201
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Nesper PL, Soetikno BT, Zhang HF, Fawzi AA. OCT angiography and visible-light OCT in diabetic retinopathy. Vision Res 2017; 139:191-203. [PMID: 28601429 PMCID: PMC5723235 DOI: 10.1016/j.visres.2017.05.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Revised: 05/23/2017] [Accepted: 05/24/2017] [Indexed: 12/31/2022]
Abstract
In recent years, advances in optical coherence tomography (OCT) techniques have increased our understanding of diabetic retinopathy, an important microvascular complication of diabetes. OCT angiography is a non-invasive method that visualizes the retinal vasculature by detecting motion contrast from flowing blood. Visible-light OCT shows promise as a novel technique for quantifying retinal hypoxia by measuring the retinal oxygen delivery and metabolic rates. In this article, we discuss recent insights provided by these techniques into the vascular pathophysiology of diabetic retinopathy. The next milestones for these modalities are large multicenter studies to establish consensus on the most reliable and consistent outcome parameters to study diabetic retinopathy.
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Affiliation(s)
- Peter L Nesper
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Avenue, Suite 440, Chicago, IL 60611, USA.
| | - Brian T Soetikno
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Avenue, Suite 440, Chicago, IL 60611, USA; Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA; Medical Scientist Training Program, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA.
| | - Hao F Zhang
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Avenue, Suite 440, Chicago, IL 60611, USA; Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA.
| | - Amani A Fawzi
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Avenue, Suite 440, Chicago, IL 60611, USA.
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202
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Abstract
The advent of optical coherence tomography angiography (OCT-A) provides a new opportunity to visualize the retinal vasculature in a non-invasive and dye-free manner which may help identify vascular abnormalities in glaucoma. While a reduction in retinal and optic nerve head vessel densities and blood flow indexes measured by OCT-A has been demonstrated in patients with glaucoma in many studies, it is unclear whether OCT-A provides additional information for the detection and monitoring of glaucoma compared with OCT measurements such as retinal nerve fiber layer thickness, neuroretinal rim width, and ganglion cell inner plexiform layer thickness. Longitudinal studies are needed to elucidate whether vascular abnormalities detected by OCT-A are a cause or a consequence of optic nerve damage in glaucoma.
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Affiliation(s)
- Kelvin H Wan
- Department of Ophthalmology, Tuen Mun Eye Center and Tuen Mun Hospital, Hong Kong, China.,Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Christopher K S Leung
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
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203
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Kashani AH, Chen CL, Gahm JK, Zheng F, Richter GM, Rosenfeld PJ, Shi Y, Wang RK. Optical coherence tomography angiography: A comprehensive review of current methods and clinical applications. Prog Retin Eye Res 2017; 60:66-100. [PMID: 28760677 PMCID: PMC5600872 DOI: 10.1016/j.preteyeres.2017.07.002] [Citation(s) in RCA: 599] [Impact Index Per Article: 85.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 07/20/2017] [Accepted: 07/24/2017] [Indexed: 02/06/2023]
Abstract
OCT has revolutionized the practice of ophthalmology over the past 10-20 years. Advances in OCT technology have allowed for the creation of novel OCT-based methods. OCT-Angiography (OCTA) is one such method that has rapidly gained clinical acceptance since it was approved by the FDA in late 2016. OCTA images are based on the variable backscattering of light from the vascular and neurosensory tissue in the retina. Since the intensity and phase of backscattered light from retinal tissue varies based on the intrinsic movement of the tissue (e.g. red blood cells are moving, but neurosensory tissue is static), OCTA images are essentially motion-contrast images. This motion-contrast imaging provides reliable, high resolution, and non-invasive images of the retinal vasculature in an efficient manner. In many cases, these images are approaching histology level resolution. This unprecedented resolution coupled with the simple, fast and non-invasive imaging platform have allowed a host of basic and clinical research applications. OCTA demonstrates many important clinical findings including areas of macular telangiectasia, impaired perfusion, microaneurysms, capillary remodeling, some types of intraretinal fluid, and neovascularization among many others. More importantly, OCTA provides depth-resolved information that has never before been available. Correspondingly, OCTA has been used to evaluate a spectrum of retinal vascular diseases including diabetic retinopathy (DR), retinal venous occlusion (RVO), uveitis, retinal arterial occlusion, and age-related macular degeneration among others. In this review, we will discuss the methods used to create OCTA images, the practical applications of OCTA in light of invasive dye-imaging studies (e.g. fluorescein angiography) and review clinical studies demonstrating the utility of OCTA for research and clinical practice.
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Affiliation(s)
- Amir H Kashani
- USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of University of Southern California; Los Angeles, CA 90033, United States.
| | - Chieh-Li Chen
- Department of Biomedical Engineering, University of Washington Seattle, Seattle, WA 98195, United States
| | - Jin K Gahm
- Laboratory of Neuro Imaging (LONI), USC Stevens Neuroimaging and Informatics Institute, Keck School of Medicine of University of Southern California, Los Angeles, CA 90033, United States
| | - Fang Zheng
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL 33136, United States
| | - Grace M Richter
- USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of University of Southern California; Los Angeles, CA 90033, United States
| | - Philip J Rosenfeld
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL 33136, United States
| | - Yonggang Shi
- Laboratory of Neuro Imaging (LONI), USC Stevens Neuroimaging and Informatics Institute, Keck School of Medicine of University of Southern California, Los Angeles, CA 90033, United States
| | - Ruikang K Wang
- Department of Biomedical Engineering, University of Washington Seattle, Seattle, WA 98195, United States
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204
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Khan HA, Mehmood A, Khan QA, Iqbal F, Rasheed F, Khan N, Pizzimenti JJ. A major review of optical coherence tomography angiography. EXPERT REVIEW OF OPHTHALMOLOGY 2017. [DOI: 10.1080/17469899.2017.1356229] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Hashim Ali Khan
- Ophthalmology, SEHHAT Foundation Hospital, Main KKH, Danyore, Gilgit, Pakistan
| | - Asim Mehmood
- Ophthalmology, Multan Medical & Dental College, Multan, Pakistan
| | - Qaim Ali Khan
- Ophthalmology, Poonch Medical College, AJK, Pakistan
| | - Fatima Iqbal
- School of Optometry, The University of Faisalabad, Faisalabad, Pakistan
| | - Faisal Rasheed
- Ophthalmology, Sheikh Zayd Medical College, Rahim Yar Khan, Pakistan
| | - Naeemullah Khan
- Ophthalmology, SEHHAT Foundation Hospital, Main KKH, Danyore, Gilgit, Pakistan
| | - Joseph J. Pizzimenti
- Rosenberg School of Optometry, University of the Incarte Word, San Antonio, TX, USA
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205
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Zhu J, Merkle CW, Bernucci MT, Chong SP, Srinivasan VJ. Can OCT Angiography Be Made a Quantitative Blood Measurement Tool? APPLIED SCIENCES-BASEL 2017; 7. [PMID: 30009045 PMCID: PMC6042878 DOI: 10.3390/app7070687] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Optical Coherence Tomography Angiography (OCTA) refers to a powerful class of OCT scanning protocols and algorithms that selectively enhance the imaging of blood vessel lumens, based mainly on the motion and scattering of red blood cells (RBCs). Though OCTA is widely used in clinical and basic science applications for visualization of perfused blood vessels, OCTA is still primarily a qualitative tool. However, more quantitative hemodynamic information would better delineate disease mechanisms, and potentially improve the sensitivity for detecting early stages of disease. Here, we take a broader view of OCTA in the context of microvascular hemodynamics and light scattering. Paying particular attention to the unique challenges presented by capillaries versus larger supplying and draining vessels, we critically assess opportunities and challenges in making OCTA a quantitative tool.
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Affiliation(s)
- Jun Zhu
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, USA
| | - Conrad W. Merkle
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, USA
| | - Marcel T. Bernucci
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, USA
| | - Shau Poh Chong
- 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, School of Medicine, University of California Davis, Sacramento, CA 95817, USA
- Correspondence: ; Tel.: +1-530-752-9277
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206
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Rezaei KA, Zhang Q, Chen CL, Chao J, Wang RK. Retinal and choroidal vascular features in patients with retinitis pigmentosa imaged by OCT based microangiography. Graefes Arch Clin Exp Ophthalmol 2017; 255:1287-1295. [PMID: 28314954 PMCID: PMC11402510 DOI: 10.1007/s00417-017-3633-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 02/06/2017] [Accepted: 03/06/2017] [Indexed: 10/19/2022] Open
Abstract
PURPOSE To image vascular features of retinitis pigmentosa (RP) using optical coherence tomography angiography (OCTA). METHODS Patients with RP were imaged by spectral domain optical coherence tomography based angiography (OCTA). The optical microangiography (OMAG) algorithm was applied to scanned datasets to generate 3D OCTA retinal angiograms, i.e., OMAG angiograms. Motion tracking was used to minimize artifacts due to eye movement, and large field of view OMAG angiograms were achieved through a montage scanning protocol. For better visualization, depth volumes were segmented to separate the superficial retinal layers from deep outer retinal layers. The choriocapillaris and other choroidal layers were also segmented. To investigate the changes in retinal architecture, the inner segment/outer segment (IS/OS) junction to RPE layer was segmented to generate en face structural images through averaging intensity projection. Color fundus images and/or Goldmann visual fields were available for comparison of the findings to OMAG images. RESULTS A total of 25 eyes (13 patients, seven women and six men) diagnosed with RP at various stages were enrolled in this study from October 2014 to January 2016 and imaged by OCTA. The resulting OMAG angiograms provided detailed visualization of retinal and choroidal vascular networks presented within the retina and choroid in a large field of view (FOV) (∼6.7 mm × 6.7 mm). All patients with a severity score greater than 3 showed abnormal microvasculature in both deep retinal and choroidal layers on OMAG images. Images of patients with a score of 4 indicating only peripheral abnormalities demonstrated relatively normal vasculature networks. Microvascular changes in the retinal and choroidal vasculature correlate with structural changes in the slab from IS/OS junction to RPE layer. CONCLUSIONS OCTA is useful in evaluating the microvascular changes in a large FOV encompassing the maculae of patients with RP. The large FOV of OMAG angiograms, enabled by the motion tracking, provides visualization of high definition and high resolution microvascular networks at varying stages of RP. Microvascular imaging may have significant utility in the diagnosis and monitoring of disease progression in RP patients.
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Affiliation(s)
- Kasra A Rezaei
- Department of Ophthalmology, University of Washington, 325 Ninth Avenue, Seattle, WA, 98104, USA.
| | - Qinqin Zhang
- Department of Bioengineering, University of Washington, 3720 15th Ave NE, Seattle, WA, 98195, USA
| | - Chieh-Li Chen
- Department of Bioengineering, University of Washington, 3720 15th Ave NE, Seattle, WA, 98195, USA
| | - Jennifer Chao
- Department of Ophthalmology, University of Washington, 325 Ninth Avenue, Seattle, WA, 98104, USA
| | - Ruikang K Wang
- Department of Bioengineering, University of Washington, 3720 15th Ave NE, Seattle, WA, 98195, USA
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207
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Zhang Q, Chen CL, Chu Z, Zheng F, Miller A, Roisman L, Rafael de Oliveira Dias J, Yehoshua Z, Schaal KB, Feuer W, Gregori G, Kubach S, An L, Stetson PF, Durbin MK, Rosenfeld PJ, Wang RK. Automated Quantitation of Choroidal Neovascularization: A Comparison Study Between Spectral-Domain and Swept-Source OCT Angiograms. Invest Ophthalmol Vis Sci 2017; 58:1506-1513. [PMID: 28273317 PMCID: PMC5361585 DOI: 10.1167/iovs.16-20977] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Purpose To compare the lesion sizes of choroidal neovascularization (CNV) imaged with spectral-domain (SD) and swept-source (SS) optical coherence tomography angiography (OCTA) and measured using an automated detection algorithm. Methods Patients diagnosed with CNV were imaged by SD-OCTA and SS-OCTA systems using 3 × 3-mm and 6 × 6-mm scans. The complex optical microangiography (OMAGC) algorithm was used to generate the OCTA images. Optical coherence tomography A datasets for imaging CNV were derived by segmenting from the outer retina to 8 μm below Bruch's membrane. An artifact removal algorithm was used to generate angiograms free of retinal vessel projection artifacts. An automated detection algorithm was developed to quantify the size of the CNV. Automated measurements were compared with manual measurements. Measurements from SD-OCTA and SS-OCTA instruments were compared as well. Results Twenty-seven eyes from 23 subjects diagnosed with CNV were analyzed. No significant differences were detected between manual and automatic measurements: SD-OCTA 3 × 3-mm (P = 0.61, paired t-test) and 6 × 6-mm (P = 0.09, paired t-test) scans and the SS-OCTA 3 × 3-mm (P = 0.41, paired t-test) and 6 × 6-mm (P = 0.16, paired t-test) scans. Bland-Altman analyses were performed to confirm the agreement between automatic and manual measurements. Mean lesion sizes were significantly larger for the SS-OCTA images compared with the SD-OCTA images: 3 × 3-mm scans (P = 0.011, paired sample t-test) and the 6 × 6-mm scans (P = 0.021, paired t-test). Conclusions The automated algorithm measurements of CNV were in agreement with the hand-drawn measurements. On average, automated SS-OCTA measurements were larger than SD-OCTA measurements and consistent with the results from using hand-drawn measurements.
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Affiliation(s)
- Qinqin Zhang
- Department of Bioengineering, University of Washington, Seattle, Washington, United States
| | - Chieh-Li Chen
- Department of Bioengineering, University of Washington, Seattle, Washington, United States
| | - Zhongdi Chu
- Department of Bioengineering, University of Washington, Seattle, Washington, United States
| | - Fang Zheng
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Andrew Miller
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Luiz Roisman
- Department of Bioengineering, University of Washington, Seattle, Washington, United States 3Department of Ophthalmology, Federal University of São Paulo, Sao Paulo, Brazil
| | - Joao Rafael de Oliveira Dias
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Zohar Yehoshua
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Karen B Schaal
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - William Feuer
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Giovanni Gregori
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Sophie Kubach
- Advanced Development, Carl Zeiss Meditec, Inc., Dublin, California, United States
| | - Lin An
- Advanced Development, Carl Zeiss Meditec, Inc., Dublin, California, United States
| | - Paul F Stetson
- Advanced Development, Carl Zeiss Meditec, Inc., Dublin, California, United States
| | - Mary K Durbin
- Advanced Development, Carl Zeiss Meditec, Inc., Dublin, California, United States
| | - Philip J Rosenfeld
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Ruikang K Wang
- Department of Bioengineering, University of Washington, Seattle, Washington, United States 5Department of Ophthalmology, University of Washington, Seattle, Washington, United States
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208
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Wei DW, Deegan AJ, Wang RK. Automatic motion correction for in vivo human skin optical coherence tomography angiography through combined rigid and nonrigid registration. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:066013. [PMID: 28636065 PMCID: PMC5478967 DOI: 10.1117/1.jbo.22.6.066013] [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] [Indexed: 05/04/2023]
Abstract
When using optical coherence tomography angiography (OCTA), the development of artifacts due to involuntary movements can severely compromise the visualization and subsequent quantitation of tissue microvasculatures. To correct such an occurrence, we propose a motion compensation method to eliminate artifacts from human skin OCTA by means of step-by-step rigid affine registration, rigid subpixel registration, and nonrigid B-spline registration. To accommodate this remedial process, OCTA is conducted using two matching all-depth volume scans. Affine transformation is first performed on the large vessels of the deep reticular dermis, and then the resulting affine parameters are applied to all-depth vasculatures with a further subpixel registration to refine the alignment between superficial smaller vessels. Finally, the coregistration of both volumes is carried out to result in the final artifact-free composite image via an algorithm based upon cubic B-spline free-form deformation. We demonstrate that the proposed method can provide a considerable improvement to the final en face OCTA images with substantial artifact removal. In addition, the correlation coefficients and peak signal-to-noise ratios of the corrected images are evaluated and compared with those of the original images, further validating the effectiveness of the proposed method. We expect that the proposed method can be useful in improving qualitative and quantitative assessment of the OCTA images of scanned tissue beds.
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Affiliation(s)
- David Wei Wei
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - Anthony J. Deegan
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - Ruikang K. Wang
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
- University of Washington, Department of Ophthalmology, Seattle, Washington, United States
- Address all correspondence to: Ruikang K. Wang, E-mail:
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209
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Wang RK, Zhang Q, Li Y, Song S. Optical coherence tomography angiography-based capillary velocimetry. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:66008. [PMID: 28617921 PMCID: PMC5472241 DOI: 10.1117/1.jbo.22.6.066008] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 05/19/2017] [Indexed: 05/05/2023]
Abstract
Challenge persists in the field of optical coherence tomography (OCT) when it is required to quantify capillary blood flow within tissue beds in vivo. We propose a useful approach to statistically estimate the mean capillary flow velocity using a model-based statistical method of eigendecomposition (ED) analysis of the complex OCT signals obtained with the OCT angiography (OCTA) scanning protocol. ED-based analysis is achieved by the covariance matrix of the ensemble complex OCT signals, upon which the eigenvalues and eigenvectors that represent the subsets of the signal makeup are calculated. From this analysis, the signals due to moving particles can be isolated by employing an adaptive regression filter to remove the eigencomponents that represent static tissue signals. The mean frequency (MF) of moving particles can be estimated by the first lag-one autocorrelation of the corresponding eigenvectors. Three important parameters are introduced, including the blood flow signal power representing the presence of blood flow (i.e., OCTA signals), the MF indicating the mean velocity of blood flow, and the frequency bandwidth describing the temporal flow heterogeneity within a scanned tissue volume. The proposed approach is tested using scattering phantoms, in which microfluidic channels are used to simulate the functional capillary vessels that are perfused with the scattering intralipid solution. The results indicate a linear relationship between the MF and mean flow velocity. In vivo animal experiments are also conducted by imaging mouse brain with distal middle cerebral artery ligation to test the capability of the method to image the changes in capillary flows in response to an ischemic insult, demonstrating the practical usefulness of the proposed method for providing important quantifiable information about capillary tissue beds in the investigations of neurological conditions in vivo.
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Affiliation(s)
- Ruikang K. Wang
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
- University of Washington, Department of Ophthalmology, Seattle, Washington, United States
- Address all correspondence to: Ruikang K. Wang, E-mail:
| | - Qinqin Zhang
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - Yuandong Li
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - Shaozhen Song
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
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210
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Sensitivity and specificity of optical coherence tomography angiography (OCT-A) for detection of choroidal neovascularization in real-life practice and varying retinal expertise level. Int Ophthalmol 2017; 38:1051-1060. [PMID: 28547533 DOI: 10.1007/s10792-017-0559-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2016] [Accepted: 05/10/2017] [Indexed: 10/19/2022]
Abstract
PURPOSE To evaluate the diagnostic accuracy of OCT angiography (OCT-A) detecting or predicting choroidal neovascularization (CNV), by ophthalmologists of disparate degrees of skills in retinal diseases, using spectral domain optical coherence tomography (SD-OCT) and fluorescein angiography (FA) as a standard reference. METHODS Retrospective observational case series. Patient presenting maculopathy and complete imaging were included. FA, SD-OCT, OCT-A and FA coupled to SD-OCT images were graded independently for presence or absence of CNV by ophthalmologists with varying expertise levels. RESULTS Overall sensitivity of OCT-A was 85.62% (95% CI 79.04-90.76%) and specificity was 81.51% (95% CI 73.36-88.03). Sensitivity of FA was 74.51% (95% CI 66.84-81.20), and specificity was 82.35% (95% CI 74.30-88.73). Sensitivity of FA + SD-OCT was 92.72% (95% CI 87.34-96.30), and specificity was 90.91% (95% CI 84.31-95.37). CONCLUSION OCT-A has good sensitivity and specificity for the detection of CNV in all expertise level groups. OCT-A may soon become a routine tool for CNV diagnosis and follow-up.
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211
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Men SJ, Chen CL, Wei W, Lai TY, Song SZ, Wang RK. Repeatability of vessel density measurement in human skin by OCT-based microangiography. Skin Res Technol 2017; 23:607-612. [PMID: 28514014 DOI: 10.1111/srt.12379] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/18/2017] [Indexed: 12/26/2022]
Abstract
PURPOSE To investigate the repeatability of vessel density measurement at human arm skin in healthy subjects with OCT-based microangiography (OMAG). METHODS Four locations including volar wrist, volar forearm, shoulder, and volar upper arm were scanned using an optimized swept source OCT system, working at center wavelength of 1300 nm and A-line rate of 100 kHz. Three scans were acquired at each location at the same visit. Vascular images of papillary dermis, reticular dermis, and the whole dermis layer were generated with OMAG processing and automatic segmentation algorithms. The vessel density (VD) of each layer was calculated based on vascular images, and the repeatability of the VD at the same physiological location was thereafter assessed. RESULTS Fifteen healthy volunteers were included. High repeatability of VD was found for wrist, forearm, shoulder, and upper arm (coefficient of variation (CV)=2.4, 2.7, 2.7, 2.0, and intraclass correlation coefficient (ICC)=0.906, 0.854, 0.943, 0.916 respectively). The VD measurements showed no significant difference between the four locations in any of the three layers, ie papillary layer (P=.1063), reticular layer (P=.3371), and whole dermis layer (P=.3233). CONCLUSION Quantification of VD by using OCT/OMAG is repeatable when imaging skin tissue beds in healthy individuals.
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Affiliation(s)
- S J Men
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - C-L Chen
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - W Wei
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - T-Y Lai
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - S Z Song
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - R K Wang
- Department of Bioengineering, University of Washington, Seattle, WA, USA
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212
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Munk MR, Giannakaki-Zimmermann H, Berger L, Huf W, Ebneter A, Wolf S, Zinkernagel MS. OCT-angiography: A qualitative and quantitative comparison of 4 OCT-A devices. PLoS One 2017; 12:e0177059. [PMID: 28489918 PMCID: PMC5425250 DOI: 10.1371/journal.pone.0177059] [Citation(s) in RCA: 159] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 04/23/2017] [Indexed: 01/09/2023] Open
Abstract
Purpose To compare the quality of four OCT-angiography(OCT-A) modules. Method The retina of nineteen healthy volunteers were scanned with four OCT-devices (Topcon DRI-OCT Triton Swept-source OCT, Optovue RTVue-XR, a prototype Spectralis OCT2, Heidelberg-Engineering and Zeiss Cirrus 5000-HD-OCT). The device-software generated en-face OCT-A images of the superficial (SCP) and deep capillary plexuses (DCP) were evaluated and scored by 3 independent retinal imaging experts. The SCP vessel density was assessed using Angiotool-software. After the inter-grader reliability assessment, a consensus grading was performed and the modules were ranked based on their scoring. Results There was no significant difference in the vessel density among the modules (Zeiss 48.7±4%, Optovue 47.9±3%, Topcon 48.3±2%, Heidelberg 46.5±4%, p = 0.2). The numbers of discernible vessel-bifurcations differed significantly on each module (Zeiss 2±0.9 bifurcations, Optovue 2.5±1.2, Topcon 1.3±0.7 and Heidelberg 0.5±0.6, p≤0.001). The ranking of each module differed depending on the evaluated parameter. In the overall ranking, the Zeiss module was superior and in 90% better than the median (Bonferroni corrected p-value = 0.04). Optovue was better than the median in 60%, Topcon in 40% and Heidelberg module in 10%, however these differences were not statistically significant. Conclusion Each of the four evaluated OCT-A modules had particular strengths, which differentiated it from their competitors.
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Affiliation(s)
- Marion R. Munk
- Department of Ophthalmology, Inselspital, Bern University Hospital, University of Bern, Switzerland
- Bern Photographic Reading Center, University of Bern, Switzerland
- * E-mail:
| | - Helena Giannakaki-Zimmermann
- Department of Ophthalmology, Inselspital, Bern University Hospital, University of Bern, Switzerland
- Bern Photographic Reading Center, University of Bern, Switzerland
| | - Lieselotte Berger
- Department of Ophthalmology, Inselspital, Bern University Hospital, University of Bern, Switzerland
- Department of Clinical Research, Inselspital Bern University Hospital, University of Bern, Switzerland
| | - Wolfgang Huf
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Andreas Ebneter
- Department of Ophthalmology, Inselspital, Bern University Hospital, University of Bern, Switzerland
- Department of Clinical Research, Inselspital Bern University Hospital, University of Bern, Switzerland
| | - Sebastian Wolf
- Department of Ophthalmology, Inselspital, Bern University Hospital, University of Bern, Switzerland
- Bern Photographic Reading Center, University of Bern, Switzerland
- Department of Clinical Research, Inselspital Bern University Hospital, University of Bern, Switzerland
| | - Martin S. Zinkernagel
- Department of Ophthalmology, Inselspital, Bern University Hospital, University of Bern, Switzerland
- Bern Photographic Reading Center, University of Bern, Switzerland
- Department of Clinical Research, Inselspital Bern University Hospital, University of Bern, Switzerland
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213
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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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214
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Shin JW, Sung KR, Lee JY, Kwon J, Seong M. Optical coherence tomography angiography vessel density mapping at various retinal layers in healthy and normal tension glaucoma eyes. Graefes Arch Clin Exp Ophthalmol 2017; 255:1193-1202. [DOI: 10.1007/s00417-017-3671-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 03/21/2017] [Accepted: 04/03/2017] [Indexed: 10/19/2022] Open
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215
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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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216
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Cole ED, Moult EM, Dang S, Choi W, Ploner SB, Lee B, Louzada R, Novais E, Schottenhamml J, Husvogt L, Maier A, Fujimoto JG, Waheed NK, Duker JS. The Definition, Rationale, and Effects of Thresholding in OCT Angiography. Ophthalmol Retina 2017; 1:435-447. [PMID: 29034359 DOI: 10.1016/j.oret.2017.01.019] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
PURPOSE To examine the definition, rationale, and effects of thresholding in OCT angiography (OCTA). DESIGN A theoretical description of OCTA thresholding in combination with qualitative and quantitative analysis of the effects of OCTA thresholding in eyes from a retrospective case series. PARTICIPANTS Four eyes were qualitatively examined: 1 from a 27-year-old control, 1 from a 78-year-old exudative age-related macular degeneration (AMD) patient, 1 from a 58-year-old myopic patient, and 1 from a 77-year-old nonexudative AMD patient with geographic atrophy (GA). One eye from a 75-year-old nonexudative AMD patient with GA was quantitatively analyzed. MAIN OUTCOME MEASURES A theoretical thresholding model and a qualitative and quantitative description of the dependency of OCTA on thresholding level. RESULTS Due to the presence of system noise, OCTA thresholding is a necessary step in forming OCTA images; however, thresholding can complicate the relationship between blood flow and OCTA signal. CONCLUSIONS Thresholding in OCTA can cause significant artifacts, which should be considered when interpreting and quantifying OCTA images.
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Affiliation(s)
- Emily D Cole
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts
| | - Eric M Moult
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Sabin Dang
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts
| | - WooJhon Choi
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Stefan B Ploner
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts.,Pattern Recognition Laboratory, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - ByungKun Lee
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Ricardo Louzada
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts.,Federal University of Goiás, Goiânia, Brazil
| | - Eduardo Novais
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts.,Federal University of São Paulo, School of Medicine, São Paulo, Brazil
| | - Julia Schottenhamml
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts.,Pattern Recognition Laboratory, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Lennart Husvogt
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts.,Pattern Recognition Laboratory, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Andreas Maier
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts.,Pattern Recognition Laboratory, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - James G Fujimoto
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Nadia K Waheed
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts
| | - Jay S Duker
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts
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217
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Heisler M, Lee S, Mammo Z, Jian Y, Ju M, Merkur A, Navajas E, Balaratnasingam C, Beg MF, Sarunic MV. Strip-based registration of serially acquired optical coherence tomography angiography. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:36007. [PMID: 28265647 DOI: 10.1117/1.jbo.22.3.036007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 02/20/2017] [Indexed: 05/18/2023]
Abstract
The visibility of retinal microvasculature in optical coherence tomography angiography (OCT-A) images is negatively affected by the small dimension of the capillaries, pulsatile blood flow, and motion artifacts. Serial acquisition and time-averaging of multiple OCT-A images can enhance the definition of the capillaries and result in repeatable and consistent visualization. We demonstrate an automated method for registration and averaging of serially acquired OCT-A images. Ten OCT-A volumes from six normal control subjects were acquired using our prototype 1060-nm swept source OCT system. The volumes were divided into microsaccade-free en face angiogram strips, which were affine registered using scale-invariant feature transform keypoints, followed by nonrigid registration by pixel-wise local neighborhood matching. The resulting averaged images were presented of all the retinal layers combined, as well as in the superficial and deep plexus layers separately. The contrast-to-noise ratio and signal-to-noise ratio of the angiograms with all retinal layers (reported as average ± standard deviation ) increased from 0.52 ± 0.22 and 19.58 ± 4.04 ?? dB for a single image to 0.77 ± 0.25 and 25.05 ± 4.73 ?? dB , respectively, for the serially acquired images after registration and averaging. The improved visualization of the capillaries can enable robust quantification and study of minute changes in retinal microvasculature.
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Affiliation(s)
- Morgan Heisler
- Simon Fraser University, School of Engineering Science, Faculty of Applied Sciences, Burnaby, British Columbia, Canada
| | - Sieun Lee
- Simon Fraser University, School of Engineering Science, Faculty of Applied Sciences, Burnaby, British Columbia, Canada
| | - Zaid Mammo
- University of British Columbia, Department of Ophthalmology and Visual Sciences, Vancouver, British Columbia, Canada
| | - Yifan Jian
- Simon Fraser University, School of Engineering Science, Faculty of Applied Sciences, Burnaby, British Columbia, Canada
| | - MyeongJin Ju
- Simon Fraser University, School of Engineering Science, Faculty of Applied Sciences, Burnaby, British Columbia, Canada
| | - Andrew Merkur
- University of British Columbia, Department of Ophthalmology and Visual Sciences, Vancouver, British Columbia, Canada
| | - Eduardo Navajas
- University of British Columbia, Department of Ophthalmology and Visual Sciences, Vancouver, British Columbia, Canada
| | - Chandrakumar Balaratnasingam
- University of British Columbia, Department of Ophthalmology and Visual Sciences, Vancouver, British Columbia, CanadacUniversity of Western Australia, Lions Eye Institute, Centre for Ophthalmology and Visual Science, Department of Physiology and Pharmacology, Nedlands, AustraliadVitreous Retina Macula Consultants of New York, New York, United StateseManhattan Eye, Ear and Throat Hospital, LuEsther T. Mertz Retinal Research Center, New York, New York, United States
| | - Mirza Faisal Beg
- Simon Fraser University, School of Engineering Science, Faculty of Applied Sciences, Burnaby, British Columbia, Canada
| | - Marinko V Sarunic
- Simon Fraser University, School of Engineering Science, Faculty of Applied Sciences, Burnaby, British Columbia, Canada
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218
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Zhang Q, Zhang A, Lee CS, Lee AY, Rezaei KA, Roisman L, Miller A, Zheng F, Gregori G, Durbin MK, An L, Stetson PF, Rosenfeld PJ, Wang RK. Projection artifact removal improves visualization and quantitation of macular neovascularization imaged by optical coherence tomography angiography. Ophthalmol Retina 2017; 1:124-136. [PMID: 28584883 DOI: 10.1016/j.oret.2016.08.005] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
PURPOSE To visualize and quantify the size and vessel density of macular neovascularization (MNV) using optical coherence tomography angiography (OCTA) with a projection artifact removal algorithm. DESIGN Multicenter, observational study. PARTICIPANTS Subjects with MNV in at least one eye. METHODS Patients were imaged using either a swept-source OCT angiography (SS-OCTA) prototype system or a spectral-domain OCT angiography (SD-OCTA) prototype system. The optical microangiography (OMAG) algorithm was used to generate the OCTA images. Projection artifacts from the overlying retinal circulation were removed from the OMAG OCTA images using a novel algorithm. Following removal of the projection artifacts from the OCTA images, we assessed the size and vascularity of the MNV. Concurrent fluorescein angiography (FA) and indocyanine green angiography (ICGA) images were used to validate the artifact-free OMAG images whenever available. MAIN OUTCOME MEASURES Size and vascularity of MNV imaged with OCTA before and after the use of a projection-artifact removal algorithm. RESULTS A total of 30 subjects (40 eyes) diagnosed with MNV were imaged. Five patients were imaged before and after intravitreal injections of vascular endothelial growth factor (VEGF) inhibitors. Following the use of the projection artifact removal algorithm, we found improved visualization of the MNV. Lesion sizes and vascular densities were more easily measured on all the artifact-free OMAG images. In eyes treated with vascular endothelial growth factor inhibitors, vascular density was reduced in all five eyes after treatment, and in four eyes, the size of the MNV decreased. One of five patients showed a slight increase in lesion size, but a decrease in vascular density. CONCLUSIONS OCTA imaging of MNV using the OMAG algorithm combined with removal of projection artifacts resulted in improved visualization and measurements of the neovascular lesions. OMAG with projection artifact removal should be useful for assessing the response of MNV to treatment using OCTA imaging.
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Affiliation(s)
- Qinqin Zhang
- University of Washington, Department of Bioengineering, Seattle, Washington
| | - Anqi Zhang
- University of Washington, Department of Bioengineering, Seattle, Washington
| | - Cecilia S Lee
- University of Washington, Department of Ophthalmology, Seattle, Washington
| | - Aaron Y Lee
- University of Washington, Department of Ophthalmology, Seattle, Washington
| | - Kasra A Rezaei
- University of Washington, Department of Ophthalmology, Seattle, Washington
| | - Luiz Roisman
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - Andrew Miller
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - Fang Zheng
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - Giovani Gregori
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - Mary K Durbin
- Advanced Development, Carl Zeiss Meditec, Inc., Dublin, CA
| | - Lin An
- Advanced Development, Carl Zeiss Meditec, Inc., Dublin, CA
| | - Paul F Stetson
- Advanced Development, Carl Zeiss Meditec, Inc., Dublin, CA
| | - Philip J Rosenfeld
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - Ruikang K Wang
- University of Washington, Department of Bioengineering, Seattle, Washington
- University of Washington, Department of Ophthalmology, Seattle, Washington
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219
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Chen CL, Wang RK. Optical coherence tomography based angiography [Invited]. BIOMEDICAL OPTICS EXPRESS 2017; 8:1056-1082. [PMID: 28271003 PMCID: PMC5330554 DOI: 10.1364/boe.8.001056] [Citation(s) in RCA: 270] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 01/16/2017] [Indexed: 05/18/2023]
Abstract
Optical coherence tomography (OCT)-based angiography (OCTA) provides in vivo, three-dimensional vascular information by the use of flowing red blood cells as intrinsic contrast agents, enabling the visualization of functional vessel networks within microcirculatory tissue beds non-invasively, without a need of dye injection. Because of these attributes, OCTA has been rapidly translated to clinical ophthalmology within a short period of time in the development. Various OCTA algorithms have been developed to detect the functional micro-vasculatures in vivo by utilizing different components of OCT signals, including phase-signal-based OCTA, intensity-signal-based OCTA and complex-signal-based OCTA. All these algorithms have shown, in one way or another, their clinical values in revealing micro-vasculatures in biological tissues in vivo, identifying abnormal vascular networks or vessel impairment zones in retinal and skin pathologies, detecting vessel patterns and angiogenesis in eyes with age-related macular degeneration and in skin and brain with tumors, and monitoring responses to hypoxia in the brain tissue. The purpose of this paper is to provide a technical oriented overview of the OCTA developments and their potential pre-clinical and clinical applications, and to shed some lights on its future perspectives. Because of its clinical translation to ophthalmology, this review intentionally places a slightly more weight on ophthalmic OCT angiography.
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Affiliation(s)
- Chieh-Li Chen
- Department of Bioengineering, University of Washington, 3720 15th Ave NE, Seattle, WA 98195, USA
- Department of Ophthalmology, University of Washington, 325 9th Ave, Seattle, WA 98104, USA
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, 3720 15th Ave NE, Seattle, WA 98195, USA
- Department of Ophthalmology, University of Washington, 325 9th Ave, Seattle, WA 98104, USA
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220
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Aden A, Anderson P, Burnett GR, Lynch RJM, Tomlins PH. Longitudinal correlation of 3D OCT to detect early stage erosion in bovine enamel. BIOMEDICAL OPTICS EXPRESS 2017; 8:954-973. [PMID: 28270996 PMCID: PMC5330568 DOI: 10.1364/boe.8.000954] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 10/28/2016] [Accepted: 11/19/2016] [Indexed: 06/06/2023]
Abstract
Erosive tissue-loss in dental enamel is of significant clinical concern because the net loss of enamel is irreversible, however, initial erosion is reversible. Micro-hardness testing is a standard method for measuring initial erosion, but its invasive nature has led to the investigation of alternative measurement techniques. Optical coherence tomography (OCT) is an attractive alternative because of its ability to non-invasively image three-dimensional volumes. In this study, a four-dimensional OCT system is used to longitudinally measure bovine enamel undergoing a continuous erosive challenge. A new method of analyzing 3D OCT volumes is introduced that compares intensity projections of the specimen surface by calculating the slope of a linear regression line between corresponding pixel intensities and the associated correlation coefficient. The OCT correlation measurements are compared to micro-hardness data and found to exhibit a linear relationship. The results show that this method is a sensitive technique for the investigation of the formation of early stage erosive lesions.
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Affiliation(s)
- Abdirahman Aden
- Barts & The London School of Medicine and Dentistry, Institute of Dentistry, Queen Mary University of London, E1 1BB, UK
| | - Paul Anderson
- Barts & The London School of Medicine and Dentistry, Institute of Dentistry, Queen Mary University of London, E1 1BB, UK
| | - Gary R Burnett
- GSK Consumer Healthcare, St. Georges Avenue, Weybridge, Surrey, KT13 0DE, UK
| | - Richard J M Lynch
- GSK Consumer Healthcare, St. Georges Avenue, Weybridge, Surrey, KT13 0DE, UK
| | - Peter H Tomlins
- Barts & The London School of Medicine and Dentistry, Institute of Dentistry, Queen Mary University of London, E1 1BB, UK
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221
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Mo S, Phillips E, Krawitz BD, Garg R, Salim S, Geyman LS, Efstathiadis E, Carroll J, Rosen RB, Chui TYP. Visualization of Radial Peripapillary Capillaries Using Optical Coherence Tomography Angiography: The Effect of Image Averaging. PLoS One 2017; 12:e0169385. [PMID: 28068370 PMCID: PMC5222511 DOI: 10.1371/journal.pone.0169385] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 12/15/2016] [Indexed: 01/03/2023] Open
Abstract
Objectives To assess the effect of image registration and averaging on the visualization and quantification of the radial peripapillary capillary (RPC) network on optical coherence tomography angiography (OCTA). Methods Twenty-two healthy controls were imaged with a commercial OCTA system (AngioVue, Optovue, Inc.). Ten 10x10° scans of the optic disc were obtained, and the most superficial layer (50-μm slab extending from the inner limiting membrane) was extracted for analysis. Rigid registration was achieved using ImageJ, and averaging of each 2 to 10 frames was performed in five ~2x2° regions of interest (ROI) located 1° from the optic disc margin. The ROI were automatically skeletonized. Signal-to-noise ratio (SNR), number of endpoints and mean capillary length from the skeleton, capillary density, and mean intercapillary distance (ICD) were measured for the reference and each averaged ROI. Repeated measures analysis of variance was used to assess statistical significance. Three patients with primary open angle glaucoma were also imaged to compare RPC density to controls. Results Qualitatively, vessels appeared smoother and closer to histologic descriptions with increasing number of averaged frames. Quantitatively, number of endpoints decreased by 51%, and SNR, mean capillary length, capillary density, and ICD increased by 44%, 91%, 11%, and 4.5% from single frame to 10-frame averaged, respectively. The 10-frame averaged images from the glaucomatous eyes revealed decreased density correlating to visual field defects and retinal nerve fiber layer thinning. Conclusions OCTA image registration and averaging is a viable and accessible method to enhance the visualization of RPCs, with significant improvements in image quality and RPC quantitative parameters. With this technique, we will be able to non-invasively and reliably study RPC involvement in diseases such as glaucoma.
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Affiliation(s)
- Shelley Mo
- Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York, United States of America
| | - Erika Phillips
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Brian D Krawitz
- Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York, United States of America
| | - Reena Garg
- Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York, United States of America
| | - Sarwat Salim
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Lawrence S Geyman
- Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York, United States of America
| | - Eleni Efstathiadis
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York, United States of America
- William E. Macaulay Honors College, New York, New York, United States of America
| | - Joseph Carroll
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Richard B Rosen
- Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York, United States of America
| | - Toco Y P Chui
- Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York, United States of America
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222
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Xu J, Song S, Wei W, Wang RK. Wide field and highly sensitive angiography based on optical coherence tomography with akinetic swept source. BIOMEDICAL OPTICS EXPRESS 2017; 8:420-435. [PMID: 28101428 PMCID: PMC5231310 DOI: 10.1364/boe.8.000420] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 12/15/2016] [Accepted: 12/18/2016] [Indexed: 05/03/2023]
Abstract
Wide-field vascular visualization in bulk tissue that is of uneven surface is challenging due to the relatively short ranging distance and significant sensitivity fall-off for most current optical coherence tomography angiography (OCTA) systems. We report a long ranging and ultra-wide-field OCTA (UW-OCTA) system based on an akinetic swept laser. The narrow instantaneous linewidth of the swept source with its high phase stability, combined with high-speed detection in the system enable us to achieve long ranging (up to 46 mm) and almost negligible system sensitivity fall-off. To illustrate these advantages, we compare the basic system performances between conventional spectral domain OCTA and UW-OCTA systems and their functional imaging of microvascular networks in living tissues. In addition, we show that the UW-OCTA is capable of different depth-ranging of cerebral blood flow within entire brain in mice, and providing unprecedented blood perfusion map of human finger in vivo. We believe that the UW-OCTA system has promises to augment the existing clinical practice and explore new biomedical applications for OCT imaging.
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223
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Daneshvar R, Nouri-Mahdavi K. Optical Coherence Tomography Angiography: A New Tool in Glaucoma Diagnostics and Research. J Ophthalmic Vis Res 2017; 12:325-332. [PMID: 28791067 PMCID: PMC5525503 DOI: 10.4103/jovr.jovr_36_17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Optical coherence tomography angiography (OCTA) is a new modality in ocular imaging which provides high resolution view of the vascular structures in the retina and optic nerve head. This technology has the advantages of being noninvasive, rapid and reproducible. OCTA is becoming a valuable tool for evaluating many retinal and optic nerve diseases. This article provides a brief introduction to the technology and its application in the field of glaucoma diagnostics.
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Affiliation(s)
- Ramin Daneshvar
- Glaucoma Division, Stein Eye Institute, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA.,Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Kouros Nouri-Mahdavi
- Glaucoma Division, Stein Eye Institute, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA
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224
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Salas M, Augustin M, Ginner L, Kumar A, Baumann B, Leitgeb R, Drexler W, Prager S, Hafner J, Schmidt-Erfurth U, Pircher M. Visualization of micro-capillaries using optical coherence tomography angiography with and without adaptive optics. BIOMEDICAL OPTICS EXPRESS 2017; 8:207-222. [PMID: 28101412 PMCID: PMC5231293 DOI: 10.1364/boe.8.000207] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 11/10/2016] [Accepted: 12/06/2016] [Indexed: 05/18/2023]
Abstract
The purpose of this work is to investigate the benefits of adaptive optics (AO) technology for optical coherence tomography angiography (OCTA). OCTA has shown great potential in non-invasively enhancing the contrast of vessels and small capillaries. Especially the capability of the technique to visualize capillaries with a lateral extension that is below the transverse resolution of the system opens unique opportunities in diagnosing retinal vascular diseases. However, there are some limitations of this technology such as shadowing and projection artifacts caused by overlying vasculature or the inability to determine the true extension of a vessel. Thus, the evaluation of the vascular structure and density based on OCTA alone can be misleading. In this paper we compare the performance of AO-OCT, AO-OCTA and OCTA for imaging retinal vasculature. The improved transverse resolution and the reduced depth of focus of AO-OCT and AO-OCTA greatly reduce shadowing artifacts allowing for a better differentiation and segmentation of different vasculature layers of the inner retina. The comparison is done on images recorded in healthy volunteers and in diabetic patients with distinct pathologies of the retinal microvasculature.
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Affiliation(s)
- Matthias Salas
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Marco Augustin
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Laurin Ginner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
- Christian Doppler Laboratory for Innovative Optical Imaging and Its Translation to Medicine, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Abhishek Kumar
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Bernhard Baumann
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Rainer Leitgeb
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
- Christian Doppler Laboratory for Innovative Optical Imaging and Its Translation to Medicine, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Wolfgang Drexler
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Sonja Prager
- Department of Ophthalmology and Optometry, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Julia Hafner
- Department of Ophthalmology and Optometry, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Ursula Schmidt-Erfurth
- Department of Ophthalmology and Optometry, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Michael Pircher
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
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225
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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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226
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Chen Y, Trinh LA, Fingler J, Fraser SE. Phase variance optical coherence microscopy for label-free imaging of the developing vasculature in zebrafish embryos. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:126022. [PMID: 28036094 DOI: 10.1117/1.jbo.21.12.126022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 12/05/2016] [Indexed: 06/06/2023]
Abstract
A phase variance optical coherence microscope (pvOCM) has been created to image blood flow in the microvasculature of zebrafish embryos, without the use of exogenous labels. The pvOCM imaging system has axial and lateral resolutions of 2.8 ?? ? m in tissue and imaging depth of more than 100 ?? ? m . Images of 2 to 5 days postfertilization zebrafish embryos identified the detailed anatomical structure based on OCM intensity contrast. Phase variance contrast offered visualization of blood flow in the arteries, veins, and capillaries. The pvOCM images of the vasculature were confirmed by direct comparisons with fluorescence microscopy images of transgenic embryos in which the vascular endothelium is labeled with green fluorescent protein. The ability of pvOCM to capture activities of regional blood flow permits it to reveal functional information that is of great utility for the study of vascular development.
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Affiliation(s)
- Yu Chen
- University of Southern California, Translational Imaging Center, Los Angeles, California 90089, United StatesbUniversity of Southern California, Department of Biomedical Engineering, Los Angeles, California 90089, United States
| | - Le A Trinh
- University of Southern California, Translational Imaging Center, Los Angeles, California 90089, United States
| | - Jeff Fingler
- Varocto Inc., 1586 North Batavia Street, Orange, California 92867, United States
| | - Scott E Fraser
- University of Southern California, Translational Imaging Center, Los Angeles, California 90089, United StatesbUniversity of Southern California, Department of Biomedical Engineering, Los Angeles, California 90089, United States
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227
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Sencan I, Huang BK, Bian Y, Mis E, Khokha MK, Cao H, Choma M. Ultrahigh-speed, phase-sensitive full-field interferometric confocal microscopy for quantitative microscale physiology. BIOMEDICAL OPTICS EXPRESS 2016; 7:4674-4684. [PMID: 27896006 PMCID: PMC5119606 DOI: 10.1364/boe.7.004674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 10/17/2016] [Accepted: 10/17/2016] [Indexed: 05/05/2023]
Abstract
We developed ultra-high-speed, phase-sensitive, full-field reflection interferometric confocal microscopy (FFICM) for the quantitative characterization of in vivo microscale biological motions and flows. We demonstrated 2D frame rates in excess of 1 kHz and pixel throughput rates up to 125 MHz. These fast FFICM frame rates were enabled by the use of a low spatial coherence, high-power laser source. Specifically, we used a dense vertical cavity surface emitting laser (VCSEL) array that synthesized low spatial coherence light through a large number of narrowband, mutually-incoherent emitters. Off-axis interferometry enabled single-shot acquisition of the complex-valued interferometric signal. We characterized the system performance (~2 μm lateral resolution, ~8 μm axial gating depth) with a well-known target. We also demonstrated the use of this highly parallelized confocal microscopy platform for visualization and quantification of cilia-driven surface flows and cilia beat frequency in an important animal model (Xenopus embryos) with >1 kHz frame rate. Such frame rates are needed to see large changes in local flow velocity over small distance (high shear flow), in this case, local flow around a single ciliated cell. More generally, our results are an important demonstration of low-spatial coherence, high-power lasers in high-performance, quantitative biomedical imaging.
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Affiliation(s)
- Ikbal Sencan
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT 06511, USA; Current affiliation: MGH/HST Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA;
| | - Brendan K Huang
- Biomedical Engineering, Yale University, New Haven, CT 06511, USA
| | - Yong Bian
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT 06511, USA; Current affiliation: Department of Otology and Laryngology, Harvard Medical School, Massachusetts Eye and Ear Infirmary 243 Charles Street, Boston, MA 02114, USA
| | - Emily Mis
- Pediatrics, Yale University, New Haven, CT 06511, USA
| | | | - Hui Cao
- Applied Physics, Yale University, New Haven, CT 06511, USA
| | - Michael Choma
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT 06511, USA; Biomedical Engineering, Yale University, New Haven, CT 06511, USA; Pediatrics, Yale University, New Haven, CT 06511, USA; Applied Physics, Yale University, New Haven, CT 06511, USA;
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228
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Li Y, Choi WJ, Qin W, Baran U, Habenicht LM, Wang RK. Optical coherence tomography based microangiography provides an ability to longitudinally image arteriogenesis in vivo. J Neurosci Methods 2016; 274:164-171. [PMID: 27751893 DOI: 10.1016/j.jneumeth.2016.10.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 10/11/2016] [Accepted: 10/13/2016] [Indexed: 11/19/2022]
Abstract
BACKGROUND Arteriogenesis describes the active growth of the pre-existing collateral arterioles, which is a crucial tissue-saving process in occlusive vascular diseases. NEW METHOD We propose to use optical coherence tomography (OCT)-based microangiography (OMAG) to monitor arteriogenesis following artery transection in mouse ear and focal stroke in mouse brain. RESULTS Our longitudinal mouse ear study shows that the growth phase of arteriogenesis, indicated by changes in collateral vessel diameter and velocity, occurs between 12 and 24h after vessel transection. Additionally, the magnitude of local inflammation is consistent with the time course of arteriogenesis, judging by the tissue thickness measurement and lymphatic vessel signals in OCT. In the mouse brain study, collateral vessel morphology, blood flow velocity and directionality are identified, and an activation of the collateral flow at the arteriolo-arteriolar anastomoses (AAA) is observed during stroke. COMPARISON WITH EXISTING METHODS In comparison with histology and fluorescence imaging, OCT/OMAG is completely non-invasive and capable of producing consistent results of longitudinal changes in collateral vessel morphology and vasodynamics. CONCLUSION OCT/OMAG is a promising imaging tool for longitudinal study of collateral vessel remodeling in small animals. This technique can be applied in guiding the in vivo experiments of arteriogenesis stimulation to treat occlusive vascular diseases, including stroke.
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Affiliation(s)
- Yuandong Li
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Woo June Choi
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Wan Qin
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Utku Baran
- Department of Bioengineering, University of Washington, Seattle, WA, USA; Department of Electrical Engineering, University of Washington, Seattle, WA, USA
| | - Lauren M Habenicht
- Department of Comparative Medicine, University of Washington, Seattle, WA, USA
| | - Ruikang K Wang
- Department of Bioengineering, University of Washington, Seattle, WA, USA.
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229
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Qin W, Roberts MA, Qi X, Murry CE, Zheng Y, Wang RK. Depth-resolved 3D visualization of coronary microvasculature with optical microangiography. Phys Med Biol 2016; 61:7536-7550. [PMID: 27716639 DOI: 10.1088/0031-9155/61/21/7536] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In this study, we propose a novel implementation of optical coherence tomography-based angiography combined with ex vivo perfusion of fixed hearts to visualize coronary microvascular structure and function. The extracorporeal perfusion of Intralipid solution allows depth-resolved angiographic imaging, control of perfusion pressure, and high-resolution optical microangiography. The imaging technique offers new opportunities for microcirculation research in the heart, which has been challenging due to motion artifacts and the lack of independent control of pressure and flow. With the ability to precisely quantify structural and functional features, this imaging platform has broad potential for the study of the pathophysiology of microvasculature in the heart as well as other organs.
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Affiliation(s)
- Wan Qin
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
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230
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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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231
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Mammo Z, Heisler M, Balaratnasingam C, Lee S, Yu DY, Mackenzie P, Schendel S, Merkur A, Kirker A, Albiani D, Navajas E, Beg MF, Morgan W, Sarunic MV. Quantitative Optical Coherence Tomography Angiography of Radial Peripapillary Capillaries in Glaucoma, Glaucoma Suspect, and Normal Eyes. Am J Ophthalmol 2016; 170:41-49. [PMID: 27470061 DOI: 10.1016/j.ajo.2016.07.015] [Citation(s) in RCA: 142] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Revised: 07/18/2016] [Accepted: 07/18/2016] [Indexed: 11/27/2022]
Abstract
PURPOSE To evaluate the quantitative characteristics of the radial peripapillary capillary (RPC) network in glaucoma, glaucoma suspect, and normal eyes using speckle variance optical coherence tomography angiography (OCT-A). To determine correlations between RPC density, nerve fiber layer (NFL) thickness, and visual field indices. DESIGN Cross-sectional study. METHODS OCT-A images of RPCs were acquired at a single institution using a custom-built 1060 nm system from 3 groups: unilateral glaucoma (10 eyes from 5 subjects), glaucoma suspects (6 eyes from 3 subjects), and normal control eyes (16 eyes from 9 normal subjects). Peripapillary NFL thickness measurements were determined using spectral-domain optical coherence tomography. Glaucoma and glaucoma suspects also underwent automated 30-2 Humphrey visual field analysis. Manual tracing techniques were used to quantify RPC density in the OCT-A images. Data were analyzed using a linear mixed model with 1 fixed-effect covariate. Correlations between main outcome measures (RPC density, NFL thickness, and visual field index) were determined. RESULTS Mean age was not significantly different between the 3 groups (P = .25). The density of RPCs was significantly lower in glaucomatous eyes compared with matched-peripapillary regions in the fellow eye, glaucoma suspect group, and normal group (all P < .001). RPC density was strongly correlated with NFL thickness (P < .001) and visual field index (P < .001). CONCLUSIONS Significant reductions in RPC density were correlated with sites of NFL decrease and visual field loss in glaucoma. Speckle variance OCT-A allows visualization and quantification of RPCs and may therefore be a useful tool for indirectly quantifying and monitoring retinal ganglion cell axonal injury in glaucoma.
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Affiliation(s)
- Zaid Mammo
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Morgan Heisler
- School of Engineering Science, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Chandrakumar Balaratnasingam
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada; Vitreous Retina Macula Consultants of New York, New York, New York; LuEsther T. Mertz Retinal Research Center, Eye, Ear and Throat Hospital, New York, New York; Department of Physiology and Pharmacology, Centre for Ophthalmology and Visual Science, Lions Eye Institute, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Sieun Lee
- School of Engineering Science, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Dao-Yi Yu
- Department of Physiology and Pharmacology, Centre for Ophthalmology and Visual Science, Lions Eye Institute, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Paul Mackenzie
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada; School of Engineering Science, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Steven Schendel
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Andrew Merkur
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Andrew Kirker
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - David Albiani
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Eduardo Navajas
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mirza Faisal Beg
- School of Engineering Science, Simon Fraser University, Burnaby, British Columbia, Canada
| | - William Morgan
- Department of Physiology and Pharmacology, Centre for Ophthalmology and Visual Science, Lions Eye Institute, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Marinko V Sarunic
- School of Engineering Science, Simon Fraser University, Burnaby, British Columbia, Canada.
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232
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Zhang Q, Wang J, Wang RK. Highly efficient eigen decomposition based statistical optical microangiography. Quant Imaging Med Surg 2016; 6:557-563. [PMID: 27942476 DOI: 10.21037/qims.2016.10.03] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND To overcome the drawbacks of the voxel-based eigen-decomposition (vED) approach to achieve the purpose of imaging blood flow in living tissue in real time. METHODS A highly efficient and practical method for contrasting in vivo blood flow by applying eigen-decomposition (ED) filter on repeated complex-valued optical coherence tomography (OCT) B-scans eigen-decomposition (bED) is proposed. We first present basic mathematics for bED. We then validate the bED through imaging cerebral blood flow in a mouse model. RESULTS Through evaluating signal to noise ratio, contrast and vessel connectivity, it is found that the proposed method can better contrast blood flow with drastic saving on computational power when compared with traditional ED approach where the filtering is applied on the basis of pixel by pixel or voxel by voxel. CONCLUSIONS The bED is practically feasible to realize real time OCT angiography. In addition, the proposed ED approach is equally applicable to the operations on repeated A-scans or volumetric scans.
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Affiliation(s)
- Qinqin Zhang
- Department of Bioengineering, University of Washington, Seattle, Washington 98195, USA
| | - Jingang Wang
- Department of Bioengineering, University of Washington, Seattle, Washington 98195, USA
| | - Ruikang K Wang
- Department of Bioengineering, University of Washington, Seattle, Washington 98195, USA; Department of Ophthalmology, University of Washington, Seattle, Washington 98195, USA
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233
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Li P, Cheng Y, Li P, Zhou L, Ding Z, Ni Y, Pan C. Hybrid averaging offers high-flow contrast by cost apportionment among imaging time, axial, and lateral resolution in optical coherence tomography angiography. OPTICS LETTERS 2016; 41:3944-7. [PMID: 27607943 DOI: 10.1364/ol.41.003944] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The current temporal, wavelength, angular, and spatial averaging approaches trade imaging time and resolution for multiple independent measurements that improve the flow contrast in optical coherence tomography angiography (OCTA). We find that these averaging approaches are equivalent in principle, offering almost the same flow contrast enhancement as the number of averages increases. Based on this finding, we propose a hybrid averaging strategy for contrast enhancement by cost apportionment. We demonstrate that, compared with any individual approach, the hybrid averaging is able to offer a desired flow contrast without severe degradation of imaging time and resolution. Making use of the extended range of a VCSEL-based swept-source OCT, an angular averaging approach by path length encoding is also demonstrated for flow contrast enhancement.
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234
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Themstrup L, Welzel J, Ciardo S, Kaestle R, Ulrich M, Holmes J, Whitehead R, Sattler E, Kindermann N, Pellacani G, Jemec G. Validation of Dynamic optical coherence tomography for non-invasive, in vivo microcirculation imaging of the skin. Microvasc Res 2016; 107:97-105. [DOI: 10.1016/j.mvr.2016.05.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 05/13/2016] [Accepted: 05/23/2016] [Indexed: 11/15/2022]
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235
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Su JP, Chandwani R, Gao SS, Pechauer AD, Zhang M, Wang J, Jia Y, Huang D, Liu G. Calibration of optical coherence tomography angiography with a microfluidic chip. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:86015. [PMID: 27557344 PMCID: PMC4995373 DOI: 10.1117/1.jbo.21.8.086015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 08/09/2016] [Indexed: 05/17/2023]
Abstract
A microfluidic chip with microchannels ranging from 8 to 96 μm was used to mimic blood vessels down to the capillary level. Blood flow within the microfluidic channels was analyzed with split-spectrum amplitude-decorrelation angiography (SSADA)-based optical coherence tomography (OCT) angiography. It was found that the SSADA decorrelation value was related to both blood flow speed and channel width. SSADA could differentiate nonflowing blood inside the microfluidic channels from static paper. The SSADA decorrelation value was approximately linear with blood flow velocity up to a threshold Vsat of 5.83±1.33 mm/s (mean±standard deviation over the range of channel widths). Beyond this threshold, it approached a saturation value Dsat. Dsat was higher for wider channels, and approached a maximum value Dsm as the channel width became much larger than the beam focal spot diameter. These results indicate that decorrelation values (flow signal) in capillary networks would be proportional to both flow velocity and vessel caliber but would be capped at a saturation value in larger blood vessels. These findings are useful for interpretation and quantification of clinical OCT angiography results.
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Affiliation(s)
- Johnny P. Su
- Oregon Health and Science University, Casey Eye Institute, 3375 Southwest Terwilliger Boulevard, Portland, Oregon 97239, United States
| | - Rahul Chandwani
- Oregon Health and Science University, Casey Eye Institute, 3375 Southwest Terwilliger Boulevard, Portland, Oregon 97239, United States
| | - Simon S. Gao
- Oregon Health and Science University, Casey Eye Institute, 3375 Southwest Terwilliger Boulevard, Portland, Oregon 97239, United States
| | - Alex D. Pechauer
- Oregon Health and Science University, Casey Eye Institute, 3375 Southwest Terwilliger Boulevard, Portland, Oregon 97239, United States
| | - Miao Zhang
- Oregon Health and Science University, Casey Eye Institute, 3375 Southwest Terwilliger Boulevard, Portland, Oregon 97239, United States
| | - Jie Wang
- Oregon Health and Science University, Casey Eye Institute, 3375 Southwest Terwilliger Boulevard, Portland, Oregon 97239, United States
| | - Yali Jia
- Oregon Health and Science University, Casey Eye Institute, 3375 Southwest Terwilliger Boulevard, Portland, Oregon 97239, United States
| | - David Huang
- Oregon Health and Science University, Casey Eye Institute, 3375 Southwest Terwilliger Boulevard, Portland, Oregon 97239, United States
| | - Gangjun Liu
- Oregon Health and Science University, Casey Eye Institute, 3375 Southwest Terwilliger Boulevard, Portland, Oregon 97239, United States
- Address all correspondence to: Gangjun Liu, E-mail:
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236
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Liu G, Jia Y, Pechauer AD, Chandwani R, Huang D. Split-spectrum phase-gradient optical coherence tomography angiography. BIOMEDICAL OPTICS EXPRESS 2016; 7:2943-54. [PMID: 27570689 PMCID: PMC4986805 DOI: 10.1364/boe.7.002943] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 06/28/2016] [Accepted: 07/05/2016] [Indexed: 05/20/2023]
Abstract
A phase gradient angiography (PGA) method is proposed for optical coherence tomography (OCT). This method allows the use of phase information to map the microvasculature in tissue without the correction of bulk motion and laser trigger jitter induced phase artifacts. PGA can also be combined with the amplitude/intensity to improve the performance. Split-spectrum technique can further increase the signal to noise ratio by more than two times. In-vivo imaging of human retinal circulation is shown with a 70 kHz, 840 nm spectral domain OCT system and a 200 kHz, 1050 nm swept source OCT system. Four different OCT angiography methods are compared. The best performance was achieved with split-spectrum amplitude and phase-gradient angiography.
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237
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Son T, Wang B, Thapa D, Lu Y, Chen Y, Cao D, Yao X. Optical coherence tomography angiography of stimulus evoked hemodynamic responses in individual retinal layers. BIOMEDICAL OPTICS EXPRESS 2016; 7:3151-62. [PMID: 27570706 PMCID: PMC4986822 DOI: 10.1364/boe.7.003151] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 06/08/2016] [Accepted: 06/10/2016] [Indexed: 05/05/2023]
Abstract
Blood flow changes are highly related to neural activities in the retina. It has been reported that neural activity increases when flickering light stimulation of the retina is used. It is known that blood flow changes with flickering light stimulation can be altered in patients with vascular disease and that measurement of flicker-induced vasodilatation is an easily applied tool for monitoring functional microvascular alterations. However, details of distortions in retinal neurovascular coupling associated with major eye diseases are not well understood due to the limitation of existing techniques. In this study, flickering light stimulation was applied to mouse retinas to investigate stimulus evoked hemodynamic responses in individual retinal layers. A spectral domain optical coherence tomography (OCT) angiography imaging system was developed to provide dynamic mapping of hemodynamic responses in the ganglion cell layer, inner plexiform layer, outer plexiform layer and choroid layer before, during and after flickering light stimulation. Experimental results showed hemodynamic responses with different magnitudes and time courses in individual retinal layers. We anticipate that the dynamic OCT angiography of stimulus evoked hemodynamic responses can greatly foster the study of neurovascular coupling mechanisms in the retina, promising new biomarkers for retinal disease detection and diagnosis.
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Affiliation(s)
- Taeyoon Son
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Benquan Wang
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Damber Thapa
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Yiming Lu
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Yanjun Chen
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Dingcai Cao
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
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238
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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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Prentašic P, Heisler M, Mammo Z, Lee S, Merkur A, Navajas E, Beg MF, Šarunic M, Loncaric S. Segmentation of the foveal microvasculature using deep learning networks. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:75008. [PMID: 27401936 DOI: 10.1117/1.jbo.21.7.075008] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 06/16/2016] [Indexed: 05/22/2023]
Abstract
Accurate segmentation of the retinal microvasculature is a critical step in the quantitative analysis of the retinal circulation, which can be an important marker in evaluating the severity of retinal diseases. As manual segmentation remains the gold standard for segmentation of optical coherence tomography angiography (OCT-A) images, we present a method for automating the segmentation of OCT-A images using deep neural networks (DNNs). Eighty OCT-A images of the foveal region in 12 eyes from 6 healthy volunteers were acquired using a prototype OCT-A system and subsequently manually segmented. The automated segmentation of the blood vessels in the OCT-A images was then performed by classifying each pixel into vessel or nonvessel class using deep convolutional neural networks. When the automated results were compared against the manual segmentation results, a maximum mean accuracy of 0.83 was obtained. When the automated results were compared with inter and intrarater accuracies, the automated results were shown to be comparable to the human raters suggesting that segmentation using DNNs is comparable to a second manual rater. As manually segmenting the retinal microvasculature is a tedious task, having a reliable automated output such as automated segmentation by DNNs, is an important step in creating an automated output.
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Affiliation(s)
- Pavle Prentašic
- University of Zagreb, Faculty of Electrical Engineering and Computing, Unska ul. 3, Zagreb 10000, Croatia
| | - Morgan Heisler
- Simon Fraser University, Department of Engineering Science, 8888 University Drive, Burnaby, British Columbia V5A1S6, Canada
| | - Zaid Mammo
- University of British Columbia, Department of Ophthalmology and Visual Science, Eye Care Center, 2550 Willow Street, Vancouver, British Columbia V5Z 3N9, Canada
| | - Sieun Lee
- Simon Fraser University, Department of Engineering Science, 8888 University Drive, Burnaby, British Columbia V5A1S6, Canada
| | - Andrew Merkur
- University of British Columbia, Department of Ophthalmology and Visual Science, Eye Care Center, 2550 Willow Street, Vancouver, British Columbia V5Z 3N9, Canada
| | - Eduardo Navajas
- University of British Columbia, Department of Ophthalmology and Visual Science, Eye Care Center, 2550 Willow Street, Vancouver, British Columbia V5Z 3N9, Canada
| | - Mirza Faisal Beg
- Simon Fraser University, Department of Engineering Science, 8888 University Drive, Burnaby, British Columbia V5A1S6, Canada
| | - Marinko Šarunic
- Simon Fraser University, Department of Engineering Science, 8888 University Drive, Burnaby, British Columbia V5A1S6, Canada
| | - Sven Loncaric
- University of Zagreb, Faculty of Electrical Engineering and Computing, Unska ul. 3, Zagreb 10000, Croatia
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240
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Chu Z, Lin J, Gao C, Xin C, Zhang Q, Chen CL, Roisman L, Gregori G, Rosenfeld PJ, Wang RK. Quantitative assessment of the retinal microvasculature using optical coherence tomography angiography. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:66008. [PMID: 27286188 PMCID: PMC4901200 DOI: 10.1117/1.jbo.21.6.066008] [Citation(s) in RCA: 206] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 05/26/2016] [Indexed: 05/18/2023]
Abstract
Optical coherence tomography angiography (OCTA) is clinically useful for the qualitative assessment of the macular microvasculature. However, there is a need for comprehensive quantitative tools to help objectively analyze the OCT angiograms. Few studies have reported the use of a single quantitative index to describe vessel density in OCT angiograms. In this study, we introduce a five-index quantitative analysis of OCT angiograms in an attempt to detect and assess vascular abnormalities from multiple perspectives. The indices include vessel area density, vessel skeleton density, vessel diameter index, vessel perimeter index, and vessel complexity index. We show the usefulness of the proposed indices with five illustrative cases. Repeatability is tested on both a healthy case and a stable diseased case, giving interclass coefficients smaller than 0.031. The results demonstrate that our proposed quantitative analysis may be useful as a complement to conventional OCTA for the diagnosis of disease and monitoring of treatment.
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Affiliation(s)
- Zhongdi Chu
- University of Washington, Department of Bioengineering, 3720 Northeast 15th Avenue, Seattle, Washington 98006, United States
| | - Jason Lin
- University of Washington, Department of Bioengineering, 3720 Northeast 15th Avenue, Seattle, Washington 98006, United States
| | - Chen Gao
- University of Washington, Department of Bioengineering, 3720 Northeast 15th Avenue, Seattle, Washington 98006, United States
| | - Chen Xin
- University of Washington, Department of Bioengineering, 3720 Northeast 15th Avenue, Seattle, Washington 98006, United States
| | - Qinqin Zhang
- University of Washington, Department of Bioengineering, 3720 Northeast 15th Avenue, Seattle, Washington 98006, United States
| | - Chieh-Li Chen
- University of Washington, Department of Bioengineering, 3720 Northeast 15th Avenue, Seattle, Washington 98006, United States
| | - Luis Roisman
- University of Miami Miller School of Medicine, Bascom Palmer Eye Institute, 900 Northeast 17th Street, Miami, Florida 33136, United States
| | - Giovanni Gregori
- University of Miami Miller School of Medicine, Bascom Palmer Eye Institute, 900 Northeast 17th Street, Miami, Florida 33136, United States
| | - Philip J. Rosenfeld
- University of Miami Miller School of Medicine, Bascom Palmer Eye Institute, 900 Northeast 17th Street, Miami, Florida 33136, United States
| | - Ruikang K. Wang
- University of Washington, Department of Bioengineering, 3720 Northeast 15th Avenue, Seattle, Washington 98006, United States
- Address all correspondence to: Ruikang K. Wang, E-mail:
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241
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Agrawal R, Xin W, Keane PA, Chhablani J, Agarwal A. Optical coherence tomography angiography: a non-invasive tool to image end-arterial system. Expert Rev Med Devices 2016; 13:519-21. [PMID: 27176114 DOI: 10.1080/17434440.2016.1186540] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Rupesh Agrawal
- a National Healthcare Group Eye Institute , Tan Tock Seng Hospital , Singapore.,b Department of Medical Retina , Moorfields Eye Hospital NHS Foundation Trust , London , UK.,c Institute of Ophthalmology , University College London , London , UK
| | - Wei Xin
- a National Healthcare Group Eye Institute , Tan Tock Seng Hospital , Singapore
| | - Pearse A Keane
- b Department of Medical Retina , Moorfields Eye Hospital NHS Foundation Trust , London , UK.,c Institute of Ophthalmology , University College London , London , UK
| | - Jay Chhablani
- d Department of Vitreoretina , L V Prasad Eye Institute , Hyderabad , India
| | - Aniruddha Agarwal
- e Stanley M. Truhlsen Eye Institute , University of Nebraska Medical Center , Omaha , Nebraska , USA
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242
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Kam J, Zhang Q, Lin J, Liu J, Wang RK, Rezaei K. Optical coherence tomography based microangiography findings in hydroxychloroquine toxicity. Quant Imaging Med Surg 2016; 6:178-83. [PMID: 27190770 DOI: 10.21037/qims.2016.01.01] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Optical coherence tomography based microangiography (OMAG) is a new, non-invasive imaging modality capable of providing three dimentional (3D) retinal and choroidal microvascular maps without a need for exogenous dye. In this study, we evaluated the retinal and choroidal microvascular architecture of the macula in a patient with hydroxychloroquine (HCQ) toxicity using OMAG. Detailed microvascular information of the retina and the underlying choroid showed loss of parafoveal outer retinal vasculature with sparing of the central fovea vasculature.
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Affiliation(s)
- Jason Kam
- 1 Department of Ophthalmology, 2 Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Qinqin Zhang
- 1 Department of Ophthalmology, 2 Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Jason Lin
- 1 Department of Ophthalmology, 2 Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Jin Liu
- 1 Department of Ophthalmology, 2 Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Ruikang K Wang
- 1 Department of Ophthalmology, 2 Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Kasra Rezaei
- 1 Department of Ophthalmology, 2 Department of Bioengineering, University of Washington, Seattle, WA, USA
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243
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Wang RK, Zhang A, Choi WJ, Zhang Q, Chen CL, Miller A, Gregori G, Rosenfeld PJ. Wide-field optical coherence tomography angiography enabled by two repeated measurements of B-scans. OPTICS LETTERS 2016; 41:2330-3. [PMID: 27176995 PMCID: PMC5266531 DOI: 10.1364/ol.41.002330] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Optical coherence tomography angiography (OCTA) has increasingly become clinically important, particularly in ophthalmology. However, the field of view (FOV) for current OCTA imaging is severely limited due to A-scan rates that can be afforded by current clinical systems and, more importantly, the requirement of a repeated scanning protocol. This Letter evaluates the possibility of using only two repeated B-scans for OCTA for the purpose of an increased FOV. The effect of repeated numbers on the OCTA result is discussed through experiments on an animal model in vivo and evaluated using quantitative metrics for image quality. Demonstrated through in vivo imaging of a pathological human eye, we show that optical microangiography-based OCTA with two repeated B-scans can provide wide-field angiography up to 12×12 mm with clinically acceptable image quality.
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Affiliation(s)
- Ruikang K. Wang
- University of Washington, Department of Bioengineering, Seattle, Washington
- Corresponding author:
| | - Anqi Zhang
- University of Washington, Department of Bioengineering, Seattle, Washington
| | - Woo June Choi
- University of Washington, Department of Bioengineering, Seattle, Washington
| | - Qinqin Zhang
- University of Washington, Department of Bioengineering, Seattle, Washington
| | - Chieh-Li Chen
- University of Washington, Department of Bioengineering, Seattle, Washington
| | - Andrew Miller
- University of Miami Miller School of Medicine, Bascom Palmer Eye Institute, Miami, Florida
| | - Giovanni Gregori
- University of Miami Miller School of Medicine, Bascom Palmer Eye Institute, Miami, Florida
| | - Philip J. Rosenfeld
- University of Miami Miller School of Medicine, Bascom Palmer Eye Institute, Miami, Florida
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244
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Optic Disc Perfusion in Primary Open Angle and Normal Tension Glaucoma Eyes Using Optical Coherence Tomography-Based Microangiography. PLoS One 2016; 11:e0154691. [PMID: 27149261 PMCID: PMC4858256 DOI: 10.1371/journal.pone.0154691] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 04/18/2016] [Indexed: 01/14/2023] Open
Abstract
Purpose To investigate optic disc perfusion differences in normal, primary open-angle glaucoma (POAG), and normal tension glaucoma (NTG) eyes using optical microangiography (OMAG) based optical coherence tomography (OCT) angiography technique. Design Cross-sectional, observational study. Subjects Twenty-eight normal, 30 POAG, and 31 NTG subjects. Methods One eye from each subject was scanned with a 68 kHz Cirrus HD-OCT 5,000-based OMAG prototype system centered at the optic nerve head (ONH) (Carl Zeiss Meditec Inc, Dublin, CA). Microvascular images were generated from the OMAG dataset by detecting the differences in OCT signal between consecutive B-scans. The pre-laminar layer (preLC) was isolated by a semi-automatic segmentation program. Main Outcome Measures Optic disc perfusion, quantified as flux, vessel area density, and normalized flux (flux normalized by the vessel area) within the ONH. Results Glaucomatous eyes had significantly lower optic disc perfusion in preLC in all three perfusion metrics (p<0.0001) compared to normal eyes. The visual field (VF) mean deviation (MD) and pattern standard deviation (PSD) were similar between the POAG and NTG groups, and no differences in optic disc perfusion were observed between POAG and NTG. Univariate analysis revealed significant correlation between optic disc perfusion and VF MD, VF PSD, and rim area in both POAG and NTG groups (p≤0.0288). However, normalized optic disc perfusion was correlated with some structural measures (retinal nerve fiber layer thickness and ONH cup/disc ratio) only in POAG eyes. Conclusions Optic disc perfusion detected with OMAG was significantly reduced in POAG and NTG groups compared to normal controls, but no difference was seen between POAG and NTG groups with similar levels of VF damage. Disc perfusion was significantly correlated with VF MD, VF PSD, and rim area in glaucomatous eyes. Vascular changes at the optic disc as measured using OMAG may provide useful information for diagnosis and monitoring of glaucoma.
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245
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Raghunathan R, Singh M, Dickinson ME, Larin KV. Optical coherence tomography for embryonic imaging: a review. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:50902. [PMID: 27228503 PMCID: PMC4881290 DOI: 10.1117/1.jbo.21.5.050902] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 04/25/2016] [Indexed: 05/18/2023]
Abstract
Embryogenesis is a highly complex and dynamic process, and its visualization is crucial for understanding basic physiological processes during development and for identifying and assessing possible defects, malformations, and diseases. While traditional imaging modalities, such as ultrasound biomicroscopy, micro-magnetic resonance imaging, and micro-computed tomography, have long been adapted for embryonic imaging, these techniques generally have limitations in their speed, spatial resolution, and contrast to capture processes such as cardiodynamics during embryogenesis. Optical coherence tomography (OCT) is a noninvasive imaging modality with micrometer-scale spatial resolution and imaging depth up to a few millimeters in tissue. OCT has bridged the gap between ultrahigh resolution imaging techniques with limited imaging depth like confocal microscopy and modalities, such as ultrasound sonography, which have deeper penetration but poorer spatial resolution. Moreover, the noninvasive nature of OCT has enabled live imaging of embryos without any external contrast agents. We review how OCT has been utilized to study developing embryos and also discuss advances in techniques used in conjunction with OCT to understand embryonic development.
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Affiliation(s)
- Raksha Raghunathan
- University of Houston, Department of Biomedical Engineering, 3517 Cullen Boulevard, Room 2027, Houston, Texas 77204-5060, United States
| | - Manmohan Singh
- University of Houston, Department of Biomedical Engineering, 3517 Cullen Boulevard, Room 2027, Houston, Texas 77204-5060, United States
| | - Mary E. Dickinson
- Baylor College of Medicine, Department of Molecular Physiology and Biophysics, One Baylor Plaza- BCM335, Houston, Texas 77030, United States
| | - Kirill V. Larin
- University of Houston, Department of Biomedical Engineering, 3517 Cullen Boulevard, Room 2027, Houston, Texas 77204-5060, United States
- Baylor College of Medicine, Department of Molecular Physiology and Biophysics, One Baylor Plaza- BCM335, Houston, Texas 77030, United States
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246
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Wei W, Xu J, Baran U, Song S, Qin W, Qi X, Wang RK. Intervolume analysis to achieve four-dimensional optical microangiography for observation of dynamic blood flow. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:36005. [PMID: 26968387 PMCID: PMC5996864 DOI: 10.1117/1.jbo.21.3.036005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 02/11/2016] [Indexed: 05/19/2023]
Abstract
We demonstrate in vivo volumetric optical microangiography at ∼ 200 volumes/s by the use of 1.6 MHz Fourier domain mode-locking swept source optical coherence tomography and an effective 36 kHz microelectromechanical system (MEMS) scanner. We propose an intervolume analysis strategy to contrast the dynamic blood flow signal from the static tissue background. The proposed system is demonstrated by imaging cerebral blood flow in mice in vivo. For the first time, imaging speed, sensitivity, and temporal resolution become possible for a direct four-dimensional observation of microcirculations within live body parts.
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Affiliation(s)
- Wei Wei
- University of Washington, Department of Bioengineering, 3720 15th Avenue NE, Seattle, Washington 98195, United States
| | - Jingjiang Xu
- University of Washington, Department of Bioengineering, 3720 15th Avenue NE, Seattle, Washington 98195, United States
| | - Utku Baran
- University of Washington, Department of Bioengineering, 3720 15th Avenue NE, Seattle, Washington 98195, United States
- University of Washington, Department of Electrical Engineering, 185 Stevens Way, Seattle, Washington 98195, United States
| | - Shaozhen Song
- University of Washington, Department of Bioengineering, 3720 15th Avenue NE, Seattle, Washington 98195, United States
| | - Wan Qin
- University of Washington, Department of Bioengineering, 3720 15th Avenue NE, Seattle, Washington 98195, United States
| | - Xiaoli Qi
- University of Washington, Department of Bioengineering, 3720 15th Avenue NE, Seattle, Washington 98195, United States
| | - Ruikang K. Wang
- University of Washington, Department of Bioengineering, 3720 15th Avenue NE, Seattle, Washington 98195, United States
- Address all correspondence to: Ruikang K. Wang, E-mail:
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247
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Li P, Cheng Y, Zhou L, Pan C, Ding Z, Li P. Single-shot angular compounded optical coherence tomography angiography by splitting full-space B-scan modulation spectrum for flow contrast enhancement. OPTICS LETTERS 2016; 41:1058-61. [PMID: 26974115 DOI: 10.1364/ol.41.001058] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We proposed a single-shot spatial angular compounded optical coherence tomography angiography (AC-Angio-OCT) for blood flow contrast enhancement. By encoding incident angles in B-scan modulation frequencies and splitting the modulation spectrum in the spatial frequency domain, angle-resolved independent subangiograms were obtained and compounded to improve the flow contrast. A full space of the spatial frequency domain allows a wide modulation spectrum. To get access to the full space of the spatial frequency domain and avoid the complex-conjugate ambiguity of the modulation spectrum, a complex-valued OCT spectral interferogram was retrieved by removing one of the conjugate terms in the depth space. To validate the proposed concept, both flow phantom and live animal experiments were performed. The proposed AC-Angio-OCT offers a ∼50% decrease of misclassification errors, and an improved flow contrast and vessel connectivity, which contributes to the interpretation of OCT angiograms.
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248
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Gorczynska I, Migacz JV, Zawadzki RJ, Capps AG, Werner JS. Comparison of amplitude-decorrelation, speckle-variance and phase-variance OCT angiography methods for imaging the human retina and choroid. BIOMEDICAL OPTICS EXPRESS 2016; 7:911-42. [PMID: 27231598 PMCID: PMC4866465 DOI: 10.1364/boe.7.000911] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 02/03/2016] [Accepted: 02/12/2016] [Indexed: 05/18/2023]
Abstract
We compared the performance of three OCT angiography (OCTA) methods: speckle variance, amplitude decorrelation and phase variance for imaging of the human retina and choroid. Two averaging methods, split spectrum and volume averaging, were compared to assess the quality of the OCTA vascular images. All data were acquired using a swept-source OCT system at 1040 nm central wavelength, operating at 100,000 A-scans/s. We performed a quantitative comparison using a contrast-to-noise (CNR) metric to assess the capability of the three methods to visualize the choriocapillaris layer. For evaluation of the static tissue noise suppression in OCTA images we proposed to calculate CNR between the photoreceptor/RPE complex and the choriocapillaris layer. Finally, we demonstrated that implementation of intensity-based OCT imaging and OCT angiography methods allows for visualization of retinal and choroidal vascular layers known from anatomic studies in retinal preparations. OCT projection imaging of data flattened to selected retinal layers was implemented to visualize retinal and choroidal vasculature. User guided vessel tracing was applied to segment the retinal vasculature. The results were visualized in a form of a skeletonized 3D model.
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Affiliation(s)
- Iwona Gorczynska
- Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
- Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun 87-100, Poland
| | - Justin V. Migacz
- Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - Robert J. Zawadzki
- Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - Arlie G. Capps
- Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
- Physics Division, Lawrence Livermore National Laboratory Livermore, CA 94550, USA
| | - John S. Werner
- Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
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249
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Baran U, Wang RK. Review of optical coherence tomography based angiography in neuroscience. NEUROPHOTONICS 2016; 3:010902. [PMID: 26835484 PMCID: PMC4719095 DOI: 10.1117/1.nph.3.1.010902] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 12/14/2015] [Indexed: 05/09/2023]
Abstract
The brain is a complex ecosystem, consisting of multiple layers and tissue compartments. To facilitate the understanding of its function and its response to neurological insults, a fast in vivo imaging tool with a micron-level resolution, which can provide a field of view at a few millimeters, is desirable. Optical coherence tomography (OCT) is a noninvasive method for imaging three-dimensional biological tissues with high resolution ([Formula: see text]) and without a need for contrast agents. Recent development of OCT-based angiography has started to shed some new light on cerebral hemodynamics in neuroscience. We give an overview of the recent developments of OCT-based imaging techniques for neuroscience applications in rodents. We summarize today's technological alternatives for OCT-based angiography for neuroscience and provide a discussion of challenges and opportunities. Moreover, a summary of OCT angiography studies for stroke, traumatic brain injury, and subarachnoid hemorrhage cases on rodents is provided.
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Affiliation(s)
- Utku Baran
- University of Washington, Department of Bioengineering, 3720 15th Avenue NE, Seattle, Washington 98195, United States
- University of Washington, Department of Electrical Engineering, 185 Stevens Way, Seattle, Washington 98195, United States
| | - Ruikang K. Wang
- University of Washington, Department of Bioengineering, 3720 15th Avenue NE, Seattle, Washington 98195, United States
- Address all correspondence to: Ruikang K. Wang, E-mail:
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