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Qinqin Zhang, Anqi Zhang, Cecilia S Lee, Aaron Lee, Luiz Roisman, Giovanni Gregori, Mary K Durbin, Lin An, Paul F Stetson, Philip J Rosenfeld, Ruikang K Wang; OCT-based angiography of choroidal neovascularization by removing projection artifacts. Invest. Ophthalmol. Vis. Sci. 201657(12):.
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© 2017 Association for Research in Vision and Ophthalmology.
To accurately visualize choroidal neovascularization (CNV) and its treatment response by projection artifact removed OCT-based angiography (OCTA)
A total of 30 subjects with 40 eyes diagnosed with CNV were recruited and imaged by a swept-source OCTA (SS-OCTA) prototype system. Twenty eyes underwent treatment of CNV between 2013 and 2015. Six patients were followed by OCTA imaging before and after treatment. 3D angiography was generated using optical microangiography (OMAG) algorithm that utilizes full complex OCT signals. Enface angiograms were obtained by maximum intensity projection from segmented volumes. CNV was visualized by the enface images generated from the outer retinal avascular slab (ORAS), from the outer nuclear layer to the Bruch’s membrane. A PAR algorithm was applied on ORAS to remove projection artifacts from retinal circulations. CNVs were characterized in size, neovascular density, and concurrent presence of subretinal and/or intraretinal fluids. In 6 patients, the size and VD of CNVs were compared before and after anti-VEGF treatment of CNVs. Concurrent FA/ICGA were compared for cross validation of the findings from OMAG images
The application of PAR algorithm on ORAS delineated CNV lesion effectively on all cases examined, providing more accurate and clearer lesion. Lesion size and neo-VD were measured based on artifact-free OMAG images. CNV VD reduction was observed in all six patients after treatment. In five patients, the size of CNV lesion decreased. One of six patients showed a slight increase in lesion size but a decrease in VD
OCTA implemented by OMAG algorithm with removal of projection artifacts improves visualization of CNVs and can allow for more accurate quantitative evaluation of CNVs than without the algorithm. Thus this algorithm may be a useful tool in interpreting OCTA images of CNVs that can complement current standard imaging modalities such as FA
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Figure1 FA, ICGA and OMAG images of a 77-year-old male diagnosed with CNV in left eye. A and B early/late phase of FA; C/D early/late phase of ICGA. E/ I: cross-sectional OCT image/color-coded image overlaid with flow signals before (middle) and after (bottom) treatment. F/ J: OMAG images of ORAS slab without artifact removal. G/ K: artifact-removed OMAG images after applying PAR algorithm. H/I: Color-coded CNV and choroidal OMAG images. The size of OMAG images is 3x3 mm
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