1
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Tian Y, Zhang M, Man H, Wu C, Wang Y, Kong L, Liu J. Study of ischemic progression in different intestinal tissue layers during acute intestinal ischemia using swept-source optical coherence tomography angiography. JOURNAL OF BIOPHOTONICS 2024; 17:e202300382. [PMID: 38247043 DOI: 10.1002/jbio.202300382] [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: 09/14/2023] [Revised: 01/04/2024] [Accepted: 01/04/2024] [Indexed: 01/23/2024]
Abstract
In acute intestinal ischemia, the progression of ischemia varies across different layers of intestinal tissue. We established a mouse model and used swept-source optical coherence tomography (OCT) to observe the intestinal ischemic process longitudinally in different tissue layers. Employing a method that combines asymmetric gradient filtering with adaptive weighting, we eliminated the vessel trailing phenomenon in OCT angiograms, reducing the confounding effects of superficial vessels on the imaging of deeper vasculature. We quantitatively assessed changes in vascular perfusion density (VPD), vessel length, and vessel average diameter across various intestinal layers. Our results showed a significant reduction in VPD in all layers during ischemia. The mucosa layer experienced the most significant impact, primarily due to disrupted capillary blood flow, followed by the submucosa layer, where vascular constriction or decreased velocity was the primary factor.
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Affiliation(s)
- Yu Tian
- Department of Surgical, Hebei Medical University, Shijiazhuang, Hebei Province, China
| | - Mingshuo Zhang
- Hebei North University, Zhangjiakou, China
- Department of Hand & Foot Surgery, First Hospital of Qinhuangdao, Qinhuangdao, China
| | - Hongbo Man
- Hebei North University, Zhangjiakou, China
- Department of Hand & Foot Surgery, First Hospital of Qinhuangdao, Qinhuangdao, China
| | - Chunnan Wu
- Department of General Surgery, First Hospital of Qinhuangdao, Qinhuangdao, China
| | - Yimin Wang
- Department of Surgical, Hebei Medical University, Shijiazhuang, Hebei Province, China
- Department of General Surgery, First Hospital of Qinhuangdao, Qinhuangdao, China
| | - Linghui Kong
- School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao, China
| | - Jian Liu
- School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao, China
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2
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Zhang W, Zhou H, Tao Y, Zhu F, He B, Liu N, Chen J, Xue P. Size correction and deep image optimization in optical coherence tomography angiography with structural image-assisted common parts extraction method. JOURNAL OF BIOPHOTONICS 2024; 17:e202300259. [PMID: 37755063 DOI: 10.1002/jbio.202300259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 09/20/2023] [Accepted: 09/25/2023] [Indexed: 09/28/2023]
Abstract
Tail artifact elimination is essential in optical coherence tomography angiography (OCTA) for the artifacts will prevent the reconstruction of the 3D vessel image. The tail artifacts of superficial vessels obscure the deep vascular signals and cause the signals at different depths to mix with each other. Most tail artifact elimination methods can shorten the tails but have difficulty in determining the lower boundary of the vessels. In this letter, we introduce a technique to extract vascular signals with more accurate vascular boundaries. With the help of structural image, our method can reconstruct the 3D image of the vascular network more precisely and perform better in deep areas. The images of vessels of palm are used to compare our new technique with previous common parts extraction method experimentally. The results show that our method removes the tail artifacts more thoroughly and has a significant advantage in imaging deep vessels.
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Affiliation(s)
- Wenxin Zhang
- College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing, China
- State Key Laboratory of Low-dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, China
| | - Hong Zhou
- College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing, China
| | - Yuxiu Tao
- College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing, China
| | - Fu Zhu
- College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing, China
| | - Bin He
- State Key Laboratory of Low-dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, China
| | - Ning Liu
- College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing, China
| | - Junyi Chen
- Jiangsu Kunpeng Shengteng Ecological Innovation Center, Nanjing, Jiangsu, China
| | - Ping Xue
- State Key Laboratory of Low-dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, China
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3
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Simoncic U, Milanic M. Tail Artifact Removal via Transmittance Effect Subtraction in Optical Coherence Tail Artifact Images. SENSORS (BASEL, SWITZERLAND) 2023; 23:9312. [PMID: 38067685 PMCID: PMC10708777 DOI: 10.3390/s23239312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/14/2023] [Accepted: 11/20/2023] [Indexed: 12/18/2023]
Abstract
Optical Coherence Tomography Angiography (OCTA) has revolutionized non-invasive, high-resolution imaging of blood vessels. However, the challenge of tail artifacts in OCTA images persists. In response, we present the Tail Artifact Removal via Transmittance Effect Subtraction (TAR-TES) algorithm that effectively mitigates these artifacts. Through a simple physics-based model, the TAR-TES accounts for variations in transmittance within the shallow layers with the vasculature, resulting in the removal of tail artifacts in deeper layers after the vessel. Comparative evaluations with alternative correction methods demonstrate that TAR-TES excels in eliminating these artifacts while preserving the essential integrity of vasculature images. Crucially, the success of the TAR-TES is closely linked to the precise adjustment of a weight constant, underlining the significance of individual dataset parameter optimization. In conclusion, TAR-TES emerges as a powerful tool for enhancing OCTA image quality and reliability in both clinical and research settings, promising to reshape the way we visualize and analyze intricate vascular networks within biological tissues. Further validation across diverse datasets is essential to unlock the full potential of this physics-based solution.
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Affiliation(s)
- Urban Simoncic
- Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia;
- Jozef Stefan Institute, 1000 Ljubljana, Slovenia
| | - Matija Milanic
- Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia;
- Jozef Stefan Institute, 1000 Ljubljana, Slovenia
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4
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Puyo L, Pfäffle C, Spahr H, Franke J, Bublitz D, Hillmann D, Hüttmann G. Diffuse-illumination holographic optical coherence tomography. OPTICS EXPRESS 2023; 31:33500-33517. [PMID: 37859131 DOI: 10.1364/oe.498654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 09/11/2023] [Indexed: 10/21/2023]
Abstract
Holographic optical coherence tomography (OCT) is a powerful imaging technique, but its ability to reveal low-reflectivity features is limited. In this study, we performed holographic OCT by incoherently averaging volumes with changing diffuse illumination of numerical aperture (NA) equal to the detection NA. While the reduction of speckle from singly scattered light is only modest, we discovered that speckle from multiply scattered light can be arbitrarily reduced, resulting in substantial improvements in image quality. This technique also offers the advantage of suppressing noises arising from spatial coherence, and can be implemented with a partially spatially incoherent light source for further mitigation of multiple scattering. Finally, we show that although holographic reconstruction capabilities are increasingly lost with decreasing spatial coherence, they can be retained over an axial range sufficient to standard OCT applications.
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5
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Zhou J, Li Y, Tang J. Adaptive dynamic analysis-based optical coherence tomography angiography for blood vessel projection artifact suppression. BIOMEDICAL OPTICS EXPRESS 2023; 14:477-488. [PMID: 36698660 PMCID: PMC9842011 DOI: 10.1364/boe.469891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 12/11/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
Optical coherence tomography angiography (OCTA) for blood vessel 3-D structure imaging suffers from blood vessel projection artifacts/tail artifacts when using a long decorrelation time (e.g., repeat B-scan acquisition in regular OCTA) or loss of micro vessel signal when using a short decorrelation time. In this work, we developed an adaptive first-order field autocorrelation function (g1) analysis-based technique to suppress the projection artifacts under macro vessels while enhancing the dynamic signal of micro vessels. The proposed method is based on the differences of the decorrelation rate and the phase variations of g1 between the vessel voxels and the artifacts regions. A short or long decorrelation time was applied to obtain the dynamic index of the projection artifacts region or the blood vessel region, respectively. Compared to the slab subtraction-based post-image processing-based techniques, the proposed approach addresses this problem on a physical basis and shows the ability to suppress the projection artifacts while enhancing the detection of the micro vessels.
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Affiliation(s)
- Junxiong Zhou
- Guangdong Provincial Key Laboratory of Advanced Biomaterials, Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
- Contributed equally
| | - Yuntao Li
- Guangdong Provincial Key Laboratory of Advanced Biomaterials, Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
- Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115, USA
- Contributed equally
| | - Jianbo Tang
- Guangdong Provincial Key Laboratory of Advanced Biomaterials, Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
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6
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Zhang W, He B, Wu Y, Tao Y, Zhu F, Cai W, Liu N, Zhao Q, Xue P. Tail artifacts removal of three-dimensional optical coherence tomography angiography with common parts extraction method. JOURNAL OF BIOPHOTONICS 2022; 15:e202200155. [PMID: 36328058 DOI: 10.1002/jbio.202200155] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 07/11/2022] [Accepted: 08/02/2022] [Indexed: 06/16/2023]
Abstract
In optical coherence tomography angiography (OCTA), each blood vessel has a tail artifact. These tails of superficial vessels will shadow underlying the deep vascular images and make it difficult to reconstruct the three-dimensional (3D) image of the vessels. As 3D structure can provide much more information than two-dimensional (2D) images, it is important to develop a method to remove the artifacts. In this letter, we introduce an image processing technique based on common parts extraction to remove the artifacts. With the help of subtraction operation and erode operation, our method can reconstruct the 3D image of vascular network by extracting the common parts of adjacent B-Scan OCTA images. Vessels of palm are used as samples to experimentally demonstrate our technique. In the 3D image, we can see the interesting phenomenon that the ends of the blood vessels which close to the surface of the skin point toward the surface.
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Affiliation(s)
- Wenxin Zhang
- College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing, China
- State Key Laboratory of Low-dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, China
| | - Bin He
- State Key Laboratory of Low-dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, China
| | - Yangkang Wu
- College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing, China
| | - Yuxiu Tao
- College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing, China
| | - Fu Zhu
- College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing, China
| | - Wenchao Cai
- College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing, China
| | - Ning Liu
- College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing, China
| | - Qiang Zhao
- College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing, China
| | - Ping Xue
- State Key Laboratory of Low-dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, China
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7
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Stefan S, Lee J. Deep learning toolbox for automated enhancement, segmentation, and graphing of cortical optical coherence tomography microangiograms. BIOMEDICAL OPTICS EXPRESS 2020; 11:7325-7342. [PMID: 33409000 PMCID: PMC7747889 DOI: 10.1364/boe.405763] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 05/03/2023]
Abstract
Optical coherence tomography angiography (OCTA) is becoming increasingly popular for neuroscientific study, but it remains challenging to objectively quantify angioarchitectural properties from 3D OCTA images. This is mainly due to projection artifacts or "tails" underneath vessels caused by multiple-scattering, as well as the relatively low signal-to-noise ratio compared to fluorescence-based imaging modalities. Here, we propose a set of deep learning approaches based on convolutional neural networks (CNNs) to automated enhancement, segmentation and gap-correction of OCTA images, especially of those obtained from the rodent cortex. Additionally, we present a strategy for skeletonizing the segmented OCTA and extracting the underlying vascular graph, which enables the quantitative assessment of various angioarchitectural properties, including individual vessel lengths and tortuosity. These tools, including the trained CNNs, are made publicly available as a user-friendly toolbox for researchers to input their OCTA images and subsequently receive the underlying vascular network graph with the associated angioarchitectural properties.
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Affiliation(s)
- Sabina Stefan
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI 02912, USA
| | - Jonghwan Lee
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI 02912, USA
- Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA
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8
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Choi WJ, Paulson B, Yu S, Wang RK, Kim JK. Mean-Subtraction Method for De-shadowing of Tail Artifacts in Cerebral OCTA Images: A Proof of Concept. MATERIALS 2020; 13:ma13092024. [PMID: 32357466 PMCID: PMC7254351 DOI: 10.3390/ma13092024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 01/25/2023]
Abstract
When imaging brain vasculature with optical coherence tomography angiography (OCTA), volumetric analysis of cortical vascular networks in OCTA datasets is frequently challenging due to the presence of artifacts, which appear as multiple-scattering tails beneath superficial large vessels in OCTA images. These tails shadow underlying small vessels, making the assessment of vascular morphology in the deep cortex difficult. In this work, we introduce an image processing technique based on mean subtraction of the depth profile that can effectively reduce these tails to better reveal small hidden vessels compared to the current tail removal approach. With the improved vascular image quality, we demonstrate that this simple method can provide better visualization of three-dimensional vascular network topology for quantitative cerebrovascular studies.
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Affiliation(s)
- Woo June Choi
- School of Electrical and Electronics Engineering, Chung-Ang University, Seoul 06974, Korea; (W.J.C.); (S.Y.)
| | - Bjorn Paulson
- Biomedical Engineering Research Center, Asan Institute for Life Science, Asan Medical Center, Seoul 05505, Korea;
| | - Sungwook Yu
- School of Electrical and Electronics Engineering, Chung-Ang University, Seoul 06974, Korea; (W.J.C.); (S.Y.)
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA;
| | - Jun Ki Kim
- Biomedical Engineering Research Center, Asan Institute for Life Science, Asan Medical Center, Seoul 05505, Korea;
- Department of Convergence Medicine, University of Ulsan College of Medicine, Seoul 05505, Korea
- Correspondence: ; Tel.: +82-2-3010-8619
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9
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Huang L, Fu Y, Chen R, Yang S, Qiu H, Wu X, Zhao S, Gu Y, Li P. SNR-Adaptive OCT Angiography Enabled by Statistical Characterization of Intensity and Decorrelation With Multi-Variate Time Series Model. IEEE TRANSACTIONS ON MEDICAL IMAGING 2019; 38:2695-2704. [PMID: 30990423 DOI: 10.1109/tmi.2019.2910871] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
In OCT angiography (OCTA), decorrelation computation has been widely used as a local motion index to identify dynamic flow from static tissues, but its dependence on SNR severely degrades the vascular visibility, particularly in low-SNR regions. To mathematically characterize the decorrelation-SNR dependence of OCT signals, we developed a multi-variate time series (MVTS) model. Based on the model, we derived a universal asymptotic linear relation of decorrelation to inverse SNR (iSNR), with the variance in static and noise regions determined by the average kernel size. Accordingly, with the population distribution of static and noise voxels being explicitly calculated in the iSNR and decorrelation (ID) space, a linear classifier is developed by removing static and noise voxels at all SNR, to generate a SNR-adaptive OCTA, termed as ID-OCTA. Then, flow phantom and human skin experiments were performed to validate the proposed ID-OCTA. Both qualitative and quantitative assessments demonstrated that the ID-OCTA offers a superior visibility of blood vessels, particularly in the deep layer. Finally, the implications of this work on both system design and hemodynamic quantification are further discussed.
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10
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Tang J, Erdener SE, Sunil S, Boas DA. Normalized field autocorrelation function-based optical coherence tomography three-dimensional angiography. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-8. [PMID: 30868803 PMCID: PMC6414735 DOI: 10.1117/1.jbo.24.3.036005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 02/06/2019] [Indexed: 05/02/2023]
Abstract
Optical coherence tomography angiography (OCTA) has been widely used for en face visualization of the microvasculature, but is challenged for real three-dimensional (3-D) topologic imaging due to the "tail" artifacts that appear below large vessels. Further, OCTA is generally incapable of differentiating descending arterioles from ascending venules. We introduce a normalized field autocorrelation function-based OCTA (g1-OCTA), which minimizes the tail artifacts and is capable of distinguishing penetrating arterioles from venules in the 3-D image. g1 ( τ ) is calculated from repeated optical coherence tomography (OCT) acquisitions for each spatial location. The decay amplitude of g1 ( τ ) is retrieved to represent the dynamics for each voxel. To account for the small g1 ( τ ) decay in capillaries where red blood cells are flowing slowly and discontinuously, Intralipid is injected to enhance the OCT signal. We demonstrate that the proposed technique realizes 3-D OCTA with negligible tail projections and the penetrating arteries are readily identified. In addition, compared to regular OCTA, the proposed g1-OCTA largely increased the depth-of-field. This technique provides a more accurate rendering of the vascular 3-D anatomy and has the potential for more quantitative characterization of vascular networks.
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Affiliation(s)
- Jianbo Tang
- Boston University, Neurophotonics Center, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts, United States
- Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
- Address all correspondence to Jianbo Tang, E-mail:
| | - Sefik Evren Erdener
- Boston University, Neurophotonics Center, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts, United States
- Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
| | - Smrithi Sunil
- Boston University, Neurophotonics Center, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - David A. Boas
- Boston University, Neurophotonics Center, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts, United States
- Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
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11
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Gao W. Quantitative depth-resolved microcirculation imaging with optical coherence tomography angiography (Part ΙΙ): Microvascular network imaging. Microcirculation 2018; 25:e12376. [DOI: 10.1111/micc.12376] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 04/11/2017] [Indexed: 11/28/2022]
Affiliation(s)
- Wanrong Gao
- Department of Optical Engineering; Nanjing University of Science and Technology; Nanjing Jiangsu China
- MIIT Key Laboratory of Advanced Solid Laser; Nanjing University of Science and Technology; Nanjing Jiangsu China
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12
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Bernucci MT, Merkle CW, Srinivasan VJ. Investigation of artifacts in retinal and choroidal OCT angiography with a contrast agent. BIOMEDICAL OPTICS EXPRESS 2018; 9:1020-1040. [PMID: 29541501 PMCID: PMC5846511 DOI: 10.1364/boe.9.001020] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 01/22/2018] [Accepted: 01/24/2018] [Indexed: 05/18/2023]
Abstract
Optical coherence tomography angiography (OCTA) has recently emerged for imaging vasculature in clinical ophthalmology. Yet, OCTA images contain artifacts that remain challenging to interpret. To help explain these artifacts, we perform contrast-enhanced OCTA with a custom-designed wide-field ophthalmoscope in rats in vivo. We choose an intravascular contrast agent (Intralipid) with particles that are more isotropically scattering and more symmetrically shaped than red blood cells (RBCs). Then, by examining how OCTA artifacts change after contrast agent injection, we attribute OCTA artifacts to RBC-specific properties. In this work, we investigate retinal and choroidal OCTA in rats with or without melanosomes, both before and after contrast agent injection, at a wavelength at which scattering dominates the image contrast (1300 nm). First, baseline images suggest that high backscattering of choroidal melanosomes accounts for the relatively dark appearance of choroidal vessel lumens in OCTA. Second, Intralipid injection tends to eliminate the hourglass pattern artifact in OCTA images of vessel lumens and highlights vertical capillaries that were previously faint in OCTA, showing that RBC orientation is important in determining OCTA signal. Third, Intralipid injection increases lumen signal without significantly affecting the tails, suggesting that projection artifacts, or tails, are due to RBC multiple scattering. Fourth, Intralipid injection increases the side-to-top signal ratio less in choroidal vessel lumens of pigmented rats, suggesting that melanosome multiple scattering makes the hourglass artifact less prominent. This study provides the first direct experimental in vivo evidence to explain light scattering-related artifacts in OCTA.
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Affiliation(s)
- Marcel T. Bernucci
- Department of Biomedical Engineering, University of California Davis, Davis, California, USA
| | - Conrad W. Merkle
- Department of Biomedical Engineering, University of California Davis, Davis, California, USA
| | - Vivek J. Srinivasan
- Department of Biomedical Engineering, University of California Davis, Davis, California, USA
- Department of Ophthalmology and Vision Science, University of California Davis School of Medicine, Sacramento, California, USA
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13
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Baran U, Choi WJ, Li Y, Wang RK. Tail artifact removal in OCT angiography images of rodent cortex. JOURNAL OF BIOPHOTONICS 2017; 10:1421-1429. [PMID: 27600882 PMCID: PMC5340634 DOI: 10.1002/jbio.201600194] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/16/2016] [Accepted: 08/21/2016] [Indexed: 05/11/2023]
Abstract
Optical coherence tomography angiography (OCTA) is a surging non-invasive, label-free, in vivo volumetric imaging method, currently being translated to clinical ophthalmology and becoming popular in neuroscience. Despite its attractiveness, there is an inherent issue of using OCT angiograms for quantitative cerebrovascular studies: The dynamic scattering of moving erythrocytes within pial vasculature creates tail-like artifacts that shadow the capillary vessels in the deeper layers of cortex. This false flow effect is relatively benign for qualitative visualization purposes, but it might have a significant impact on quantitative interpretation of angiographic results. In this work, we propose a simple image processing method to remove these tail artifacts in depth-resolved OCTA images using an adaptive enface mask generated with OCT structural images. We demonstrate the effectiveness of our method by comparing vessel densities and vessel similarities of depth-resolved OCT angiograms in a stroke study in a rodent model, in vivo. Thanks to the ability of seeing through the tails of pial vessels, capillary vessels beneath these vessels could be recovered to some extend in the deeper layers of mouse cerebral cortex, leading to a more accurate quantification. Tail artifact removed enface OCT angiogram of deeper layer in vivo mouse cortex.
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Affiliation(s)
- Utku Baran
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Department of Electrical Engineering, University of Washington, Seattle, WA, USA
| | - Woo June Choi
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Yuandong Li
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, WA, USA
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14
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Gao W. Quantitative depth-resolved microcirculation imaging with optical coherence tomography angiography (Part Ι): Blood flow velocity imaging. Microcirculation 2017; 25:e12375. [PMID: 28419622 DOI: 10.1111/micc.12375] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 04/11/2017] [Indexed: 12/20/2022]
Abstract
The research goal of the microvascular network imaging with OCT angiography is to achieve depth-resolved blood flow and vessel imaging in vivo in the clinical management of patents. In this review, we review the main phenomena that have been explored in OCT to image the blood flow velocity vector and the vessels of the microcirculation within living tissues. Parameters that limit the accurate measurements of blood flow velocity are then considered. Finally, initial clinical diagnosis applications and future developments of OCT flow images are discussed.
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Affiliation(s)
- Wanrong Gao
- Department of Optical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu, China.,MIIT Key Laboratory of Advanced soIid Laser, Nanjing University of science and Technology, Nanjing, Jiangsu, China
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15
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Augustin M, Fialová S, Himmel T, Glösmann M, Lengheimer T, Harper DJ, Plasenzotti R, Pircher M, Hitzenberger CK, Baumann B. Multi-Functional OCT Enables Longitudinal Study of Retinal Changes in a VLDLR Knockout Mouse Model. PLoS One 2016; 11:e0164419. [PMID: 27711217 PMCID: PMC5053493 DOI: 10.1371/journal.pone.0164419] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 09/23/2016] [Indexed: 12/24/2022] Open
Abstract
We present a multi-functional optical coherence tomography (OCT) imaging approach to study retinal changes in the very-low-density-lipoprotein-receptor (VLDLR) knockout mouse model with a threefold contrast. In the retinas of VLDLR knockout mice spontaneous retinal-chorodoidal neovascularizations form, having an appearance similar to choroidal and retinal neovascularizations (CNV and RNV) in neovascular age-related macular degeneration (AMD) or retinal angiomatous proliferation (RAP). For this longitudinal study, the mice were imaged every 4 to 6 weeks starting with an age of 4 weeks and following up to the age of 11 months. Significant retinal changes were identified by the multi-functional imaging approach offering a threefold contrast: reflectivity, polarization sensitivity (PS) and motion contrast based OCT angiography (OCTA). By use of this intrinsic contrast, the long-term development of neovascularizations was studied and associated processes, such as the migration of melanin pigments or retinal-choroidal anastomosis, were assessed in vivo. Furthermore, the in vivo imaging results were validated with histological sections at the endpoint of the experiment. Multi-functional OCT proves as a powerful tool for longitudinal retinal studies in preclinical research of ophthalmic diseases. Intrinsic contrast offered by the functional extensions of OCT might help to describe regulative processes in genetic animal models and potentially deepen the understanding of the pathogenesis of retinal diseases such as wet AMD.
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Affiliation(s)
- Marco Augustin
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
- * E-mail:
| | - Stanislava Fialová
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Tanja Himmel
- Core Facility for Research and Technology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Martin Glösmann
- Core Facility for Research and Technology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Theresia Lengheimer
- Division of Biomedical Research, Medical University of Vienna, Vienna, Austria
| | - Danielle J. Harper
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Roberto Plasenzotti
- Division of Biomedical Research, Medical University of Vienna, Vienna, Austria
| | - Michael Pircher
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Christoph K. Hitzenberger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Bernhard Baumann
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
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