1
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Tan B, Sim R, Chua J, Wong DWK, Yao X, Garhöfer G, Schmidl D, Werkmeister RM, Schmetterer L. Approaches to quantify optical coherence tomography angiography metrics. ANNALS OF TRANSLATIONAL MEDICINE 2020; 8:1205. [PMID: 33241054 PMCID: PMC7576021 DOI: 10.21037/atm-20-3246] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Optical coherence tomography (OCT) has revolutionized the field of ophthalmology in the last three decades. As an OCT extension, OCT angiography (OCTA) utilizes a fast OCT system to detect motion contrast in ocular tissue and provides a three-dimensional representation of the ocular vasculature in a non-invasive, dye-free manner. The first OCT machine equipped with OCTA function was approved by U.S. Food and Drug Administration in 2016 and now it is widely applied in clinics. To date, numerous methods have been developed to aid OCTA interpretation and quantification. In this review, we focused on the workflow of OCTA-based interpretation, beginning from the generation of the OCTA images using signal decorrelation, which we divided into intensity-based, phase-based and phasor-based methods. We further discussed methods used to address image artifacts that are commonly observed in clinical settings, to the algorithms for image enhancement, binarization, and OCTA metrics extraction. We believe a better grasp of these technical aspects of OCTA will enhance the understanding of the technology and its potential application in disease diagnosis and management. Moreover, future studies will also explore the use of ocular OCTA as a window to link ocular vasculature to the function of other organs such as the kidney and brain.
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Affiliation(s)
- Bingyao Tan
- Institute for Health Technologies, Nanyang Technological University, Singapore, Singapore.,Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.,SERI-NTU Advanced Ocular Engineering (STANCE) Program, Nanyang Technological University, Singapore, Singapore
| | - Ralene Sim
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
| | - Jacqueline Chua
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.,Academic Clinical Program, Duke-NUS Medical School, Singapore, Singapore
| | - Damon W K Wong
- Institute for Health Technologies, Nanyang Technological University, Singapore, Singapore.,Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.,SERI-NTU Advanced Ocular Engineering (STANCE) Program, Nanyang Technological University, Singapore, Singapore
| | - Xinwen Yao
- Institute for Health Technologies, Nanyang Technological University, Singapore, Singapore.,Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.,SERI-NTU Advanced Ocular Engineering (STANCE) Program, Nanyang Technological University, Singapore, Singapore
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Doreen Schmidl
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - René M Werkmeister
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Leopold Schmetterer
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.,SERI-NTU Advanced Ocular Engineering (STANCE) Program, Nanyang Technological University, Singapore, Singapore.,Academic Clinical Program, Duke-NUS Medical School, Singapore, Singapore.,Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.,Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore, Singapore.,Department of Ophthalmology, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.,Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland
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2
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Marques AJ, Reyes R, Pasarikovski CR, Chen C, Ramjist J, Gu X, Yang V. Doppler optical coherence tomography for energy seal evaluation and comparison to visual evaluation. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:1-14. [PMID: 32153148 PMCID: PMC7061233 DOI: 10.1117/1.jbo.25.3.035003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 02/20/2020] [Indexed: 06/10/2023]
Abstract
Laser energy sealing systems have attracted much attention over the past decade given the general shift in surgical paradigm toward less invasive surgical approaches. Given this, it is paramount to have an objective method with which the quality of energy seals can be evaluated. Current methodologies used for this purpose can be problematic in the evaluation of small vessel seals. A methodology employing Doppler optical coherence tomography (DOCT) for the evaluation of energy seals is introduced. Avian chorioallantoic membrane vessels were subjected to thulium laser irradiation and were then scanned via OCT. Outcomes were classified based on several markers, predominantly the presence or absence of flow postirradiation. Vessel diameter and general morphology were also taken into consideration. Vessels were classified into four groups: seal (29%), rupture (30%), partial seal (19%), and unaffected (22%). All vessels were also evaluated visually by a trained neurovascular surgeon, and these visually classified outcomes were compared with DOCT evaluated outcomes. It was found that whether the vessel was considered sealed or not sealed was dependent on the evaluation method (p = 0.01) where visual classification resulted in 18% more seals than DOCT classification. Further, the specificity of visual classification was found to be strongly dependent on the number of partial seals (p < 0.0001). DOCT has shown to be an indispensable method for the evaluation of energy seals not only solely due to its high velocity resolution but also due to valuable microscopic morphological insight regarding the biological mechanisms responsible for energy sealing.
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Affiliation(s)
- Andrew J. Marques
- Ryerson University, Bioengineering and Biophotonics Laboratory, Department of Electrical, Computer, and Biomedical Engineering, Toronto, Ontario, Canada
| | - Robnier Reyes
- Ryerson University, Bioengineering and Biophotonics Laboratory, Department of Electrical, Computer, and Biomedical Engineering, Toronto, Ontario, Canada
| | | | - Chaoliang Chen
- Ryerson University, Bioengineering and Biophotonics Laboratory, Department of Electrical, Computer, and Biomedical Engineering, Toronto, Ontario, Canada
| | - Joel Ramjist
- Ryerson University, Bioengineering and Biophotonics Laboratory, Department of Electrical, Computer, and Biomedical Engineering, Toronto, Ontario, Canada
| | - Xijia Gu
- Ryerson University, Department of Electrical, Computer, and Biomedical Engineering, Toronto, Ontario, Canada
| | - Victor Yang
- Ryerson University, Bioengineering and Biophotonics Laboratory, Department of Electrical, Computer, and Biomedical Engineering, Toronto, Ontario, Canada
- Sunnybrook Health and Sciences Center, Division of Neurosurgery, Toronto, Ontario, Canada
- University of Toronto, Division of Neurosurgery, Faculty of Medicine, Toronto Ontario, Canada
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3
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Guo S, Wei S, Lee S, Sheu M, Kang S, Kang JU. Intraoperative Speckle Variance Optical Coherence Tomography for Tissue Temperature Monitoring During Cutaneous Laser Therapy. IEEE JOURNAL OF TRANSLATIONAL ENGINEERING IN HEALTH AND MEDICINE 2019; 7:1800608. [PMID: 32309052 PMCID: PMC6788854 DOI: 10.1109/jtehm.2019.2943317] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 09/13/2019] [Accepted: 09/19/2019] [Indexed: 01/18/2023]
Abstract
Background: Tissue temperature monitoring during cutaneous laser therapy can lead to safer and more effective treatments. In this study, we investigate the use of speckle variance optical coherence tomography (svOCT) to monitor real-time temperature changes in the excised human skin tissue sample during laser irradiation. Methods: To accomplish this, we combined the pulse laser system with a reference-based svOCT system. To calibrate the svOCT, the ex-vivo human skin samples from three individuals with tissues collected from the arm, face, and back were heated with 1-degree increments. Additionally, linear regression was used to extract and evaluate the linear relationship between the temperature and normalized speckle variance value. Experiments were conducted on excised human skin sample to monitor the temperature change during laser therapy with a svOCT system. Thermal modeling of ex-vivo human skin was used to numerically simulate the laser-tissue interaction and estimate the thermal diffusion and peak temperature of the tissue during the laser treatment. Results and Conclusion: These results showed that normalized speckle variance had a linear relationship with the tissue temperature before the onset of tissue coagulation (52°) and we were able to measure the rapid increase of the tissue temperature during laser therapy. The result of the experiment is also in good agreement with the numerical simulation result that estimated the laser-induced peak temperature and thermal relaxation time.
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Affiliation(s)
- Shoujing Guo
- Electrical and Computer Engineering DepartmentJohns Hopkins UniversityBaltimoreMD21218USA
| | - Shuwen Wei
- Electrical and Computer Engineering DepartmentJohns Hopkins UniversityBaltimoreMD21218USA
| | - Soohyun Lee
- Electrical and Computer Engineering DepartmentJohns Hopkins UniversityBaltimoreMD21218USA
| | - Mary Sheu
- Department of DermatologyJohns Hopkins Medicine - Green Spring StationLuthervilleMD21093USA
| | - Sewon Kang
- Department of DermatologyThe Johns Hopkins HospitalBaltimoreMD21287USA
| | - Jin U. Kang
- Electrical and Computer Engineering DepartmentJohns Hopkins UniversityBaltimoreMD21218USA
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4
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Jansen SM, Almasian M, Wilk LS, de Bruin DM, van Berge Henegouwen MI, Strackee SD, Bloemen PR, Meijer SL, Gisbertz SS, van Leeuwen TG. Feasibility of Optical Coherence Tomography (OCT) for Intra-Operative Detection of Blood Flow during Gastric Tube Reconstruction. SENSORS (BASEL, SWITZERLAND) 2018; 18:E1331. [PMID: 29693606 PMCID: PMC5982600 DOI: 10.3390/s18051331] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 04/15/2018] [Accepted: 04/21/2018] [Indexed: 01/09/2023]
Abstract
In this study; an OCT-based intra-operative imaging method for blood flow detection during esophagectomy with gastric tube reconstruction is investigated. Change in perfusion of the gastric tube tissue can lead to ischemia; with a high morbidity and mortality as a result. Anastomotic leakage (incidence 5⁻20%) is one of the most severe complications after esophagectomy with gastric tube reconstruction. Optical imaging techniques provide for minimal-invasive and real-time visualization tools that can be used in intraoperative settings. By implementing an optical technique for blood flow detection during surgery; perfusion can be imaged and quantified and; if needed; perfusion can be improved by either a surgical intervention or the administration of medication. The feasibility of imaging gastric microcirculation in vivo using optical coherence tomography (OCT) during surgery of patients with esophageal cancer by visualizing blood flow based on the speckle contrast from M-mode OCT images is studied. The percentage of pixels exhibiting a speckle contrast value indicative of flow was quantified to serve as an objective parameter to assess blood flow at 4 locations on the reconstructed gastric tube. Here; it was shown that OCT can be used for direct blood flow imaging during surgery and may therefore aid in improving surgical outcomes for patients.
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Affiliation(s)
- Sanne M Jansen
- Department of Biomedical Engineering & Physics, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
- Department of Plastic, Reconstructive & Hand Surgery, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Mitra Almasian
- Department of Biomedical Engineering & Physics, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Leah S Wilk
- Department of Biomedical Engineering & Physics, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Daniel M de Bruin
- Department of Biomedical Engineering & Physics, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Mark I van Berge Henegouwen
- Department of Surgery, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Simon D Strackee
- Department of Plastic, Reconstructive & Hand Surgery, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Paul R Bloemen
- Department of Biomedical Engineering & Physics, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Sybren L Meijer
- Department of Pathology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Suzanne S Gisbertz
- Department of Surgery, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Ton G van Leeuwen
- Department of Biomedical Engineering & Physics, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
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5
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Shu X, Beckmann L, Zhang HF. Visible-light optical coherence tomography: a review. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-14. [PMID: 29218923 PMCID: PMC5745673 DOI: 10.1117/1.jbo.22.12.121707] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 11/13/2017] [Indexed: 05/03/2023]
Abstract
Visible-light optical coherence tomography (vis-OCT) is an emerging imaging modality, providing new capabilities in both anatomical and functional imaging of biological tissue. It relies on visible light illumination, whereas most commercial and investigational OCTs use near-infrared light. As a result, vis-OCT requires different considerations in engineering design and implementation but brings unique potential benefits to both fundamental research and clinical care of several diseases. Here, we intend to provide a summary of the development of vis-OCT and its demonstrated applications. We also provide perspectives on future technology improvement and applications.
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Affiliation(s)
- Xiao Shu
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois, United States
| | - Lisa Beckmann
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois, United States
| | - Hao F. Zhang
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois, United States
- Northwestern University, Department of Ophthalmology, Chicago, Illinois, United States
- Address all correspondence to: Hao F. Zhang, E-mail:
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6
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Grishina OA, Wang S, Larina IV. Speckle variance optical coherence tomography of blood flow in the beating mouse embryonic heart. JOURNAL OF BIOPHOTONICS 2017; 10:735-743. [PMID: 28417585 PMCID: PMC5565627 DOI: 10.1002/jbio.201600293] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 01/25/2017] [Accepted: 01/31/2017] [Indexed: 05/19/2023]
Abstract
Efficient separation of blood and cardiac wall in the beating embryonic heart is essential and critical for experiment-based computational modelling and analysis of early-stage cardiac biomechanics. Although speckle variance optical coherence tomography (SV-OCT) relying on calculation of intensity variance over consecutively acquired frames is a powerful approach for segmentation of fluid flow from static tissue, application of this method in the beating embryonic heart remains challenging because moving structures generate SV signal indistinguishable from the blood. Here, we demonstrate a modified four-dimensional SV-OCT approach that effectively separates the blood flow from the dynamic heart wall in the beating mouse embryonic heart. The method takes advantage of the periodic motion of the cardiac wall and is based on calculation of the SV signal over the frames corresponding to the same phase of the heartbeat cycle. Through comparison with Doppler OCT imaging, we validate this speckle-based approach and show advantages in its insensitiveness to the flow direction and velocity as well as reduced influence from the heart wall movement. This approach has a potential in variety of applications relying on visualization and segmentation of blood flow in periodically moving structures, such as mechanical simulation studies and finite element modelling. Picture: Four-dimensional speckle variance OCT imaging shows the blood flow inside the beating heart of an E8.5 mouse embryo.
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Affiliation(s)
| | | | - Irina V. Larina
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030, USA
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7
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Liu X, Zaki F, Wang Y, Huang Q, Mei X, Wang J. Secure fingerprint identification based on structural and microangiographic optical coherence tomography. APPLIED OPTICS 2017; 56:2255-2259. [PMID: 28375315 DOI: 10.1364/ao.56.002255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Optical coherence tomography (OCT) allows noncontact acquisition of fingerprints and hence is a highly promising technology in the field of biometrics. OCT can be used to acquire both structural and microangiographic images of fingerprints. Microangiographic OCT derives its contrast from the blood flow in the vasculature of viable skin tissue, and microangiographic fingerprint imaging is inherently immune to fake fingerprint attack. Therefore, dual-modality (structural and microangiographic) OCT imaging of fingerprints will enable more secure acquisition of biometric data, which has not been investigated before. Our study on fingerprint identification based on structural and microangiographic OCT imaging is, we believe, highly innovative. In this study, we performed OCT imaging study for fingerprint acquisition, and demonstrated the capability of dual-modality OCT imaging for the identification of fake fingerprints.
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8
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Wang Y, Wang Y, Akansu A, Belfield KD, Hubbi B, Liu X. Robust motion tracking based on adaptive speckle decorrelation analysis of OCT signal. BIOMEDICAL OPTICS EXPRESS 2015; 6:4302-16. [PMID: 26600996 PMCID: PMC4646540 DOI: 10.1364/boe.6.004302] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 09/22/2015] [Accepted: 09/24/2015] [Indexed: 05/19/2023]
Abstract
Speckle decorrelation analysis of optical coherence tomography (OCT) signal has been used in motion tracking. In our previous study, we demonstrated that cross-correlation coefficient (XCC) between Ascans had an explicit functional dependency on the magnitude of lateral displacement (δx). In this study, we evaluated the sensitivity of speckle motion tracking using the derivative of function XCC(δx) on variable δx. We demonstrated the magnitude of the derivative can be maximized. In other words, the sensitivity of OCT speckle tracking can be optimized by using signals with appropriate amount of decorrelation for XCC calculation. Based on this finding, we developed an adaptive speckle decorrelation analysis strategy to achieve motion tracking with optimized sensitivity. Briefly, we used subsequently acquired Ascans and Ascans obtained with larger time intervals to obtain multiple values of XCC and chose the XCC value that maximized motion tracking sensitivity for displacement calculation. Instantaneous motion speed can be calculated by dividing the obtained displacement with time interval between Ascans involved in XCC calculation. We implemented the above-described algorithm in real-time using graphic processing unit (GPU) and demonstrated its effectiveness in reconstructing distortion-free OCT images using data obtained from a manually scanned OCT probe. The adaptive speckle tracking method was validated in manually scanned OCT imaging, on phantom as well as in vivo skin tissue.
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Affiliation(s)
- Yuewen Wang
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ, 07102, USA
| | - Yahui Wang
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ, 07102, USA
| | - Ali Akansu
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ, 07102, USA
| | - Kevin D. Belfield
- College of Science and Liberal Arts, New Jersey Institute of Technology, Newark, NJ, 07102, USA
| | - Basil Hubbi
- Department of Radiology, New Jersey Medical School, Newark, NJ, 07103, USA
| | - Xuan Liu
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ, 07102, USA
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9
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Lozzi A, Agrawal A, Boretsky A, Welle CG, Hammer DX. Image quality metrics for optical coherence angiography. BIOMEDICAL OPTICS EXPRESS 2015; 6:2435-2447. [PMID: 26203372 PMCID: PMC4505700 DOI: 10.1364/boe.6.002435] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 05/13/2015] [Accepted: 06/09/2015] [Indexed: 05/20/2023]
Abstract
We characterized image quality in optical coherence angiography (OCA) en face planes of mouse cortical capillary network in terms of signal-to-noise ratio (SNR) and Weber contrast (Wc) through a novel mask-based segmentation method. The method was used to compare two adjacent B-scan processing algorithms, (1) average absolute difference (AAD) and (2) standard deviation (SD), while varying the number of lateral cross-sections acquired (also known as the gate length, N). AAD and SD are identical at N = 2 and exhibited similar image quality for N<10. However, AAD is relatively less susceptible to bulk tissue motion artifact than SD. SNR and Wc were 15% and 35% higher for AAD from N = 25 to 100. In addition data sets were acquired with two objective lenses with different magnifications to quantify the effect of lateral resolution on fine capillary detection. The lower power objective yielded a significant mean broadening of 17% in Full Width Half Maximum (FWHM) diameter. These results may guide study and device designs for OCA capillary and blood flow quantification.
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Affiliation(s)
- Andrea Lozzi
- Center for Devices and Radiological Health, Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring MD 20993, USA
| | - Anant Agrawal
- Center for Devices and Radiological Health, Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring MD 20993, USA
| | - Adam Boretsky
- Center for Devices and Radiological Health, Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring MD 20993, USA
| | - Cristin G. Welle
- Center for Devices and Radiological Health, Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring MD 20993, USA
| | - Daniel X. Hammer
- Center for Devices and Radiological Health, Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring MD 20993, USA
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10
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Chong SP, Merkle CW, Leahy C, Radhakrishnan H, Srinivasan VJ. Quantitative microvascular hemoglobin mapping using visible light spectroscopic Optical Coherence Tomography. BIOMEDICAL OPTICS EXPRESS 2015; 6:1429-50. [PMID: 25909026 PMCID: PMC4399681 DOI: 10.1364/boe.6.001429] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 02/19/2015] [Accepted: 03/14/2015] [Indexed: 05/18/2023]
Abstract
Quantification of chromophore concentrations in reflectance mode remains a major challenge for biomedical optics. Spectroscopic Optical Coherence Tomography (SOCT) provides depth-resolved spectroscopic information necessary for quantitative analysis of chromophores, like hemoglobin, but conventional SOCT analysis methods are applicable only to well-defined specular reflections, which may be absent in highly scattering biological tissue. Here, by fitting of the dynamic scattering signal spectrum in the OCT angiogram using a forward model of light propagation, we quantitatively determine hemoglobin concentrations directly. Importantly, this methodology enables mapping of both oxygen saturation and total hemoglobin concentration, or alternatively, oxyhemoglobin and deoxyhemoglobin concentration, simultaneously. Quantification was verified by ex vivo blood measurements at various pO2 and hematocrit levels. Imaging results from the rodent brain and retina are presented. Confounds including noise and scattering, as well as potential clinical applications, are discussed.
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11
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Liu X, Kirby M, Zhao F. Motion analysis and removal in intensity variation based OCT angiography. BIOMEDICAL OPTICS EXPRESS 2014; 5:3833-47. [PMID: 25426314 PMCID: PMC4242021 DOI: 10.1364/boe.5.003833] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 09/18/2014] [Accepted: 09/19/2014] [Indexed: 05/18/2023]
Abstract
In this work, we investigated how bulk motion degraded the quality of optical coherence tomography (OCT) angiography that was obtained through calculating interframe signal variation, i.e., interframe signal variation based optical coherence angiography (isvOCA). We demonstrated theoretically and experimentally that the spatial average of isvOCA signal had an explicit functional dependency on bulk motion. Our result suggested that the bulk motion could lead to an increased background in angiography image. Based on our motion analysis, we proposed to reduce image artifact induced by transient bulk motion in isvOCA through adaptive thresholding. The motion artifact reduced angiography was demonstrated in a 1.3μm spectral domain OCT system. We implemented signal processing using graphic processing unit for real-time imaging and conducted in vivo microvasculature imaging on human skin. Our results clearly showed that the adaptive thresholding method was highly effective in the motion artifact removal for OCT angiography.
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Affiliation(s)
- Xuan Liu
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, 323 Dr Martin Luther King Jr Blvd, Newark, NJ USA
| | - Mitchell Kirby
- Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Dr., Houghton, MI USA
| | - Feng Zhao
- Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Dr., Houghton, MI USA
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12
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The chicken chorioallantoic membrane model in biology, medicine and bioengineering. Angiogenesis 2014; 17:779-804. [PMID: 25138280 DOI: 10.1007/s10456-014-9440-7] [Citation(s) in RCA: 289] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 08/13/2014] [Indexed: 01/16/2023]
Abstract
The chicken chorioallantoic membrane (CAM) is a simple, highly vascularized extraembryonic membrane, which performs multiple functions during embryonic development, including but not restricted to gas exchange. Over the last two decades, interest in the CAM as a robust experimental platform to study blood vessels has been shared by specialists working in bioengineering, development, morphology, biochemistry, transplant biology, cancer research and drug development. The tissue composition and accessibility of the CAM for experimental manipulation, makes it an attractive preclinical in vivo model for drug screening and/or for studies of vascular growth. In this article we provide a detailed review of the use of the CAM to study vascular biology and response of blood vessels to a variety of agonists. We also present distinct cultivation protocols discussing their advantages and limitations and provide a summarized update on the use of the CAM in vascular imaging, drug delivery, pharmacokinetics and toxicology.
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13
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Nowak-Sliwinska P, van den Bergh H, Sickenberg M, Koh AHC. Photodynamic therapy for polypoidal choroidal vasculopathy. Prog Retin Eye Res 2013; 37:182-99. [PMID: 24140257 DOI: 10.1016/j.preteyeres.2013.09.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 09/23/2013] [Accepted: 09/27/2013] [Indexed: 01/05/2023]
Affiliation(s)
- Patrycja Nowak-Sliwinska
- Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland; University Hospital (CHUV), Lausanne, Switzerland.
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14
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Daly SM, Silien C, Leahy MJ. Feasibility of capillary velocity assessment by statistical means using dual-beam spectral-domain Optical Coherence Tomography: a preliminary study. JOURNAL OF BIOPHOTONICS 2013; 6:718-732. [PMID: 23303589 DOI: 10.1002/jbio.201200203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 11/25/2012] [Accepted: 12/12/2012] [Indexed: 06/01/2023]
Abstract
The assessment of vascular dynamics has been shown to yield both qualitative and quantitative metrics and thus play a pivotal role in the diagnosis and prognosis of various diseases, which may manifest as microcirculatory irregularities. Optical Coherence Tomography (OCT) is an established imaging modality which utilises the principle of optical interferometry to distinguish between spatial changes in refractive index and thus formulate a multi-dimensional representation of a specimen in vivo. Nonetheless, difficulties remain in obtaining accurate data (morphological and/or transient) in an environment which is subject to such large biological variability. In an effort to address the issue of angular dependence as with Doppler based analysis, a dual-beam Spectral-domain OCT system for quasi-simultaneous specimen scanning is described. A statistical based method of phase correlation is outlined which is capable of quantifying velocity values in addition to the ability to discern bidirectionality, without the necessity of angular computation.
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Affiliation(s)
- Susan M Daly
- Dept. Physics and Energy, University of Limerick, Ireland.
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15
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Daly SM, Leahy MJ. 'Go with the flow ': a review of methods and advancements in blood flow imaging. JOURNAL OF BIOPHOTONICS 2013; 6:217-55. [PMID: 22711377 DOI: 10.1002/jbio.201200071] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 05/22/2012] [Accepted: 05/23/2012] [Indexed: 05/25/2023]
Abstract
Physics has delivered extraordinary developments in almost every facet of modern life. From the humble thermometer and stethoscope to X-Ray, CT, MRI, ultrasound, PET and radiotherapy, our health has been transformed by these advances yielding both morphological and functional metrics. Recently high resolution label-free imaging of the microcirculation at clinically relevant depths has become available in the research domain. In this paper, we present a comprehensive review on current imaging techniques, state-of-the-art advancements and applications, and general perspectives on the prospects for these modalities in the clinical realm.
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Affiliation(s)
- Susan M Daly
- Biophotonics Research Facility, Department of Physics & Energy, University of Limerick, Ireland.
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Liu X, Huang Y, Ramella-Roman JC, Mathews SA, Kang JU. Quantitative transverse flow measurement using optical coherence tomography speckle decorrelation analysis. OPTICS LETTERS 2013; 38:805-7. [PMID: 23455305 PMCID: PMC4102610 DOI: 10.1364/ol.38.000805] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We propose an inter-Ascan speckle decorrelation based method that can quantitatively assess blood flow normal to the direction of the optical coherence tomography imaging beam. To validate this method, we performed a systematic study using both phantom and in vivo animal models. Results show that our speckle analysis method can accurately extract transverse flow speed with high spatial and temporal resolution.
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Affiliation(s)
- Xuan Liu
- Department of Electrical and Computer Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
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17
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Liu X, Ramella-Roman JC, Huang Y, Guo Y, Kang JU. Robust spectral-domain optical coherence tomography speckle model and its cross-correlation coefficient analysis. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2013; 30:51-59. [PMID: 23456001 PMCID: PMC3615453 DOI: 10.1364/josaa.30.000051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
In this study, we propose a generic speckle simulation for optical coherence tomography (OCT) signal, by convolving the point-spread function (PSF) of the OCT system with the numerically synthesized random sample field. We validate our model and use the simulation method to study the statistical properties of cross-correlation coefficients between A-scans, which have been recently applied in transverse motion analysis by our group. The results of simulation show that oversampling is essential for accurate motion tracking; exponential decay of OCT signal leads to an underestimate of motion that can be corrected; lateral heterogeneity of sample leads to an overestimate of motion for a few pixels corresponding to the structural boundary.
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Affiliation(s)
- Xuan Liu
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA.
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18
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Kang JU, Huang Y, Zhang K, Ibrahim Z, Cha J, Lee WPA, Brandacher G, Gehlbach PL. Real-time three-dimensional Fourier-domain optical coherence tomography video image guided microsurgeries. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:081403-1. [PMID: 23224164 PMCID: PMC3381017 DOI: 10.1117/1.jbo.17.8.081403] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2011] [Revised: 03/03/2012] [Accepted: 03/12/2012] [Indexed: 05/20/2023]
Abstract
The authors describe the development of an ultrafast three-dimensional (3D) optical coherence tomography (OCT) imaging system that provides real-time intraoperative video images of the surgical site to assist surgeons during microsurgical procedures. This system is based on a full-range complex conjugate free Fourier-domain OCT (FD-OCT). The system was built in a CPU-GPU heterogeneous computing architecture capable of video OCT image processing. The system displays at a maximum speed of 10 volume/s for an image volume size of 160 × 80 × 1024(X × Y × Z) pixels. We have used this system to visualize and guide two prototypical microsurgical maneuvers: microvascular anastomosis of the rat femoral artery and ultramicrovascular isolation of the retinal arterioles of the bovine retina. Our preliminary experiments using 3D-OCT-guided microvascular anastomosis showed optimal visualization of the rat femoral artery (diameter<0.8 mm), instruments, and suture material. Real-time intraoperative guidance helped facilitate precise suture placement due to optimized views of the vessel wall during anastomosis. Using the bovine retina as a model system, we have performed "ultra microvascular" feasibility studies by guiding handheld surgical micro-instruments to isolate retinal arterioles (diameter ~0.1 mm). Isolation of the microvessels was confirmed by successfully passing a suture beneath the vessel in the 3D imaging environment.
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Affiliation(s)
- Jin U Kang
- Johns Hopkins University, Department of Electrical and Computer Engineering, 3400 N. Charles Street, Baltimore, MD 21218, USA.
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19
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Lee KKC, Mariampillai A, Yu JXZ, Cadotte DW, Wilson BC, Standish BA, Yang VXD. Real-time speckle variance swept-source optical coherence tomography using a graphics processing unit. BIOMEDICAL OPTICS EXPRESS 2012; 3:1557-64. [PMID: 22808428 PMCID: PMC3395481 DOI: 10.1364/boe.3.001557] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Revised: 05/30/2012] [Accepted: 06/05/2012] [Indexed: 05/20/2023]
Abstract
Advances in swept source laser technology continues to increase the imaging speed of swept-source optical coherence tomography (SS-OCT) systems. These fast imaging speeds are ideal for microvascular detection schemes, such as speckle variance (SV), where interframe motion can cause severe imaging artifacts and loss of vascular contrast. However, full utilization of the laser scan speed has been hindered by the computationally intensive signal processing required by SS-OCT and SV calculations. Using a commercial graphics processing unit that has been optimized for parallel data processing, we report a complete high-speed SS-OCT platform capable of real-time data acquisition, processing, display, and saving at 108,000 lines per second. Subpixel image registration of structural images was performed in real-time prior to SV calculations in order to reduce decorrelation from stationary structures induced by the bulk tissue motion. The viability of the system was successfully demonstrated in a high bulk tissue motion scenario of human fingernail root imaging where SV images (512 × 512 pixels, n = 4) were displayed at 54 frames per second.
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Affiliation(s)
- Kenneth K. C. Lee
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, Canada
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada
- These authors contributed equally to this work
| | - Adrian Mariampillai
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada
- These authors contributed equally to this work
| | - Joe X. Z. Yu
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada
| | - David W. Cadotte
- Division of Neurosurgery, Toronto Western Hospital, Toronto, Ontario, Canada
- Instite of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Krembil Neuroscience Centre, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Brian C. Wilson
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Beau A. Standish
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada
| | - Victor X. D. Yang
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, Canada
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada
- Department of Medical Imaging, St. Michael’s Hospital, Toronto, Ontario, Canada
- Division of Neurosurgery, St. Michael’s Hospital, Toronto, Ontario, Canada
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20
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Gregg CL, Butcher JT. Quantitative in vivo imaging of embryonic development: opportunities and challenges. Differentiation 2012; 84:149-62. [PMID: 22695188 DOI: 10.1016/j.diff.2012.05.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 05/03/2012] [Accepted: 05/04/2012] [Indexed: 10/28/2022]
Abstract
Animal models are critically important for a mechanistic understanding of embryonic morphogenesis. For decades, visualizing these rapid and complex multidimensional events has relied on projection images and thin section reconstructions. While much insight has been gained, fixed tissue specimens offer limited information on dynamic processes that are essential for tissue assembly and organ patterning. Quantitative imaging is required to unlock the important basic science and clinically relevant secrets that remain hidden. Recent advances in live imaging technology have enabled quantitative longitudinal analysis of embryonic morphogenesis at multiple length and time scales. Four different imaging modalities are currently being used to monitor embryonic morphogenesis: optical, ultrasound, magnetic resonance imaging (MRI), and micro-computed tomography (micro-CT). Each has its advantages and limitations with respect to spatial resolution, depth of field, scanning speed, and tissue contrast. In addition, new processing tools have been developed to enhance live imaging capabilities. In this review, we analyze each type of imaging source and its use in quantitative study of embryonic morphogenesis in small animal models. We describe the physics behind their function, identify some examples in which the modality has revealed new quantitative insights, and then conclude with a discussion of new research directions with live imaging.
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Affiliation(s)
- Chelsea L Gregg
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA
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