Projection Artifact Removal Improves Visualization and Quantitation of Macular Neovascularization Imaged by Optical Coherence Tomography Angiography

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 ≥1 eye. Methods Patients were imaged using either a swept-source OCTA prototype system or a spectral-domain 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. After removal of the projection artifacts from the OCTA images, we assessed the size and vascularity of the MNV. Concurrent fluorescein angiography and indocyanine green angiography 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 inhibitors. After 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 5 eyes after treatment, and in 4 eyes, the size of the MNV decreased. One of 5 patients showed a slight increase in lesion size but a decrease in vascular density. Conclusions Using the OMAG algorithm, OCTA imaging of MNV combined with removal of projection artifacts resulted in improved visualization and measurement of the neovascular lesions. Thus, OMAG with projection artifact removal should be useful for assessing the response of MNV to treatment using OCTA imaging.