Int J Mol Sci 2023; 24:12048. [PMID: 37569421 PMCID: PMC10419297 DOI: 10.3390/ijms241512048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 07/15/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
The quantitative measurement of the microvascular blood-flow velocity is critical to the early diagnosis of microvascular dysfunction, yet there are several challenges with the current quantitative flow velocity imaging techniques for the microvasculature. Optical flow analysis allows for the quantitative imaging of the blood-flow velocity with a high spatial resolution, using the variation in pixel brightness between consecutive frames to trace the motion of red blood cells. However, the traditional optical flow algorithm usually suffers from strong noise from the background tissue, and a significant underestimation of the blood-flow speed in blood vessels, due to the errors in detecting the feature points in optical images. Here, we propose a temporal direction filtering and peak interpolation optical flow method (TPIOF) to suppress the background noise, and improve the accuracy of the blood-flow velocity estimation. In vitro phantom experiments and in vivo animal experiments were performed to validate the improvements in our new method.
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Affiliation(s)
- Liangwei Meng
- Britton Chance Center for Biomedical Photonics and MoE Key Laboratory for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China; (L.M.); (M.H.); (Y.W.); (J.L.)
- Research Unit of Multimodal Cross Scale Neural Signal Detection and Imaging, Chinese Academy of Medical Science, HUST-Suzhou Institute for Brainsmatics, Jiangsu Industrial Technology Reserch Institute (JITRI), Suzhou 215100, China
| | - Mange Huang
- Britton Chance Center for Biomedical Photonics and MoE Key Laboratory for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China; (L.M.); (M.H.); (Y.W.); (J.L.)
- Research Unit of Multimodal Cross Scale Neural Signal Detection and Imaging, Chinese Academy of Medical Science, HUST-Suzhou Institute for Brainsmatics, Jiangsu Industrial Technology Reserch Institute (JITRI), Suzhou 215100, China
| | - Shijie Feng
- Britton Chance Center for Biomedical Photonics and MoE Key Laboratory for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China; (L.M.); (M.H.); (Y.W.); (J.L.)
- Research Unit of Multimodal Cross Scale Neural Signal Detection and Imaging, Chinese Academy of Medical Science, HUST-Suzhou Institute for Brainsmatics, Jiangsu Industrial Technology Reserch Institute (JITRI), Suzhou 215100, China
| | - Yiqian Wang
- Britton Chance Center for Biomedical Photonics and MoE Key Laboratory for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China; (L.M.); (M.H.); (Y.W.); (J.L.)
- Research Unit of Multimodal Cross Scale Neural Signal Detection and Imaging, Chinese Academy of Medical Science, HUST-Suzhou Institute for Brainsmatics, Jiangsu Industrial Technology Reserch Institute (JITRI), Suzhou 215100, China
| | - Jinling Lu
- Britton Chance Center for Biomedical Photonics and MoE Key Laboratory for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China; (L.M.); (M.H.); (Y.W.); (J.L.)
- Research Unit of Multimodal Cross Scale Neural Signal Detection and Imaging, Chinese Academy of Medical Science, HUST-Suzhou Institute for Brainsmatics, Jiangsu Industrial Technology Reserch Institute (JITRI), Suzhou 215100, China
| | - Pengcheng Li
- Britton Chance Center for Biomedical Photonics and MoE Key Laboratory for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China; (L.M.); (M.H.); (Y.W.); (J.L.)
- Research Unit of Multimodal Cross Scale Neural Signal Detection and Imaging, Chinese Academy of Medical Science, HUST-Suzhou Institute for Brainsmatics, Jiangsu Industrial Technology Reserch Institute (JITRI), Suzhou 215100, China
- Department of Biomedical Engineering, Hainan University, Haikou 570228, China
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Chizari A, Tsong W, Knop T, Steenbergen W. Prediction of motion artifacts caused by translation in handheld laser speckle contrast imaging. JOURNAL OF BIOMEDICAL OPTICS 2023; 28:046005. [PMID: 37082096 PMCID: PMC10112282 DOI: 10.1117/1.jbo.28.4.046005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 03/24/2023] [Indexed: 05/03/2023]
Abstract
Significance In handheld laser speckle contrast imaging (LSCI), motion artifacts (MA) are inevitable. Suppression of MA leads to a valid and objective assessment of tissue perfusion in a wide range of medical applications including dermatology and burns. Our study shines light on the sources of these artifacts, which have not yet been explored. We propose a model based on optical Doppler effect to predict speckle contrast drop as an indication of MA. Aim We aim to theoretically model MA when an LSCI system measuring on static scattering media is subject to translational displacements. We validate the model using both simulation and experiments. This is the crucial first step toward creating robustness against MA. Approach Our model calculates optical Doppler shifts in order to predict intensity correlation function and contrast of the time-integrated intensity as functions of applied speed based on illumination and detection wavevectors. To validate the theoretical predictions, computer simulation of the dynamic speckles has been carried out. Then experiments are performed by both high-speed and low-framerate imaging. The employed samples for the experiments are a highly scattering matte surface and a Delrin plate of finite scattering level in which volume scattering occurs. Results An agreement has been found between theoretical prediction, simulation, and experimental results of both intensity correlation functions and speckle contrast. Coefficients in the proposed model have been linked to the physical parameters according to the experimental setups. Conclusions The proposed model provides a quantitative description of the influence of the types of illumination and media in the creation of MA. The accurate prediction of MA caused by translation based on Doppler shifts makes our model suitable to study the influence of rotation. Also the model can be extended for the case of dynamic media, such as live tissue.
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Affiliation(s)
- Ata Chizari
- University of Twente, Technical Medical Centre, Faculty of Science and Technology, Biomedical Photonic Imaging Group, Enschede, The Netherlands
- Address all correspondence to Ata Chizari,
| | - Wilson Tsong
- University of Twente, Technical Medical Centre, Faculty of Science and Technology, Biomedical Photonic Imaging Group, Enschede, The Netherlands
| | - Tom Knop
- University of Twente, Technical Medical Centre, Faculty of Science and Technology, Biomedical Photonic Imaging Group, Enschede, The Netherlands
| | - Wiendelt Steenbergen
- University of Twente, Technical Medical Centre, Faculty of Science and Technology, Biomedical Photonic Imaging Group, Enschede, The Netherlands
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8
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Hultman M, Larsson M, Strömberg T, Fredriksson I. Speed-resolved perfusion imaging using multi-exposure laser speckle contrast imaging and machine learning. JOURNAL OF BIOMEDICAL OPTICS 2023; 28:036007. [PMID: 36950019 PMCID: PMC10027009 DOI: 10.1117/1.jbo.28.3.036007] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 02/27/2023] [Indexed: 05/19/2023]
Abstract
SIGNIFICANCE Laser speckle contrast imaging (LSCI) gives a relative measure of microcirculatory perfusion. However, due to the limited information in single-exposure LSCI, models are inaccurate for skin tissue due to complex effects from e.g. static and dynamic scatterers, multiple Doppler shifts, and the speed-distribution of blood. It has been demonstrated how to account for these effects in laser Doppler flowmetry (LDF) using inverse Monte Carlo (MC) algorithms. This allows for a speed-resolved perfusion measure in absolute units %RBC × mm/s, improving the physiological interpretation of the data. Until now, this has been limited to a single-point LDF technique but recent advances in multi-exposure LSCI (MELSCI) enable the analysis in an imaging modality. AIM To present a method for speed-resolved perfusion imaging in absolute units %RBC × mm/s, computed from multi-exposure speckle contrast images. APPROACH An artificial neural network (ANN) was trained on a large simulated dataset of multi-exposure contrast values and corresponding speed-resolved perfusion. The dataset was generated using MC simulations of photon transport in randomized skin models covering a wide range of physiologically relevant geometrical and optical tissue properties. The ANN was evaluated on in vivo data sets captured during an occlusion provocation. RESULTS Speed-resolved perfusion was estimated in the three speed intervals 0 to 1 mm / s , 1 to 10 mm / s , and > 10 mm / s , with relative errors 9.8%, 12%, and 19%, respectively. The perfusion had a linear response to changes in both blood tissue fraction and blood flow speed and was less affected by tissue properties compared with single-exposure LSCI. The image quality was subjectively higher compared with LSCI, revealing previously unseen macro- and microvascular structures. CONCLUSIONS The ANN, trained on modeled data, calculates speed-resolved perfusion in absolute units from multi-exposure speckle contrast. This method facilitates the physiological interpretation of measurements using MELSCI and may increase the clinical impact of the technique.
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Affiliation(s)
- Martin Hultman
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
- Perimed AB, Stockholm, Sweden
- Address all correspondence to Martin Hultman,
| | - Marcus Larsson
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
| | - Tomas Strömberg
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
| | - Ingemar Fredriksson
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
- Perimed AB, Stockholm, Sweden
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Santorelli A, Sullender CT, Dunn AK. Multi-exposure Speckle Imaging for Quantitative Evaluation of Cortical Blood Flow. Methods Mol Biol 2023; 2616:97-111. [PMID: 36715931 DOI: 10.1007/978-1-0716-2926-0_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Laser speckle contrast imaging (LSCI) is a label-free optical imaging technique that can quantify flow dynamics across an entire image. Multi-exposure speckle imaging (MESI) is an extension of LSCI that allows for reproducible and quantifiable measurements of flow. MESI has the potential to provide quantitative cerebral blood flow information in both preclinical and clinical applications; in fact, MESI can be extended to resolve the flow dynamics in any exposed tissue. A MESI system can be divided into three primary components: (i) the illumination optics, consisting of the optical source and a method of modulating and gating the illumination intensity; (ii) the collection optics, consisting of a high-speed camera that can be triggered and gated to match the pulsed illumination; and finally (iii) post-processing hardware and software to extract the flow information from the recorded raw intensity images. In the following protocol, we offer a guide to design, operate, and test a MESI system.
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Affiliation(s)
- Adam Santorelli
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA.
| | - Colin T Sullender
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Andrew K Dunn
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
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10
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Smith C, Santorelli A, Engelmann S, Dunn AK. All fiber-based illumination system for multi-exposure speckle imaging. BIOMEDICAL OPTICS EXPRESS 2023; 14:771-782. [PMID: 36874493 PMCID: PMC9979660 DOI: 10.1364/boe.476178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 12/15/2022] [Accepted: 12/29/2022] [Indexed: 06/18/2023]
Abstract
Monitoring blood flow is critical to treatment efficacy in many surgical settings. Laser speckle contrast imaging (LSCI) is a simple, real-time, label-free optical technique for monitoring blood flow that has emerged as a promising technique but lacks the ability to make repeatable quantitative measurements. Multi-exposure speckle imaging (MESI) is an extension of LSCI that requires increased complexity of instrumentation, which has limited its adoption. In this paper, we design and fabricate a compact, fiber-coupled MESI illumination system (FCMESI) that is substantially smaller and less complex than previous systems. Using microfluidics flow phantoms, we demonstrate that the FCMESI system measures flow with an accuracy and repeatability equivalent to traditional free space MESI illumination systems. With an in vivo stroke model, we also demonstrate the ability of FCMESI to monitor cerebral blood flow changes.
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11
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Chong SH, Ong YH, El Khatib M, Allu SR, Parthasarathy AB, Greenberg JH, Yodh AG, Vinogradov SA. Real-time tracking of brain oxygen gradients and blood flow during functional activation. NEUROPHOTONICS 2022; 9:045006. [PMID: 36457848 PMCID: PMC9704417 DOI: 10.1117/1.nph.9.4.045006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Accepted: 11/01/2022] [Indexed: 06/11/2023]
Abstract
Significance Cerebral metabolic rate of oxygen ( CMRO 2 ) consumption is a key physiological variable that characterizes brain metabolism in a steady state and during functional activation. Aim We aim to develop a minimally invasive optical technique for real-time measurement of CMRO 2 concurrently with cerebral blood flow (CBF). Approach We used a pair of macromolecular phosphorescent probes with nonoverlapping optical spectra, which were localized in the intra- and extravascular compartments of the brain tissue, thus providing a readout of oxygen gradients between these two compartments. In parallel, we measured CBF using laser speckle contrast imaging. Results The method enables computation and tracking of CMRO 2 during functional activation with high temporal resolution ( ∼ 7 Hz ). In contrast to other approaches, our assessment of CMRO 2 does not require measurements of CBF or hemoglobin oxygen saturation. Conclusions The independent records of intravascular and extravascular partial pressures of oxygen, CBF, and CMRO 2 provide information about the physiological events that accompany neuronal activation, creating opportunities for dynamic quantification of brain metabolism.
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Affiliation(s)
- Sang Hoon Chong
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania, United States
| | - Yi Hong Ong
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, Department of Radiation Oncology, Philadelphia, Pennsylvania, United States
| | - Mirna El Khatib
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
| | - Srinivasa Rao Allu
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
| | - Ashwin B. Parthasarathy
- University of South Florida, Department of Electrical Engineering, Tampa, Florida, United States
| | - Joel H. Greenberg
- University of Pennsylvania, Department of Neurology, Philadelphia, Pennsylvania, United States
| | - Arjun G. Yodh
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania, United States
| | - Sergei A. Vinogradov
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
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12
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Miller DR, Ashour R, Sullender CT, Dunn AK. Continuous blood flow visualization with laser speckle contrast imaging during neurovascular surgery. NEUROPHOTONICS 2022; 9:021908. [PMID: 35265733 PMCID: PMC8900813 DOI: 10.1117/1.nph.9.2.021908] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 02/11/2022] [Indexed: 06/14/2023]
Abstract
Significance: Laser speckle contrast imaging (LSCI) has emerged as a promising tool for intraoperative cerebral blood flow (CBF) monitoring because it produces real-time full-field blood flow maps noninvasively and label free. Aim: We aim to demonstrate the ability of LSCI to continuously visualize blood flow during neurovascular procedures. Approach: LSCI hardware was attached to the surgical microscope and did not interfere with the normal operation of the microscope. To more easily visualize CBF in real time, LSCI images were registered with the built-in microscope white light camera such that LSCI images were overlaid on the white light images and displayed to the neurosurgeon continuously in real time. Results: LSCI was performed throughout each surgery when the microscope was positioned over the patient, providing the surgeon with real-time visualization of blood flow changes before, during, and after aneurysm clipping or arteriovenous malformation (AVM) resection in humans. LSCI was also compared with indocyanine green angiography (ICGA) to assess CBF during aneurysm clipping and AVM surgery; integration of the LSCI hardware with the microscope enabled simultaneous acquisition of LSCI and ICGA. Conclusions: The results suggest that LSCI can provide continuous and real-time CBF visualization without affecting the surgeon workflow or requiring a contrast agent. The results also demonstrate that LSCI and ICGA provide different, yet complementary information about vessel perfusion.
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Affiliation(s)
- David R. Miller
- The University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Ramsey Ashour
- The University of Texas at Austin, Dell Medical School, Department of Neurosurgery, Austin, Texas, United States
| | - Colin T. Sullender
- The University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Andrew K. Dunn
- The University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
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13
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Imaging photoplethysmography as an easy-to-use tool for monitoring changes in tissue blood perfusion during abdominal surgery. Sci Rep 2022; 12:1143. [PMID: 35064190 PMCID: PMC8782890 DOI: 10.1038/s41598-022-05080-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 01/06/2022] [Indexed: 01/01/2023] Open
Abstract
Evaluation of tissue perfusion at various stages of surgery is of great importance for the implementation of the concept of safe surgery, including operations on the abdominal organs. Currently, there is no accurate and reliable intraoperative method for assessing tissue perfusion that could help surgeons determine the risks of ischemia and improve outcomes. We propose novel method of intraoperative assessment of tissue perfusion using video camera synchronized with the electrocardiogram. The technique is referred to as imaging photoplethysmography (iPPG). It can be used continuously for monitoring blood supply to organs e.g., before and after anastomosis. In our study, we followed 14 different surgical cases (four stomach and ten colorectal cancers) requiring reconstruction of various organs with anastomosis. With iPPG, intraoperative blood perfusion was successfully visualized and quantified in all 14 patients under study. As most indicative, here we describe in detail two clinical demonstrations during gastrectomy for gastric cancer and right-sided hemicolectomy for cancer of the ascending colon. Feasibility of the iPPG system to assess blood perfusion in organs before and after anastomosis during open surgery was demonstrated for the first time.
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14
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Sullender CT, Richards LM, He F, Luan L, Dunn AK. Dynamics of isoflurane-induced vasodilation and blood flow of cerebral vasculature revealed by multi-exposure speckle imaging. J Neurosci Methods 2022; 366:109434. [PMID: 34863840 PMCID: PMC9258779 DOI: 10.1016/j.jneumeth.2021.109434] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 11/12/2021] [Accepted: 11/29/2021] [Indexed: 10/19/2022]
Abstract
BACKGROUND Anesthetized animal models are used extensively during neurophysiological and behavioral studies despite systemic effects from anesthesia that undermine both accurate interpretation and translation to awake human physiology. The majority of work examining the impact of anesthesia on cerebral blood flow (CBF) has been restricted to before and after measurements with limited spatial resolution. NEW METHOD We used multi-exposure speckle imaging (MESI), an advanced form of laser speckle contrast imaging (LSCI), to characterize the dynamics of isoflurane anesthesia induction on cerebral vasculature and blood flow in the mouse brain. RESULTS The large anatomical changes caused by isoflurane are depicted with wide-field imagery and video highlighting the induction of general anesthesia. Within minutes of exposure, both vessel diameter and blood flow increased drastically compared to the awake state and remained elevated for the duration of imaging. An examination of the dynamics of anesthesia induction reveals that blood flow increased faster in arteries than in veins or parenchyma regions. COMPARISON WITH EXISTING METHODS MESI offers robust hemodynamic measurements across large fields-of-view and high temporal resolutions sufficient for continuous visualization of cerebrovascular events featuring major changes in blood flow. CONCLUSION The large alterations caused by isoflurane anesthesia to the cortical vasculature and CBF are readily characterized using MESI. These changes are unrepresentative of normal physiology and provide further evidence that neuroscience experiments would benefit from transitioning to un-anesthetized awake animal models.
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Affiliation(s)
- Colin T Sullender
- Department of Biomedical Engineering, University of Texas at Austin, 107 W. Dean Keeton Street Stop C0800, Austin, TX 78712, United States
| | - Lisa M Richards
- Department of Biomedical Engineering, University of Texas at Austin, 107 W. Dean Keeton Street Stop C0800, Austin, TX 78712, United States
| | - Fei He
- Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, United States
| | - Lan Luan
- Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, United States; Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX 77005, United States
| | - Andrew K Dunn
- Department of Biomedical Engineering, University of Texas at Austin, 107 W. Dean Keeton Street Stop C0800, Austin, TX 78712, United States.
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15
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Yordanov S, Drucker M, Butt HJ, Koynov K. Real-time monitoring of biomechanical activity in aphids by laser speckle contrast imaging. OPTICS EXPRESS 2021; 29:28461-28480. [PMID: 34614977 DOI: 10.1364/oe.431989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 07/20/2021] [Indexed: 06/13/2023]
Abstract
Studying in vivo feeding and other behaviors of small insects, such as aphids, is important for understanding their lifecycle and interaction with the environment. In this regard, the EPG (electrical penetration graph) technique is widely used to study the feeding activity in aphids. However, it is restricted to recording feeding of single insects and requires wiring insects to an electrode, impeding free movement. Hence, easy and straightforward collective observations, e.g. of groups of aphids on a plant, or probing other aphid activities in various body parts, is not possible. To circumvent these drawbacks, we developed a method based on an optical technique called laser speckle contrast imaging (LSCI). It has the potential for direct, non-invasive and contactless monitoring of a broad range of internal and external activities such as feeding, hemolymph cycling and muscle contractions in aphids or other insects. The method uses a camera and coherent light illumination of the sample. The camera records the laser speckle dynamics due to the scattering and interference of light caused by moving scatters in a probed region of the insect. Analyzing the speckle contrast allowed us to monitor and extract the activity information during aphid feeding on leaves or on artificial medium containing tracer particles. We present evidence that the observed speckle dynamics might be caused by muscle contractions, movement of hemocytes in the circulatory system or food flows in the stylets. This is the first time such a remote sensing method has been applied for optical mapping of the biomechanical activities in aphids.
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16
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Soleimanzad H, Montaner M, Ternier G, Lemitre M, Silvestre JS, Kassis N, Giacobini P, Magnan C, Pain F, Gurden H. Obesity in Midlife Hampers Resting and Sensory-Evoked Cerebral Blood Flow in Mice. Obesity (Silver Spring) 2021; 29:150-158. [PMID: 33174382 DOI: 10.1002/oby.23051] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/10/2020] [Accepted: 09/14/2020] [Indexed: 12/16/2022]
Abstract
OBJECTIVE This study aimed to investigate the effects of a high-fat diet (HFD) and aging on resting and activity-dependent cerebral blood flow (CBF). METHODS To run a comparison between obese and age-matched control animals, 6-week-old mice were fed either with regular chow or an HFD for 3 months or 8 months. Glucose tolerance and insulin sensitivity were assessed for metabolic phenotyping. Resting and odor-evoked CBF at the microvascular scale in the olfactory bulb (OB) was investigated by multiexposure speckle imaging. Immunolabeling-enabled imaging of solvent-cleared organs was used to analyze vascular density. The ejection fraction was studied by using cardioechography. Olfactory sensitivity was tested by using a buried-food test. RESULTS Glucose intolerance and compromised odor-evoked CBF were observed in obese mice in the younger group. Prolonged HFD feeding triggered insulin resistance and stronger impairment in activity-dependent CBF. Aging had a specific negative impact on resting CBF. There was no decrease in vascular density in the OB of obese mice, although cardiac function was impaired at both ages. In addition, decreased olfactory sensitivity was observed only in the older, middle-aged obese mice. CONCLUSIONS OB microvasculature in obese mice showed a specific functional feature characterized by impaired sensory-evoked CBF and a specific deleterious effect of aging on resting CBF.
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Affiliation(s)
- Haleh Soleimanzad
- Université de Paris, Unit of Functional and Adaptive Biology (BFA), UMR 8251 CNRS, Paris, France
| | - Mireia Montaner
- Université de Paris, Unit of Functional and Adaptive Biology (BFA), UMR 8251 CNRS, Paris, France
| | - Gaëtan Ternier
- Université de Lille, INSERM, CHU Lille, U1172 - LilNCog - Lille Neuroscience & Cognition, Lille, France
| | - Mathilde Lemitre
- Université de Paris, Paris Cardiovascular Research Center (PARCC), INSERM, Paris, France
| | | | - Nadim Kassis
- Université de Paris, Unit of Functional and Adaptive Biology (BFA), UMR 8251 CNRS, Paris, France
| | - Paolo Giacobini
- Université de Lille, INSERM, CHU Lille, U1172 - LilNCog - Lille Neuroscience & Cognition, Lille, France
| | - Christophe Magnan
- Université de Paris, Unit of Functional and Adaptive Biology (BFA), UMR 8251 CNRS, Paris, France
| | - Frédéric Pain
- Université Paris-Saclay, Institut d'Optique Graduate School, CNRS, Laboratoire Charles Fabry, Palaiseau, France
| | - Hirac Gurden
- Université de Paris, Unit of Functional and Adaptive Biology (BFA), UMR 8251 CNRS, Paris, France
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17
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Mamontov OV, Sokolov AY, Volynsky MA, Osipchuk AV, Zaytsev VV, Romashko RV, Kamshilin AA. Animal model of assessing cerebrovascular functional reserve by imaging photoplethysmography. Sci Rep 2020; 10:19008. [PMID: 33149189 PMCID: PMC7642404 DOI: 10.1038/s41598-020-75824-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 10/16/2020] [Indexed: 01/12/2023] Open
Abstract
Assessment of the cerebral blood-flow-reserve in patients with cerebrovascular diseases is extremely important in terms of making prognosis, determining treatment tactics, and controlling the revascularization outcome in the case of reconstructive interventions on the brain vessels. However, there is no easy-to-use, contactless method for either assessing the functional reserve of the cortical vascular network or intraoperative monitoring of surgical intervention. Our study aims to demonstrate feasibility of green-light imaging photoplethysmography (iPPG) to estimate cerebrovascular functional reserve in animal model of craniosurgical intervention. Custom-made iPPG system was exploited to visualize intracranial vessels in anesthetized Wistar rats (n = 15). Video frames of rat's cortex were recorded concurrently with systemic blood pressure, end-tidal CO2, and electrocardiogram. We found that injection of dorzolamide (carbonic-anhydrase inhibitor) significantly increased the blood-pulsations amplitude in all animals by 35 ± 19% (p < 0.001). Such an increase negatively correlated with significant decrease in end-tidal CO2 by 32 ± 7% (p < 0.001). It is noteworthy that the dorzolamide injection did not lead to significant changes in systemic blood pressure. Concluding, pulsations amplitude is a marker of the vascular tone that can be used to evaluate the functional cerebrovascular reserve. Imaging PPG is a simple and convenient method to assess cerebral blood flow, including during various neurosurgical interventions.
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Affiliation(s)
- Oleg V Mamontov
- Department of Circulation Physiology, Almazov National Medical Research Centre, Saint Petersburg, Russia.,Department of Departmental Therapy, Pavlov First Saint Petersburg State Medical University, Saint Petersburg, Russia
| | - Alexey Y Sokolov
- Department of Neuropharmacology, Valdman Institute of Pharmacology, Pavlov First Saint Petersburg State Medical University, Saint Petersburg, Russia.,Pavlov Institute of Physiology of the Russian Academy of Sciences, Saint Petersburg, Russia
| | - Maxim A Volynsky
- Faculty of Applied Optics, ITMO University, Saint Petersburg, Russia
| | - Anastasija V Osipchuk
- Department of Neuropharmacology, Valdman Institute of Pharmacology, Pavlov First Saint Petersburg State Medical University, Saint Petersburg, Russia
| | - Valery V Zaytsev
- Faculty of Applied Optics, ITMO University, Saint Petersburg, Russia
| | - Roman V Romashko
- Laboratory of High-Precision Optical Measurements, Institute of Automation and Control Processes FEB RAS, Vladivostok, Russia
| | - Alexei A Kamshilin
- Laboratory of High-Precision Optical Measurements, Institute of Automation and Control Processes FEB RAS, Vladivostok, Russia. .,Faculty of Photonics and Optical Information, ITMO University, Saint Petersburg, Russia.
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18
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Hultman M, Larsson M, Strömberg T, Fredriksson I. Real-time video-rate perfusion imaging using multi-exposure laser speckle contrast imaging and machine learning. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:JBO-200207R. [PMID: 33191685 PMCID: PMC7666876 DOI: 10.1117/1.jbo.25.11.116007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 10/21/2020] [Indexed: 05/03/2023]
Abstract
SIGNIFICANCE Multi-exposure laser speckle contrast imaging (MELSCI) estimates microcirculatory blood perfusion more accurately than single-exposure LSCI. However, the technique has been hampered by technical limitations due to massive data throughput requirements and nonlinear inverse search algorithms, limiting it to an offline technique where data must be postprocessed. AIM To present an MELSCI system capable of continuous acquisition and processing of MELSCI data, enabling real-time video-rate perfusion imaging with high accuracy. APPROACH The MELSCI algorithm was implemented in programmable hardware (field programmable gate array) closely interfaced to a high-speed CMOS sensor for real-time calculation. Perfusion images were estimated in real-time from the MELSCI data using an artificial neural network trained on simulated data. The MELSCI perfusion was compared to two existing single-exposure metrics both quantitatively in a controlled phantom experiment and qualitatively in vivo. RESULTS The MELSCI perfusion shows higher signal dynamics compared to both single-exposure metrics, both spatially and temporally where heartbeat-related variations are resolved in much greater detail. The MELSCI perfusion is less susceptible to measurement noise and is more linear with respect to laser Doppler perfusion in the phantom experiment (R2 = 0.992). CONCLUSIONS The presented MELSCI system allows for real-time acquisition and calculation of high-quality perfusion at 15.6 frames per second.
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Affiliation(s)
- Martin Hultman
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
- Address all correspondence to Martin Hultman,
| | - Marcus Larsson
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
| | - Tomas Strömberg
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
| | - Ingemar Fredriksson
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
- Perimed AB, Järfälla, Stockholm, Sweden
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19
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Jafari CZ, Sullender CT, Miller DR, Mihelic SA, Dunn AK. Effect of vascular structure on laser speckle contrast imaging. BIOMEDICAL OPTICS EXPRESS 2020; 11:5826-5841. [PMID: 33149989 PMCID: PMC7587253 DOI: 10.1364/boe.401235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 08/31/2020] [Accepted: 09/08/2020] [Indexed: 06/11/2023]
Abstract
Laser speckle contrast imaging (LSCI) is a powerful tool for non-invasive, real-time imaging of blood flow in tissue. However, the effect of tissue geometry on the form of the electric field autocorrelation function and speckle contrast values is yet to be investigated. In this paper, we present an ultrafast forward model for simulating a speckle contrast image with the ability to rapidly update the image for a desired illumination pattern and flow perturbation. We demonstrate the first simulated speckle contrast image and compare it against experimental results. We simulate three mouse-specific cerebral cortex decorrelation time images and implement three different schemes for analyzing the effects of homogenization of vascular structure on correlation decay times. Our results indicate that dissolving structure and assuming homogeneous geometry creates up to ∼ 10x shift in the correlation function decay times and alters its form compared with the case for which the exact geometry is simulated. These effects are more pronounced for point illumination and detection imaging schemes, highlighting the significance of accurate modeling of the three-dimensional vascular geometry for accurate blood flow estimates.
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Affiliation(s)
- Chakameh Z. Jafari
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Colin T. Sullender
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA
| | - David R. Miller
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Samuel A. Mihelic
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Andrew K. Dunn
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA
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20
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Intraoperative Imaging of Cortical Blood Flow by Camera-Based Photoplethysmography at Green Light. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10186192] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Intraoperative evaluation of blood perfusion in the brain cortex is an important but hitherto unresolved problem. Our aim was to demonstrate the feasibility of cerebral microcirculation assessment during open brain surgery by using camera-based photoplethysmography (cbPPG) synchronized with an electrocardiograph. Cortical blood flow was monitored in five patients with different diagnoses. Two cases (tumor resection and extra-intracranial bypass grafting) are presented in detail. Blood-flow parameters were visualized after processing cortex images recorded under green-light illumination before and after surgical intervention. In all cases, blood flow was successfully visualized in >95% of open brain. Distributions of blood pulsation amplitude, a parameter related to cortical blood perfusion; pulse arrival time; and blood-pressure-pulse shape were calculated with high spatial resolution (in every pixel). Changes in cerebral blood supply caused by surgical intervention were clearly revealed. We have shown that the temporal spread of pulse arrival time and the spatiotemporal variability of pulse shape are very sensitive markers of brain circulatory disturbances. The green-light cbPPG system offers a new approach to objective assessment of blood-flow changes in the brain during surgical intervention. The proposed system allows for contactless monitoring of cortex blood flow in real time with high resolution, thus providing useful information for surgery optimization and minimization of brain tissue damage.
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21
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He F, Sullender CT, Zhu H, Williamson MR, Li X, Zhao Z, Jones TA, Xie C, Dunn AK, Luan L. Multimodal mapping of neural activity and cerebral blood flow reveals long-lasting neurovascular dissociations after small-scale strokes. SCIENCE ADVANCES 2020; 6:eaba1933. [PMID: 32494746 PMCID: PMC7244270 DOI: 10.1126/sciadv.aba1933] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 03/10/2020] [Indexed: 06/02/2023]
Abstract
Neurovascular coupling, the close spatial and temporal relationship between neural activity and hemodynamics, is disrupted in pathological brain states. To understand the altered neurovascular relationship in brain disorders, longitudinal, simultaneous mapping of neural activity and hemodynamics is critical yet challenging to achieve. Here, we use a multimodal neural platform in a mouse model of stroke and realize long-term, spatially resolved tracking of intracortical neural activity and cerebral blood flow in the same brain regions. We observe a pronounced neurovascular dissociation that occurs immediately after small-scale strokes, becomes the most severe a few days after, lasts into chronic periods, and varies with the level of ischemia. Neuronal deficits extend spatiotemporally, whereas restoration of cerebral blood flow occurs sooner and reaches a higher relative value. Our findings reveal the neurovascular impact of ministrokes and inform the limitation of neuroimaging techniques that infer neural activity from hemodynamic responses.
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Affiliation(s)
- Fei He
- Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA
- Neuroengineering Initiative, Rice University, 6500 Main Street, Houston, TX 77005, USA
| | - Colin T. Sullender
- Department of Biomedical Engineering, The University of Texas at Austin, 107 E. Dean Keeton Street, 1 University Station, C0800, Austin, TX 78712, USA
| | - Hanlin Zhu
- Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA
| | - Michael R. Williamson
- Institute for Neuroscience, The University of Texas at Austin, 1 University Station, Stop C7000, Austin, TX 78712, USA
| | - Xue Li
- Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA
| | - Zhengtuo Zhao
- Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA
- Neuroengineering Initiative, Rice University, 6500 Main Street, Houston, TX 77005, USA
| | - Theresa A. Jones
- Department of Psychology, The University of Texas at Austin, 108 E. Dean Keeton Street, Stop A8000, SEA 6.106, Austin, TX 78712, USA
| | - Chong Xie
- Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA
- Neuroengineering Initiative, Rice University, 6500 Main Street, Houston, TX 77005, USA
- Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX 77005, USA
| | - Andrew K. Dunn
- Department of Biomedical Engineering, The University of Texas at Austin, 107 E. Dean Keeton Street, 1 University Station, C0800, Austin, TX 78712, USA
| | - Lan Luan
- Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA
- Neuroengineering Initiative, Rice University, 6500 Main Street, Houston, TX 77005, USA
- Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX 77005, USA
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22
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Du Le VN, Srinivasan VJ. Beyond diffuse correlations: deciphering random flow in time-of-flight resolved light dynamics. OPTICS EXPRESS 2020; 28:11191-11214. [PMID: 32403635 PMCID: PMC7340374 DOI: 10.1364/oe.385202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Diffusing wave spectroscopy (DWS) and diffuse correlation spectroscopy (DCS) can assess blood flow index (BFI) of biological tissue with multiply scattered light. Though the main biological function of red blood cells (RBCs) is advection, in DWS/DCS, RBCs are assumed to undergo Brownian motion. To explain this discrepancy, we critically examine the cumulant approximation, a major assumption in DWS/DCS. We present a precise criterion for validity of the cumulant approximation, and in realistic tissue models, identify conditions that invalidate it. We show that, in physiologically relevant scenarios, the first cumulant term for random flow and second cumulant term for Brownian motion alone can cancel each other. In such circumstances, assuming pure Brownian motion of RBCs and the first cumulant approximation, a routine practice in DWS/DCS of BFI, can yield good agreement with data, but only because errors due to two incorrect assumptions cancel out. We conclude that correctly assessing random flow from scattered light dynamics requires going beyond the cumulant approximation and propose a more accurate model to do so.
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Affiliation(s)
- V. N. Du Le
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, USA
| | - Vivek J. Srinivasan
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, USA
- Department of Ophthalmology and Vision Science, University of California Davis, Davis School of Medicine, Sacramento, CA 96817, USA
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23
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Baj J, Sitarz R, Łokaj M, Forma A, Czeczelewski M, Maani A, Garruti G. Preoperative and Intraoperative Methods of Parathyroid Gland Localization and the Diagnosis of Parathyroid Adenomas. Molecules 2020; 25:E1724. [PMID: 32283730 PMCID: PMC7181220 DOI: 10.3390/molecules25071724] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 04/03/2020] [Accepted: 04/08/2020] [Indexed: 02/05/2023] Open
Abstract
Accurate pre-operative determination of parathyroid glands localization is critical in the selection of minimally invasive parathyroidectomy as a surgical treatment approach in patients with primary hyperparathyroidism (PHPT). Its importance cannot be overemphasized as it helps to minimize the harmful side effects associated with damage to the parathyroid glands such as in hypocalcemia, severe hemorrhage or recurrent laryngeal nerve dysfunction. Preoperative and intraoperative methods decrease the incidence of mistakenly injuring the parathyroid glands and allow for the timely diagnosis of various abnormalities, including parathyroid adenomas. This article reviews 139 studies conducted between 1970 and 2020 (49 years). Studies that were reviewed focused on several techniques including application of carbon nanoparticles, carbon nanoparticles with technetium sestamibi (99m Tc-MIBI), Raman spectroscopy, near-infrared autofluorescence, dynamic optical contrast imaging, laser speckle contrast imaging, shear wave elastography, and indocyanine green to test their potential in providing proper parathyroid glands' localization. Apart from reviewing the aforementioned techniques, this study focused on the applications that helped in the detection of parathyroid adenomas. Results suggest that applying all the reviewed techniques significantly improves the possibility of providing proper localization of parathyroid glands, and the application of indocyanine green has proven to be the 'ideal' approach for the diagnosis of parathyroid adenomas.
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Affiliation(s)
- Jacek Baj
- Chair and Department of Anatomy, Medical University of Lublin, 20-950 Lublin, Poland; (R.S.); (A.F.); (A.M.)
| | - Robert Sitarz
- Chair and Department of Anatomy, Medical University of Lublin, 20-950 Lublin, Poland; (R.S.); (A.F.); (A.M.)
- Department of Surgery, Center of Oncology of the Lublin Region St. Jana z Dukli, 20-090 Lublin, Poland;
| | - Marek Łokaj
- Department of Surgery, Center of Oncology of the Lublin Region St. Jana z Dukli, 20-090 Lublin, Poland;
| | - Alicja Forma
- Chair and Department of Anatomy, Medical University of Lublin, 20-950 Lublin, Poland; (R.S.); (A.F.); (A.M.)
| | - Marcin Czeczelewski
- Chair and Department of Forensic Medicine, Medical University of Lublin, 20-950 Lublin, Poland;
| | - Amr Maani
- Chair and Department of Anatomy, Medical University of Lublin, 20-950 Lublin, Poland; (R.S.); (A.F.); (A.M.)
| | - Gabriella Garruti
- Section of Endocrinology, Andrology and Metabolic Diseases, Department of Emergency and Organ Transplantations, University of Bari “Aldo Moro” Medical School, 70124 Bari, Italy;
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24
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Du E, Shen S, Chong SP, Chen N. Multifunctional laser speckle imaging. BIOMEDICAL OPTICS EXPRESS 2020; 11:2007-2016. [PMID: 32341863 PMCID: PMC7173886 DOI: 10.1364/boe.388856] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 03/07/2020] [Accepted: 03/07/2020] [Indexed: 05/02/2023]
Abstract
We have developed a multi-functional laser speckle imaging system, which can be operated in both the surface illumination laser speckle contrast imaging (SI-LSCI) mode and the line scan laser speckle contrast imaging (LS-LSCI) mode. The system has been applied to imaging the chicken embryos to visualize both the blood flow and morphological details of the vasculature. The experimental results demonstrated that LS-LSCI is capable of detecting and quantifying blood flow in blood vessels smaller and deeper than those detectable by conventional SI-LSCI. Furthermore, the line scan mode is also capable of producing depth-resolved absorption-based morphological images of tissue, augmenting flow-based functional images.
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25
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Kholiqov O, Zhou W, Zhang T, Du Le VN, Srinivasan VJ. Time-of-flight resolved light field fluctuations reveal deep human tissue physiology. Nat Commun 2020; 11:391. [PMID: 31959896 PMCID: PMC6971031 DOI: 10.1038/s41467-019-14228-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 12/17/2019] [Indexed: 12/16/2022] Open
Abstract
Red blood cells (RBCs) transport oxygen to tissues and remove carbon dioxide. Diffuse optical flowmetry (DOF) assesses deep tissue RBC dynamics by measuring coherent fluctuations of multiply scattered near-infrared light intensity. While classical DOF measurements empirically correlate with blood flow, they remain far-removed from light scattering physics and difficult to interpret in layered media. To advance DOF measurements closer to the physics, here we introduce an interferometric technique, surmounting challenges of bulk motion to apply it in awake humans. We reveal two measurement dimensions: optical phase, and time-of-flight (TOF), the latter with 22 picosecond resolution. With this multidimensional data, we directly confirm the unordered, or Brownian, nature of optically probed RBC dynamics typically assumed in classical DOF. We illustrate how incorrect absorption assumptions, anisotropic RBC scattering, and layered tissues may confound classical DOF. By comparison, our direct method enables accurate and comprehensive assessment of blood flow dynamics in humans. Diffuse optical flowmetry is widely used to assess blood flow dynamics, but has remained difficult to interpret. Here, the authors use interferometric near-infrared spectroscopy, revealing additional information about optical phase and time-of-flight, and observe the Brownian nature of blood flow dynamics in humans.
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Affiliation(s)
- Oybek Kholiqov
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, USA
| | - Wenjun Zhou
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, USA
| | - Tingwei Zhang
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, USA
| | - V N Du Le
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, USA
| | - Vivek J Srinivasan
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, USA. .,Department of Ophthalmology and Vision Science, University of California Davis, Davis School of Medicine, Sacramento, CA, 96817, USA.
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Sivakumar PS, Kagawa K, Crouzet C, Choi B, Yasutomi K, Kawahito S. Multi-exposure laser speckle contrast imaging using a video-rate multi-tap charge modulation image sensor. OPTICS EXPRESS 2019; 27:26175-26191. [PMID: 31510477 PMCID: PMC6825609 DOI: 10.1364/oe.27.026175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 08/03/2019] [Accepted: 08/13/2019] [Indexed: 05/12/2023]
Abstract
Multi-exposure laser speckle contrast imaging (MELSCI) systems based on high frame rate cameras are suitable for wide-field quantitative measurement of blood flow. However, high-speed camera-based MELSCI requires high power consumption, large memory, and high processing capability, which may lead to relatively large and expensive hardware. To realize a compact and cost-efficient MELSCI system, we discuss an application of the multi-tap CMOS image sensor originally designed for time-of-flight range imaging. This image sensor operated in the global shutter mode and every pixel was provided with multiple charge-storage diodes. Multiple images for different exposures were acquired simultaneously because exposure patterns were programmable to implement an arbitrary exposure duration for each tap. The frame rate was close to video frame rates (30 frames per second (fps)) regardless of the exposure pattern. The feasibility of the proposed method was verified by simulations that were performed with real speckle images captured by a high-speed camera at 40 kfps. Experiments with a four-tap CMOS image sensor demonstrated that a flow speed map was obtained at a moderate frame rate such as 35 fps for a moving ground glass plate and 45 fps for flowing Intralipose, which were linearly moved at speeds of 1-5 mm/s.
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Affiliation(s)
- Panneer Selvam Sivakumar
- Graduate School of Science and Technology, Shizuoka University, 3-5-1, Johoku, Hamamatsu 432-8011, Japan
| | - Keiichiro Kagawa
- Research Institute of Electronics, Shizuoka University, 3-5-1, Johoku, Hamamatsu 432-8011, Japan
| | - Christian Crouzet
- Beckman Laser Institute and Medical Clinic, University of California, Irvine, 1002 Health Sciences Rd, Irvine, CA 92612, USA
| | - Bernard Choi
- Beckman Laser Institute and Medical Clinic, University of California, Irvine, 1002 Health Sciences Rd, Irvine, CA 92612, USA
- Departments of Biomedical Engineering and Surgery, University of California, Irvine, CA 92697, USA
| | - Keita Yasutomi
- Research Institute of Electronics, Shizuoka University, 3-5-1, Johoku, Hamamatsu 432-8011, Japan
| | - Shoji Kawahito
- Research Institute of Electronics, Shizuoka University, 3-5-1, Johoku, Hamamatsu 432-8011, Japan
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Soleimanzad H, Smekens F, Peyronnet J, Juchaux M, Lefebvre O, Bouville D, Magnan C, Gurden H, Pain F. Multiple speckle exposure imaging for the study of blood flow changes induced by functional activation of barrel cortex and olfactory bulb in mice. NEUROPHOTONICS 2019; 6:015008. [PMID: 30854406 PMCID: PMC6400140 DOI: 10.1117/1.nph.6.1.015008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 02/13/2019] [Indexed: 06/09/2023]
Abstract
Speckle contrast imaging allows in vivo imaging of relative blood flow changes. Multiple exposure speckle imaging (MESI) is more accurate than the standard single-exposure method since it allows separating the contribution of the static and moving scatters of the recorded speckle patterns. MESI requires experimental validation on phantoms prior to in vivo experiments to ensure the proper calibration of the system and the robustness of the model. The data analysis relies on the calculation of the speckle contrast for each exposure and a subsequent nonlinear fit to the MESI model to extract the scatterers correlation time and the relative contribution of moving scatters. We have designed two multichannel polydimethylsiloxane chips to study the influence of multiple and static scattering on the accuracy of MESI quantitation. We also propose a method based on standard C++ libraries to implement a computationally efficient analysis of the MESI data. Finally, the system was used to obtain in vivo hemodynamic data on two distinct sensory areas of the mice brain: the barrel cortex and the olfactory bulb.
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Affiliation(s)
- Haleh Soleimanzad
- IMNC, CNRS, Université Paris-Sud, Université Paris-Saclay, Orsay, France
- BFA, CNRS, Université Paris Diderot, Paris, France
| | - François Smekens
- IMNC, CNRS, Université Paris-Sud, Université Paris-Saclay, Orsay, France
| | - Juliette Peyronnet
- IMNC, CNRS, Université Paris-Sud, Université Paris-Saclay, Orsay, France
| | - Marjorie Juchaux
- IMNC, CNRS, Université Paris-Sud, Université Paris-Saclay, Orsay, France
- C2N, CNRS, Université Paris-Sud, Université Paris-Saclay, Palaiseau, France
| | - Olivier Lefebvre
- IMNC, CNRS, Université Paris-Sud, Université Paris-Saclay, Orsay, France
| | - David Bouville
- C2N, CNRS, Université Paris-Sud, Université Paris-Saclay, Palaiseau, France
| | | | - Hirac Gurden
- BFA, CNRS, Université Paris Diderot, Paris, France
| | - Frederic Pain
- IMNC, CNRS, Université Paris-Sud, Université Paris-Saclay, Orsay, France
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Fredriksson I, Hultman M, Strömberg T, Larsson M. Machine learning in multiexposure laser speckle contrast imaging can replace conventional laser Doppler flowmetry. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-11. [PMID: 30675771 PMCID: PMC6985684 DOI: 10.1117/1.jbo.24.1.016001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 12/17/2018] [Indexed: 05/20/2023]
Abstract
Laser speckle contrast imaging (LSCI) enables video rate imaging of blood flow. However, its relation to tissue blood perfusion is nonlinear and depends strongly on exposure time. By contrast, the perfusion estimate from the slower laser Doppler flowmetry (LDF) technique has a relationship to blood perfusion that is better understood. Multiexposure LSCI (MELSCI) enables a perfusion estimate closer to the actual perfusion than that using a single exposure time. We present and evaluate a method that utilizes contrasts from seven exposure times between 1 and 64 ms to calculate a perfusion estimate that resembles the perfusion estimate from LDF. The method is based on artificial neural networks (ANN) for fast and accurate processing of MELSCI contrasts to perfusion. The networks are trained using modeling of Doppler histograms and speckle contrasts from tissue models. The importance of accounting for noise is demonstrated. Results show that by using ANN, MELSCI data can be processed to LDF perfusion with high accuracy, with a correlation coefficient R = 1.000 for noise-free data, R = 0.993 when a moderate degree of noise is present, and R = 0.995 for in vivo data from an occlusion-release experiment.
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Affiliation(s)
- Ingemar Fredriksson
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
- Perimed AB, Stockholm, Sweden
| | - Martin Hultman
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
| | - Tomas Strömberg
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
| | - Marcus Larsson
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
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29
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Ringuette D, Nauenberg J, Monnier PP, Carlen PL, Levi O. Data compression and improved registration for laser speckle contrast imaging of rodent brains. BIOMEDICAL OPTICS EXPRESS 2018; 9:5615-5634. [PMID: 30460150 PMCID: PMC6238931 DOI: 10.1364/boe.9.005615] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 08/30/2018] [Accepted: 09/13/2018] [Indexed: 05/16/2023]
Abstract
Single-frame blood flow maps from laser speckle contrast imaging (LSCI) contain high spatiotemporal variation that obscures high spatial-frequency vascular features, making precise image registration for signal amplification challenging. In this work, novel bivariate standardized moment filters (BSMFs) were used to provide stable measures of vessel edge location, permitting more robust LSCI registration. Relatedly, BSMFs enabled the stable reconstruction of vessel edges from sparsely distributed blood flow map outliers, which were found to retain most of the temporal dynamics. Consequently, data discarding and BSMF-based reconstruction enable efficient real-time quantitative LSCI data compression. Smaller LSCI-kernels produced log-normal blood flow distributions, enhancing sparse-to-dense inference.
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Affiliation(s)
- Dene Ringuette
- The Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, M5S 3G9,
Canada
- Division of Fundamental Neurobiology, Toronto Western Research Institute, 60 Leonard Ave, Toronto, Ontario M5T 2S8,
Canada
| | - Jacob Nauenberg
- The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario, M5S 3G4,
Canada
| | - Philippe P. Monnier
- Division of Fundamental Neurobiology, Toronto Western Research Institute, 60 Leonard Ave, Toronto, Ontario M5T 2S8,
Canada
| | - Peter L. Carlen
- The Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, M5S 3G9,
Canada
- Division of Fundamental Neurobiology, Toronto Western Research Institute, 60 Leonard Ave, Toronto, Ontario M5T 2S8,
Canada
| | - Ofer Levi
- The Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, M5S 3G9,
Canada
- The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario, M5S 3G4,
Canada
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30
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Liu J, Wang H, Wang P, Jin Z, Li W, Zhang H, Shen Z, Xiong D. Establishing the quantitative relationship between diffuse speckle contrast analysis signals with absolute blood flow. BIOMEDICAL OPTICS EXPRESS 2018; 9:4792-4806. [PMID: 30319903 PMCID: PMC6179414 DOI: 10.1364/boe.9.004792] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 08/15/2018] [Accepted: 09/06/2018] [Indexed: 06/08/2023]
Abstract
Diffuse speckle contrast analysis (DSCA) measures blood flow in deep tissues by taking advantage of the sensitivity of the speckle contrast signal to red blood cells (RBCs) motions. However, there has yet to be presented a clearly defined relationship between the absolute blood flow BFabs and the measured speckle contrast signal. Here, we derive an expression of linear approximation function for speckle contrast, taking into account both shear-induced diffusive and correlated advective RBCs motions in the vessels. We provide a linear relationship between the slope k slope of this linear function and BFabs. The feasibility of this relationship is validated by Monte Carlo simulations of heterogeneous tissue with varying vessel radii. Furthermore, based on this quantitative relationship, we can determine the relative contributions of diffusive RBCs motion on the reduction of speckle contrast, considering different vascular morphology and flow profiles.
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Affiliation(s)
- Jialin Liu
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No. 88 Keling Street, Suzhou 215163, China
| | - Haiyang Wang
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No. 88 Keling Street, Suzhou 215163, China
| | - Peipei Wang
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No. 88 Keling Street, Suzhou 215163, China
| | - Zhiliang Jin
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No. 88 Keling Street, Suzhou 215163, China
| | - Weimin Li
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No. 88 Keling Street, Suzhou 215163, China
| | - Hongchao Zhang
- School of Science, Nanjing University of Science and Technology, No. 200 Xiaolingwei Street, Nanjing 210094, China
| | - Zhonghua Shen
- School of Science, Nanjing University of Science and Technology, No. 200 Xiaolingwei Street, Nanjing 210094, China
| | - Daxi Xiong
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No. 88 Keling Street, Suzhou 215163, China
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Sullender CT, Mark AE, Clark TA, Esipova TV, Vinogradov SA, Jones TA, Dunn AK. Imaging of cortical oxygen tension and blood flow following targeted photothrombotic stroke. NEUROPHOTONICS 2018; 5:035003. [PMID: 30137881 PMCID: PMC6062776 DOI: 10.1117/1.nph.5.3.035003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 07/02/2018] [Indexed: 05/24/2023]
Abstract
We present a dual-modality imaging system combining laser speckle contrast imaging and oxygen-dependent quenching of phosphorescence to simultaneously map cortical blood flow and oxygen tension ( pO 2 ) in mice. Phosphorescence signal localization is achieved through the use of a digital micromirror device (DMD) that allows for selective excitation of arbitrary regions of interest. By targeting both excitation maxima of the oxygen-sensitive Oxyphor PtG4, we are able to examine the effects of excitation wavelength on the measured phosphorescence lifetime. We demonstrate the ability to measure the differences in pO 2 between arteries and veins and large changes during a hyperoxic challenge. We dynamically monitor blood flow and pO 2 during DMD-targeted photothrombotic occlusion of an arteriole and highlight the presence of an ischemia-induced depolarization. Chronic tracking of the ischemic lesion over eight days revealed a rapid recovery, with the targeted vessel fully reperfusing and pO 2 returning to baseline values within five days. This system has broad applications for studying the acute and chronic pathophysiology of ischemic stroke and other vascular diseases of the brain.
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Affiliation(s)
- Colin T. Sullender
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Andrew E. Mark
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Taylor A. Clark
- University of Texas at Austin, Department of Psychology, Austin, Texas, United States
- University of Texas at Austin, Institute for Neuroscience, Austin, Texas, United States
| | - Tatiana V. Esipova
- University of Pennsylvania, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
| | - Sergei A. Vinogradov
- University of Pennsylvania, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
| | - Theresa A. Jones
- University of Texas at Austin, Department of Psychology, Austin, Texas, United States
- University of Texas at Austin, Institute for Neuroscience, Austin, Texas, United States
| | - Andrew K. Dunn
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
- University of Texas at Austin, Institute for Neuroscience, Austin, Texas, United States
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32
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Vaz PG, Humeau-Heurtier A, Figueiras E, Correia C, Cardoso J. Effect of static scatterers in laser speckle contrast imaging: an experimental study on correlation and contrast. ACTA ACUST UNITED AC 2017; 63:015024. [DOI: 10.1088/1361-6560/aa9f3a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Intraoperative Assessment of Parathyroid Viability using Laser Speckle Contrast Imaging. Sci Rep 2017; 7:14798. [PMID: 29093531 PMCID: PMC5665975 DOI: 10.1038/s41598-017-14941-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 10/18/2017] [Indexed: 11/08/2022] Open
Abstract
Post-surgical hypoparathyroidism and hypocalcemia are known to occur after nearly 50% of all thyroid surgeries as a result of accidental disruption of blood supply to healthy parathyroid glands, which are responsible for regulating calcium. However, there are currently no clinical methods for accurately identifying compromised glands and the surgeon relies on visual assessment alone to determine if any gland(s) should be excised and auto-transplanted. Here, we present Laser Speckle Contrast Imaging (LSCI) for real-time assessment of parathyroid viability. Taking an experienced surgeon's visual assessment as the gold standard, LSCI can be used to distinguish between well vascularized (n = 32) and compromised (n = 27) parathyroid glands during thyroid surgery with an accuracy of 91.5%. Ability to detect vascular compromise with LSCI was validated in parathyroidectomies. Results showed that this technique is able to detect parathyroid gland devascularization before it is visually apparent to the surgeon. Measurements can be performed in real-time and without the need to turn off operating room lights. LSCI shows promise as a real-time, contrast-free, objective method for helping reduce hypoparathyroidism after thyroid surgery.
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Liu J, Zhang H, Lu J, Ni X, Shen Z. Simultaneously extracting multiple parameters via multi-distance and multi-exposure diffuse speckle contrast analysis. BIOMEDICAL OPTICS EXPRESS 2017; 8:4537-4550. [PMID: 29082083 PMCID: PMC5654798 DOI: 10.1364/boe.8.004537] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 09/03/2017] [Accepted: 09/14/2017] [Indexed: 05/25/2023]
Abstract
Recent advancements in diffuse speckle contrast analysis (DSCA) have opened the path for noninvasive acquisition of deep tissue microvasculature blood flow. In fact, in addition to blood flow index αDB , the variations of tissue optical absorption μa , reduced scattering coefficients [Formula: see text], as well as coherence factor β can modulate temporal fluctuations of speckle patterns. In this study, we use multi-distance and multi-exposure DSCA (MDME-DSCA) to simultaneously extract multiple parameters such as μa , [Formula: see text], αDB , and β. The validity of MDME-DSCA has been validated by the simulated data and phantoms experiments. Moreover, as a comparison, the results also show that it is impractical to simultaneously obtain multiple parameters by multi-exposure DSCA (ME-DSCA).
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35
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Fredriksson I, Larsson M. Vessel packaging effect in laser speckle contrast imaging and laser Doppler imaging. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-7. [PMID: 29019179 DOI: 10.1117/1.jbo.22.10.106005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 09/12/2017] [Indexed: 06/07/2023]
Abstract
Laser speckle-based techniques are frequently used to assess microcirculatory blood flow. Perfusion estimates are calculated either by analyzing the speckle fluctuations over time as in laser Doppler flowmetry (LDF), or by analyzing the speckle contrast as in laser speckle contrast imaging (LSCI). The perfusion estimates depend on the amount of blood and its speed distribution. However, the perfusion estimates are commonly given in arbitrary units as they are nonlinear and depend on the magnitude and the spatial distribution of the optical properties in the tissue under investigation. We describe how the spatial confinement of blood to vessels, called the vessel packaging effect, can be modeled in LDF and LSCI, which affect the Doppler power spectra and speckle contrast, and the underlying bio-optical mechanisms for these effects. As an example, the perfusion estimate is reduced by 25% for LDF and often more than 50% for LSCI when blood is located in vessels with an average diameter of 40 μm, instead of being homogeneously distributed within the tissue. This significant effect can be compensated for only with knowledge of the average diameter of the vessels in the tissue.
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Affiliation(s)
- Ingemar Fredriksson
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
- Perimed AB, Järfälla-Stockholm, Sweden
| | - Marcus Larsson
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
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36
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Richards LM, Kazmi SS, Olin KE, Waldron JS, Fox DJ, Dunn AK. Intraoperative multi-exposure speckle imaging of cerebral blood flow. J Cereb Blood Flow Metab 2017; 37:3097-3109. [PMID: 28112550 PMCID: PMC5584700 DOI: 10.1177/0271678x16686987] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Multiple studies have demonstrated that laser speckle contrast imaging (LSCI) has high potential to be a valuable cerebral blood flow monitoring technique during neurosurgery. However, the quantitative accuracy and sensitivity of LSCI is limited, and highly dependent on the exposure time. An extension to LSCI called multi-exposure speckle imaging (MESI) overcomes these limitations, and was evaluated intraoperatively in patients undergoing brain tumor resection. This clinical study ( n = 8) recorded multiple exposure times from the same cortical tissue area spanning 0.5-20 ms, and evaluated images individually as single-exposure LSCI and jointly using the MESI model. This study demonstrated that the MESI estimates provided the broadest flow sensitivity for sampling the flow magnitude in the human brain, closely followed by the shorter exposure times. Conservation of flow analysis on vascular bifurcations was used to validate physiological accuracy, with highly conserved flow estimates (<10%) from both MESI and 1 ms LSCI ( n = 14 branches). The MESI model had high goodness-of-fit with proper image calibration and acquisition, and was used to monitor blood flow changes after tissue cautery. Results from this study demonstrate that intraoperative MESI can be performed with high quantitative accuracy and sensitivity for cerebral blood flow monitoring.
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Affiliation(s)
- Lisa M Richards
- 1 Department of Biomedical Engineering, The University of Texas at Austin, Austin TX, USA
| | - Sm Shams Kazmi
- 1 Department of Biomedical Engineering, The University of Texas at Austin, Austin TX, USA
| | - Katherine E Olin
- 1 Department of Biomedical Engineering, The University of Texas at Austin, Austin TX, USA
| | - James S Waldron
- 2 NeuroTexas Institute, St. David's Medical Center, Austin, USA
| | - Douglas J Fox
- 2 NeuroTexas Institute, St. David's Medical Center, Austin, USA
| | - Andrew K Dunn
- 1 Department of Biomedical Engineering, The University of Texas at Austin, Austin TX, USA
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37
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Abdurashitov A, Bragina O, Sindeeva O, Sergey S, Semyachkina-Glushkovskaya OV, Tuchin VV. Off-axis holographic laser speckle contrast imaging of blood vessels in tissues. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:91514. [PMID: 28444152 DOI: 10.1117/1.jbo.22.9.091514] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Accepted: 03/27/2017] [Indexed: 06/07/2023]
Abstract
Laser speckle contrast imaging (LSCI) has become one of the most common tools for functional imaging in tissues. Incomplete theoretical description and sophisticated interpretation of measurement results are completely sidelined by a low-cost and simple hardware, fastness, consistent results, and repeatability. In addition to the relatively low measuring volume with around 700 ?? ? m of the probing depth for the visible spectral range of illumination, there is no depth selectivity in conventional LSCI configuration; furthermore, in a case of high NA objective, the actual penetration depth of light in tissues is greater than depth of field (DOF) of an imaging system. Thus, the information about these out-of-focus regions persists in the recorded frames but cannot be retrieved due to intensity-based registration method. We propose a simple modification of LSCI system based on the off-axis holography to introduce after-registration refocusing ability to overcome both depth-selectivity and DOF problems as well as to get the potential possibility of producing a cross-section view of the specimen.
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Affiliation(s)
- Arkady Abdurashitov
- Saratov National Research State University, Research-Educational Institute of Optics and Biophotonics, Saratov, Russia
| | - Olga Bragina
- Saratov National Research State University, Department of Human and Animal Physiology, Saratov, RussiacUniversity of New Mexico School of Medicine, Department of Neurosurgery, Albuquerque, New Mexico, United States
| | - Olga Sindeeva
- Saratov National Research State University, Department of Human and Animal Physiology, Saratov, RussiadQueen Mary University of London, School of Engineering and Materials Science, London, United KingdomeSaratov National Research State University, Remote Controlled Theranostic Systems Laboratory, Saratov, Russia
| | - Sindeev Sergey
- Saratov National Research State University, Department of Human and Animal Physiology, Saratov, Russia
| | | | - Valery V Tuchin
- Saratov National Research State University, Research-Educational Institute of Optics and Biophotonics, Saratov, RussiafInstitute of Precision Mechanics and Control RAS, Laboratory of Laser Diagnostics of Technical and Living Systems, Saratov, RussiagNational Research Tomsk State University, Interdisciplinary Laboratory of Biophotonics, Tomsk, Russia
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38
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Liu J, Zhang H, Lu J, Ni X, Shen Z. Quantitative model of diffuse speckle contrast analysis for flow measurement. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:76016. [PMID: 28742921 DOI: 10.1117/1.jbo.22.7.076016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 06/30/2017] [Indexed: 05/22/2023]
Abstract
Diffuse speckle contrast analysis (DSCA) is a noninvasive optical technique capable of monitoring deep tissue blood flow. However, a detailed study of the speckle contrast model for DSCA has yet to be presented. We deduced the theoretical relationship between speckle contrast and exposure time and further simplified it to a linear approximation model. The feasibility of this linear model was validated by the liquid phantoms which demonstrated that the slope of this linear approximation was able to rapidly determine the Brownian diffusion coefficient of the turbid media at multiple distances using multiexposure speckle imaging. Furthermore, we have theoretically quantified the influence of optical property on the measurements of the Brownian diffusion coefficient which was a consequence of the fact that the slope of this linear approximation was demonstrated to be equal to the inverse of correlation time of the speckle.
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Affiliation(s)
- Jialin Liu
- Nanjing University of Science and Technology, School of Science, Nanjing, China
| | - Hongchao Zhang
- Nanjing University of Science and Technology, School of Science, Nanjing, China
| | - Jian Lu
- Nanjing University of Science and Technology, School of Science, Nanjing, China
| | - Xiaowu Ni
- Nanjing University of Science and Technology, School of Science, Nanjing, China
| | - Zhonghua Shen
- Nanjing University of Science and Technology, School of Science, Nanjing, China
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39
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Sakadžić S, Boas DA, Carp S. Theoretical model of blood flow measurement by diffuse correlation spectroscopy. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:27006. [PMID: 28241276 PMCID: PMC5325034 DOI: 10.1117/1.jbo.22.2.027006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 01/30/2017] [Indexed: 05/03/2023]
Abstract
Diffuse correlation spectroscopy (DCS) is a noninvasive method to quantify tissue perfusion from measurements of the intensity temporal autocorrelation function of diffusely scattered light. However, DCS autocorrelation function measurements in tissue better match theoretical predictions based on the diffusive motion of the scatterers than those based on a model where the advective nature of blood flow dominates the stochastic properties of the scattered light. We have recently shown using Monte Carlo (MC) simulations and assuming a simplistic vascular geometry and laminar flow profile that the diffusive nature of the DCS autocorrelation function decay is likely a result of the shear-induced diffusion of the red blood cells. Here, we provide theoretical derivations supporting and generalizing the previous MC results. Based on the theory of diffusing-wave spectroscopy, we derive an expression for the autocorrelation function along the photon path through a vessel that takes into account both diffusive and advective scatterer motion, and we provide the solution for the DCS autocorrelation function in a semi-infinite geometry. We also derive the correlation diffusion and correlation transfer equation, which can be applied for an arbitrary sample geometry. Further, we propose a method to take into account realistic vascular morphology and flow profile.
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Affiliation(s)
- Sava Sakadžić
- Massachusetts General Hospital and Harvard Medical School, Optics Division, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
- Address all correspondence to: Sava Sakadžić, E-mail:
| | - David A. Boas
- Massachusetts General Hospital and Harvard Medical School, Optics Division, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
| | - Stefan Carp
- Massachusetts General Hospital and Harvard Medical School, Optics Division, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
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40
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Fredriksson I, Larsson M. On the equivalence and differences between laser Doppler flowmetry and laser speckle contrast analysis. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:126018. [PMID: 28008449 DOI: 10.1117/1.jbo.21.12.126018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 11/30/2016] [Indexed: 05/06/2023]
Abstract
Laser Doppler flowmetry (LDF) and laser speckle contrast analysis (LASCA) both utilize the spatiotemporal properties of laser speckle patterns to assess microcirculatory blood flow in tissue. Although the techniques analyze the speckle pattern differently, there is a close relationship between them. We present a theoretical overview describing how the LDF power spectrum and the LASCA contrast can be calculated from each other, and how both these can be calculated from an optical Doppler spectrum containing various degrees of Doppler shifted light. The theoretical relationships are further demonstrated using time-resolved speckle simulations. A wide range of Monte Carlo simulated tissue models is then used to show how perfusion estimates for LDF and LASCA are affected by changes in blood concentration and speed distribution, as well as by geometrical and optical properties. We conclude that perfusion estimates from conventional single exposure time LASCA are in general more sensitive to changes in optical and geometrical properties and are less accurate in the prediction of real perfusion changes, especially speed changes. Since there is a theoretical one-to-one relationship between Doppler power spectrum and contrast, one can conclude that those drawbacks with the LASCA technique can be overcome using a multiple exposure time setup.
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Affiliation(s)
- Ingemar Fredriksson
- Linköping University, Department of Biomedical Engineering, 581 85 Linköping, SwedenbPerimed AB, Datavägen 9A, 175 43 Järfälla-Stockholm, Sweden
| | - Marcus Larsson
- Linköping University, Department of Biomedical Engineering, 581 85 Linköping, Sweden
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41
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Choi WJ, Li Y, Qin W, Wang RK. Cerebral capillary velocimetry based on temporal OCT speckle contrast. BIOMEDICAL OPTICS EXPRESS 2016; 7:4859-4873. [PMID: 28018711 PMCID: PMC5175537 DOI: 10.1364/boe.7.004859] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 10/21/2016] [Accepted: 10/27/2016] [Indexed: 05/15/2023]
Abstract
We propose a new optical coherence tomography (OCT) based method to measure red blood cell (RBC) velocities of single capillaries in the cortex of rodent brain. This OCT capillary velocimetry exploits quantitative laser speckle contrast analysis to estimate speckle decorrelation rate from the measured temporal OCT speckle signals, which is related to microcirculatory flow velocity. We hypothesize that OCT signal due to sub-surface capillary flow can be treated as the speckle signal in the single scattering regime and thus its time scale of speckle fluctuations can be subjected to single scattering laser speckle contrast analysis to derive characteristic decorrelation time. To validate this hypothesis, OCT measurements are conducted on a single capillary flow phantom operating at preset velocities, in which M-mode B-frames are acquired using a high-speed OCT system. Analysis is then performed on the time-varying OCT signals extracted at the capillary flow, exhibiting a typical inverse relationship between the estimated decorrelation time and absolute RBC velocity, which is then used to deduce the capillary velocities. We apply the method to in vivo measurements of mouse brain, demonstrating that the proposed approach provides additional useful information in the quantitative assessment of capillary hemodynamics, complementary to that of OCT angiography.
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42
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Khaksari K, Kirkpatrick SJ. Laser speckle contrast imaging is sensitive to advective flux. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:76001. [PMID: 27367424 DOI: 10.1117/1.jbo.21.7.076001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 06/08/2016] [Indexed: 06/06/2023]
Abstract
Unlike laser Doppler flowmetry, there has yet to be presented a clear description of the physical variables that laser speckle contrast imaging (LSCI) is sensitive to. Herein, we present a theoretical basis for demonstrating that LSCI is sensitive to total flux and, in particular, the summation of diffusive flux and advective flux. We view LSCI from the perspective of mass transport and briefly derive the diffusion with drift equation in terms of an LSCI experiment. This equation reveals the relative sensitivity of LSCI to both diffusive flux and advective flux and, thereby, to both concentration and the ordered velocity of the scattering particles. We demonstrate this dependence through a short series of flow experiments that yield relationships between the calculated speckle contrast and the concentration of the scatterers (manifesting as changes in scattering coefficient), between speckle contrast and the velocity of the scattering fluid, and ultimately between speckle contrast and advective flux. Finally, we argue that the diffusion with drift equation can be used to support both Lorentzian and Gaussian correlation models that relate observed contrast to the movement of the scattering particles and that a weighted linear combination of these two models is likely the most appropriate model for relating speckle contrast to particle motion.
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43
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Choi WJ, Qin W, Chen CL, Wang J, Zhang Q, Yang X, Gao BZ, Wang RK. Characterizing relationship between optical microangiography signals and capillary flow using microfluidic channels. BIOMEDICAL OPTICS EXPRESS 2016; 7:2709-28. [PMID: 27446700 PMCID: PMC4948624 DOI: 10.1364/boe.7.002709] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 06/15/2016] [Accepted: 06/15/2016] [Indexed: 05/17/2023]
Abstract
Optical microangiography (OMAG) is a powerful optical angio-graphic tool to visualize micro-vascular flow in vivo. Despite numerous demonstrations for the past several years of the qualitative relationship between OMAG and flow, no convincing quantitative relationship has been proven. In this paper, we attempt to quantitatively correlate the OMAG signal with flow. Specifically, we develop a simplified analytical model of the complex OMAG, suggesting that the OMAG signal is a product of the number of particles in an imaging voxel and the decorrelation of OCT (optical coherence tomography) signal, determined by flow velocity, inter-frame time interval, and wavelength of the light source. Numerical simulation with the proposed model reveals that if the OCT amplitudes are correlated, the OMAG signal is related to a total number of particles across the imaging voxel cross-section per unit time (flux); otherwise it would be saturated but its strength is proportional to the number of particles in the imaging voxel (concentration). The relationship is validated using microfluidic flow phantoms with various preset flow metrics. This work suggests OMAG is a promising quantitative tool for the assessment of vascular flow.
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Affiliation(s)
- Woo June Choi
- Department of Bioengineering, University of Washington, 3720 15th NE, Seattle, WA 98195, USA
- These authors contributed equally to this work
| | - Wan Qin
- Department of Bioengineering, University of Washington, 3720 15th NE, Seattle, WA 98195, USA
- These authors contributed equally to this work
| | - Chieh-Li Chen
- Department of Bioengineering, University of Washington, 3720 15th NE, Seattle, WA 98195, USA
| | - Jingang Wang
- Department of Bioengineering, University of Washington, 3720 15th NE, Seattle, WA 98195, USA
| | - Qinqin Zhang
- Department of Bioengineering, University of Washington, 3720 15th NE, Seattle, WA 98195, USA
| | - Xiaoqi Yang
- Department of Bioengineering and COMSET, Clemson University, Clemson, SC 29634, USA
| | - Bruce Z. Gao
- Department of Bioengineering and COMSET, Clemson University, Clemson, SC 29634, USA
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, 3720 15th NE, Seattle, WA 98195, USA
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44
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Khaksari K, Kirkpatrick SJ. Combined effects of scattering and absorption on laser speckle contrast imaging. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:76002. [PMID: 27380448 DOI: 10.1117/1.jbo.21.7.076002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 05/18/2016] [Indexed: 05/20/2023]
Abstract
Several variables may affect the local contrast values in laser speckle contrast imaging (LSCI), irrespective of relative motion. It has been suggested that the optical properties of the moving fluid and surrounding tissues can affect LSCI values. However, a detailed study of this has yet to be presented. In this work, we examined the combined effects of the reduced scattering and absorption coefficients on LSCI. This study employs fluid phantoms with different optical properties that were developed to mimic whole blood with varying hematocrit levels. These flow phantoms were imaged with an LSCI system developed for this study. The only variable parameter was the optical properties of the flowing fluid. A negative linear relationship was seen between the changes in contrast and changes in reduced scattering coefficient, absorption coefficient, and total attenuation coefficient. The change in contrast observed due to an increase in the scattering coefficient was greater than what was observed with an increase in the absorption coefficient. The results indicate that optical properties affect contrast values and that they should be considered in the interpretation of LSCI data.
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45
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Postnov DD, Tuchin VV, Sosnovtseva O. Estimation of vessel diameter and blood flow dynamics from laser speckle images. BIOMEDICAL OPTICS EXPRESS 2016; 7:2759-68. [PMID: 27446704 PMCID: PMC4948628 DOI: 10.1364/boe.7.002759] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 06/10/2016] [Accepted: 06/16/2016] [Indexed: 05/02/2023]
Abstract
Laser speckle imaging is a rapidly developing method to study changes of blood velocity in the vascular networks. However, to assess blood flow and vascular responses it is crucial to measure vessel diameter in addition to blood velocity dynamics. We suggest an algorithm that allows for dynamical masking of a vessel position and measurements of it's diameter from laser speckle images. This approach demonstrates high reliability and stability.
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Affiliation(s)
- Dmitry D. Postnov
- Department of Biomedical Sciences, Copenhagen University, Blegdamsvej 3, 2200 Copenhagen N,
Denmark
| | - Valery V. Tuchin
- Research-Educational Institute of Optics and Biophotonics, Saratov National Research State University, Astrakhanskaya Str. 83, 410012 Saratov,
Russia
- Institute of Precision Mechanics and Control RAS, Rabochaya str. 24, 410028 Saratov,
Russia
- Interdisciplinary Laboratory of Biophotonics, Tomsk National Research State University, 634050 Tomsk,
Russia
| | - Olga Sosnovtseva
- Department of Biomedical Sciences, Copenhagen University, Blegdamsvej 3, 2200 Copenhagen N,
Denmark
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46
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Nadort A, Kalkman K, van Leeuwen TG, Faber DJ. Quantitative blood flow velocity imaging using laser speckle flowmetry. Sci Rep 2016; 6:25258. [PMID: 27126250 PMCID: PMC4850477 DOI: 10.1038/srep25258] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 04/13/2016] [Indexed: 11/16/2022] Open
Abstract
Laser speckle flowmetry suffers from a debated quantification of the inverse relation between decorrelation time (τc) and blood flow velocity (V), i.e. 1/τc = αV. Using a modified microcirculation imager (integrated sidestream dark field - laser speckle contrast imaging [SDF-LSCI]), we experimentally investigate on the influence of the optical properties of scatterers on α in vitro and in vivo. We found a good agreement to theoretical predictions within certain limits for scatterer size and multiple scattering. We present a practical model-based scaling factor to correct for multiple scattering in microcirculatory vessels. Our results show that SDF-LSCI offers a quantitative measure of flow velocity in addition to vessel morphology, enabling the quantification of the clinically relevant blood flow, velocity and tissue perfusion.
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Affiliation(s)
- Annemarie Nadort
- Department of Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, P.O. Box 22700, 1100 DE Amsterdam, The Netherlands.,ARC Centre of Excellence for Nanoscale BioPhotonics, Macquarie University, Sydney 2109, NSW Australia
| | - Koen Kalkman
- Department of Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, P.O. Box 22700, 1100 DE Amsterdam, The Netherlands
| | - Ton G van Leeuwen
- Department of Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, P.O. Box 22700, 1100 DE Amsterdam, The Netherlands
| | - Dirk J Faber
- Department of Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, P.O. Box 22700, 1100 DE Amsterdam, The Netherlands
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Davis MA, Gagnon L, Boas DA, Dunn AK. Sensitivity of laser speckle contrast imaging to flow perturbations in the cortex. BIOMEDICAL OPTICS EXPRESS 2016; 7:759-75. [PMID: 27231587 PMCID: PMC4866454 DOI: 10.1364/boe.7.000759] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 01/27/2016] [Accepted: 01/28/2016] [Indexed: 05/18/2023]
Abstract
Laser speckle contrast imaging has become a ubiquitous tool for imaging blood flow in a variety of tissues. However, due to its widefield imaging nature, the measured speckle contrast is a depth integrated quantity and interpretation of baseline values and the depth dependent sensitivity of those values to changes in underlying flow has not been thoroughly evaluated. Using dynamic light scattering Monte Carlo simulations, the sensitivity of the autocorrelation function and speckle contrast to flow changes in the cerebral cortex was extensively examined. These simulations demonstrate that the sensitivity of the inverse autocorrelation time, [Formula: see text], varies across the field of view: directly over surface vessels [Formula: see text] is strongly localized to the single vessel, while parenchymal ROIs have a larger sensitivity to flow changes at depths up to 500 μm into the tissue and up to 200 μm lateral to the ROI. It is also shown that utilizing the commonly used models the relate [Formula: see text] to flow resulted in nearly the same sensitivity to the underlying flow, but fail to accurately relate speckle contrast values to absolute [Formula: see text].
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Affiliation(s)
- Mitchell A. Davis
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712,
USA
| | - Louis Gagnon
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129,
USA
| | - David A. Boas
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129,
USA
| | - Andrew K. Dunn
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712,
USA
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48
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Vaz PG, Humeau-Heurtier A, Figueiras E, Correia C, Cardoso J. Laser Speckle Imaging to Monitor Microvascular Blood Flow: A Review. IEEE Rev Biomed Eng 2016; 9:106-20. [DOI: 10.1109/rbme.2016.2532598] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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49
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Semyachkina-Glushkovskaya O, Pavlov A, Kurths J, Borisova E, Gisbrecht A, Sindeeva O, Abdurashitov A, Shirokov A, Navolokin N, Zinchenko E, Gekalyuk A, Ulanova M, Zhu D, Luo Q, Tuchin V. Optical monitoring of stress-related changes in the brain tissues and vessels associated with hemorrhagic stroke in newborn rats. BIOMEDICAL OPTICS EXPRESS 2015; 6:4088-97. [PMID: 26504656 PMCID: PMC4605065 DOI: 10.1364/boe.6.004088] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 08/26/2015] [Accepted: 09/18/2015] [Indexed: 05/04/2023]
Abstract
Stress is a major factor for a risk of cerebrovascular catastrophes. Studying of mechanisms underlying stress-related brain-injures in neonates is crucial for development of strategy to prevent of neonatal stroke. Here, using a model of sound-stress-induced intracranial hemorrhages in newborn rats and optical methods, we found that cerebral veins are more sensitive to the deleterious effect of stress than arteries and microvessels. The development of venous insufficiency with decreased blood outflow from the brain accompanied by hypoxia, reduction of complexity of venous blood flow and high production of beta-arrestin-1 are possible mechanisms responsible for a risk of neonatal hemorrhagic stroke.
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Affiliation(s)
- Oxana Semyachkina-Glushkovskaya
- Saratov State University, Astrakhanskaya Str. 83, Saratov 410012, Russia
- Huazhong University of Science and Technology, Wuhan 430074, China
| | - Alexey Pavlov
- Saratov State University, Astrakhanskaya Str. 83, Saratov 410012, Russia
| | - Jürgen Kurths
- Huazhong University of Science and Technology, Wuhan 430074, China
- Potsdam Institute for Climate Impact Research, Telegrafenberg A31, 14473 Potsdam, Germany
| | - Ekaterina Borisova
- Institute of Electronics, Bulgarian Academy of Sciences, Tsarigradsko Chaussee 72, Sofia 1784, Bulgaria
| | - Alexander Gisbrecht
- Institute of Electronics, Bulgarian Academy of Sciences, Tsarigradsko Chaussee 72, Sofia 1784, Bulgaria
| | - Olga Sindeeva
- Saratov State University, Astrakhanskaya Str. 83, Saratov 410012, Russia
| | | | - Alexander Shirokov
- Institute of Bioorganic Chemistry, Russian Academy of Sciences, Entusiastov Str.13, Saratov 410049, Russia
| | | | | | - Artem Gekalyuk
- Saratov State University, Astrakhanskaya Str. 83, Saratov 410012, Russia
| | - Maria Ulanova
- Saratov State University, Astrakhanskaya Str. 83, Saratov 410012, Russia
| | - Dan Zhu
- Huazhong University of Science and Technology, Wuhan 430074, China
| | - Qingming Luo
- Huazhong University of Science and Technology, Wuhan 430074, China
| | - Valery Tuchin
- Saratov State University, Astrakhanskaya Str. 83, Saratov 410012, Russia
- Huazhong University of Science and Technology, Wuhan 430074, China
- Laboratory of Biophotonics, Tomsk State University, Tomsk 634050, Russia
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50
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Kazmi SMS, Wu RK, Dunn AK. Evaluating multi-exposure speckle imaging estimates of absolute autocorrelation times. OPTICS LETTERS 2015; 40:3643-3646. [PMID: 26258378 DOI: 10.1364/ol.40.003643] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Multi-exposure speckle imaging (MESI) is a camera-based flow-imaging technique for quantitative blood-flow monitoring by mapping the speckle-contrast dependence on camera exposure duration. The ability of laser speckle contrast imaging to measure the temporal dynamics of backscattered and interfering coherent fields, in terms of the accuracy of autocorrelation measurements, is a major unresolved issue in quantitative speckle flowmetry. MESI fits for a number of parameters including an estimate of the electric field autocorrelation decay time from the imaged speckles. We compare the MESI-determined correlation times in vitro and in vivo with accepted true values from direct temporal measurements acquired with a photon-counting photon-multiplier tube and an autocorrelator board. The correlation times estimated by MESI in vivo remain on average within 14±11% of those obtained from direct temporal autocorrelation measurements, demonstrating that MESI yields highly comparable statistics of the time-varying fields that can be useful for applications seeking not only quantitative blood flow dynamics but also absolute perfusion.
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