scholarly journals Automatic Segmentation and Classification Methods Using Optical Coherence Tomography Angiography (OCTA): A Review and Handbook

2021 ◽  
Vol 11 (20) ◽  
pp. 9734
Author(s):  
Kristen M. Meiburger ◽  
Massimo Salvi ◽  
Giulia Rotunno ◽  
Wolfgang Drexler ◽  
Mengyang Liu
Keyword(s):  
Optical Coherence Tomography ◽  
Optical Coherence Tomography Angiography ◽  
Automatic Segmentation ◽  
Clinical Applications ◽  
Optical Coherence ◽  
Classification Methods ◽  
Non Invasive ◽  
Comparison Of Techniques ◽  
Automated Algorithms ◽  
Insight Into

Optical coherence tomography angiography (OCTA) is a promising technology for the non-invasive imaging of vasculature. Many studies in literature present automated algorithms to quantify OCTA images, but there is a lack of a review on the most common methods and their comparison considering multiple clinical applications (e.g., ophthalmology and dermatology). Here, we aim to provide readers with a useful review and handbook for automatic segmentation and classification methods using OCTA images, presenting a comparison of techniques found in the literature based on the adopted segmentation or classification method and on the clinical application. Another goal of this study is to provide insight into the direction of research in automated OCTA image analysis, especially in the current era of deep learning.

scholarly journals Automatic segmentation of foveal avascular zone based on adaptive watershed algorithm in retinal optical coherence tomography angiography images

2021 ◽  
Author(s):  
Jian Liu ◽  
Shixin Yan ◽  
Nan Lu ◽  
Dongni Yang ◽  
Chunhui Fan ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Healthy Subjects ◽  
Optical Coherence Tomography Angiography ◽  
Automatic Segmentation ◽  
Qualitative Evaluation ◽  
Foveal Avascular Zone ◽  
Watershed Algorithm ◽  
Strong Positive Correlation ◽  
Optical Coherence ◽  
Avascular Zone

The size and shape of the foveal avascular zone (FAZ) have a strong positive correlation with several vision-threatening retinovascular diseases. The identification, segmentation and analysis of FAZ are of great significance to clinical diagnosis and treatment. We presented an adaptive watershed algorithm to automatically extract FAZ from retinal optical coherence tomography angiography (OCTA) images. For the traditional watershed algorithm, “over-segmentation” is the most common problem. FAZ is often incorrectly divided into multiple regions by redundant “dams”. This paper analyzed the relationship between the “dams” length and the maximum inscribed circle radius of FAZ, and proposed an adaptive watershed algorithm to solve the problem of “over-segmentation”. Here, 132 healthy retinal images and 50 diabetic retinopathy (DR) images were used to verify the accuracy and stability of the algorithm. Three ophthalmologists were invited to make quantitative and qualitative evaluations on the segmentation results of this algorithm. The quantitative evaluation results show that the correlation coefficients between the automatic and manual segmentation results are 0.945 (in healthy subjects) and 0.927 (in DR patients), respectively. For qualitative evaluation, the percentages of “perfect segmentation” (score of 3) and “good segmentation” (score of 2) are 99.4% (in healthy subjects) and 98.7% (in DR patients), respectively. This work promotes the application of watershed algorithm in FAZ segmentation, making it a useful tool for analyzing and diagnosing eye diseases.

scholarly journals Optical coherence tomography angiography of foveal neovascularisation in proliferative diabetic retinopathy

2019 ◽  
Vol 12 (8) ◽  
pp. e230382
Author(s):  
Deven Dhurandhar ◽  
Padmaja Kumari Rani
Keyword(s):  
Optical Coherence Tomography ◽  
Diabetic Retinopathy ◽  
Proliferative Diabetic Retinopathy ◽  
Optical Coherence Tomography Angiography ◽  
Imaging Modality ◽  
Diabetic Macular Oedema ◽  
Hypertensive Retinopathy ◽  
Optical Coherence ◽  
Non Invasive

A 52-year-old man, a known case of type 2 diabetes mellitus and hypertension, who presented to us with bilateral diminution of vision since 1 year. He was diagnosed as a case of bilateral proliferative diabetic retinopathy and hypertensive retinopathy. A non-invasive imaging modality, optical coherence tomography angiography (OCTA), detected foveal neovascularisation in a background of diffuse diabetic macular oedema which would have been obscured by other investigations like fluorescein angiography.

scholarly journals Optical coherence tomography angiography: a non-invasive tool to image end-arterial system

2016 ◽  
Vol 13 (6) ◽  
pp. 519-521 ◽  
Author(s):  
Rupesh Agrawal ◽  
Wei Xin ◽  
Pearse A. Keane ◽  
Jay Chhablani ◽  
Aniruddha Agarwal
Keyword(s):  
Optical Coherence Tomography ◽  
Optical Coherence Tomography Angiography ◽  
Arterial System ◽  
Optical Coherence ◽  
Non Invasive

scholarly journals Optical Coherence Tomography Angiography in Neurodegenerative Disorders

2020 ◽  
Vol 9 (6) ◽  
pp. 1706 ◽  
Author(s):  
Marco Pellegrini ◽  
Aldo Vagge ◽  
Lorenzo Ferro Desideri ◽  
Federico Bernabei ◽  
Giacinto Triolo ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Optical Coherence Tomography ◽  
Neurodegenerative Disorders ◽  
Optical Coherence Tomography Angiography ◽  
Imaging Modality ◽  
Optical Coherence ◽  
Microvascular Damage ◽  
Future Directions ◽  
Non Invasive ◽  
Retinal Microcirculation

Retinal microcirculation shares similar features with cerebral small blood vessels. Thus, the retina may be considered an accessible ‘window’ to detect the microvascular damage occurring in the setting of neurodegenerative disorders. Optical coherence tomography angiography (OCT-A) is a non-invasive imaging modality providing depth resolved images of blood flow in the retina, choroid, and optic nerve. In this review, we summarize the current literature on the application of OCT-A in glaucoma and central nervous system conditions such as Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis. Future directions aiming at evaluating whether OCT-A can be an additional biomarker for the early diagnosis and monitoring of neurodegenerative disorders are also discussed.

scholarly journals Automatic Visual Acuity Estimation by Means of Computational Vascularity Biomarkers Using Oct Angiographies

Sensors ◽  
2019 ◽  
Vol 19 (21) ◽  
pp. 4732
Author(s):  
Macarena Díaz ◽  
Marta Díez-Sotelo ◽  
Francisco Gómez-Ulla ◽  
Jorge Novo ◽  
Manuel Francisco G. Penedo ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Visual Acuity ◽  
Optical Coherence Tomography Angiography ◽  
Vision Loss ◽  
Eye Diseases ◽  
Optical Coherence ◽  
Non Invasive ◽  
Foveal Region ◽  
Image Modality

Optical Coherence Tomography Angiography (OCTA) constitutes a new non-invasive ophthalmic image modality that allows the precise visualization of the micro-retinal vascularity that is commonly used to analyze the foveal region. Given that there are many systemic and eye diseases that affect the eye fundus and its vascularity, the analysis of that region is crucial to diagnose and estimate the vision loss. The Visual Acuity (VA) is typically measured manually, implying an exhaustive and time-consuming procedure. In this work, we propose a method that exploits the information of the OCTA images to automatically estimate the VA with an accurate error of 0.1713.

scholarly journals Optical coherence tomography angiography in diabetic retinopathy: a review of current applications

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Kai Yuan Tey ◽  
Kelvin Teo ◽  
Anna C. S. Tan ◽  
Kavya Devarajan ◽  
Bingyao Tan ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Diabetic Retinopathy ◽  
Optical Coherence Tomography Angiography ◽  
Vision Loss ◽  
Imaging Modality ◽  
Anterior Segment ◽  
Foveal Avascular Zone ◽  
Imaging Method ◽  
Optical Coherence ◽  
Non Invasive

Abstract Background Diabetic retinopathy (DR) is a leading cause of vision loss in adults. Currently, the standard imaging technique to monitor and prognosticate DR and diabetic maculopathy is dye-based angiography. With the introduction of optical coherence tomography angiography (OCTA), it may serve as a potential rapid, non-invasive imaging modality as an adjunct. Main text Recent studies on the role of OCTA in DR include the use of vascular parameters e.g., vessel density, intercapillary spacing, vessel diameter index, length of vessels based on skeletonised OCTA, the total length of vessels, vascular architecture and area of the foveal avascular zone. These quantitative measures may be able to detect changes with the severity and progress of DR for clinical research. OCTA may also serve as a non-invasive imaging method to detect diabetic macula ischemia, which may help predict visual prognosis. However, there are many limitations of OCTA in DR, such as difficulty in segmentation between superficial and deep capillary plexus; and its use in diabetic macula edema where the presence of cystic spaces may affect image results. Future applications of OCTA in the anterior segment include detection of anterior segment ischemia and iris neovascularisation associated with proliferative DR and risk of neovascular glaucoma. Conclusion OCTA may potentially serve as a useful non-invasive imaging tool in the diagnosis and monitoring of diabetic retinopathy and maculopathy in the future. Future studies may demonstrate how quantitative OCTA measures may have a role in detecting early retinal changes in patients with diabetes.

scholarly journals A pilot study investigating anterior segment optical coherence tomography angiography as a non-invasive tool in evaluating corneal vascularisation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hon Shing Ong ◽  
Kai Yuan Tey ◽  
Mengyuan Ke ◽  
Bingyao Tan ◽  
Jacqueline Chua ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Optical Coherence Tomography Angiography ◽  
Objective Assessment ◽  
Anterior Segment ◽  
Optical Coherence ◽  
Non Invasive ◽  
Imaging Tool ◽  
Model Study ◽  
Animal Model Study ◽  
Endothelial Growth Factor

AbstractThe current assessment of corneal vascularisation (CV) relies on slit-lamp examination, which may be subjective. Dye-based angiographies, like indocyanine green angiography (ICGA), allows for good visualisation of anterior segment blood vessels. However, ICGA is invasive and can be associated with systemic adverse effects. Anterior segment optical coherence tomography angiography (AS-OCTA) is a non-invasive tool that has been shown to successfully delineate CV. However, there are no previous studies that have reported if AS-OCTA can determine CV stage and activity. We used an established CV model in rabbits to examine serial AS-OCTA scans of CV development and regression following treatment with anti-vascular endothelial growth factor. We compared AS-OCTA derived vascular measurements to that of ICGA determined vessel leakage and CV staging. Our results showed that AS-OCTA vessel densities and vessel branch area significantly correlated with the severity of CV based on ICGA (all p ≤ 0.05). We also found that AS-OCTA vessel densities correlated with ICGA vessel leakage time, following an inverse linear relationship (r2 = − 0.726, p < 0.01). Changes in aqueous levels of CXCL-12 and PIGF cytokines significantly correlated with AS-OCTA vessel densities (r2 = 0.736 and r2 = 0.731 respectively, all p < 0.05). In summary, we found that AS-OCTA derived vessel parameters may be useful for assessing CV severity, while vessel density correlates with CV activity and leakage. Thus, our pilot animal model study suggests that AS-OCTA may be a useful non-invasive imaging tool to provide objective assessment of CV to examine progression or response in treatment, which requires confirmation in clinical studies.

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