Minimizing projection artifacts for accurate presentation of choroidal neovascularization in OCT micro-angiography

Abstract

Current optical coherence tomography (OCT) based microangiography is prone to a projection (or tailing) effect due to the high scattering property of blood within overlying patent vessels, creating artifacts that interfere with the interpretation of retinal angiographic results. In this work, the projection effect in OCT micro-angiography is examined and its causality is explained by strong light scattering and photon propagation within blood. A simple practical approach is then introduced to minimize these artifacts presented in the outer retinal avascular space, especially useful for examining clinical cases with choroidal neovascularization (CNV). Demonstrated through in-vivo human posterior eye imaging of healthy and CNV subjects, the proposed method is shown effective to eliminate the projection artifacts in outer retinal space of OCT micro-angiography, resulting in better visualization of the pathological neovascularization when compared with the current common approaches. In addition, it is also shown that the proposed method is applicable to minimize the projection artifacts appearing in deep retinal layers.

In vivo label-free lymphangiography of cutaneous lymphatic vessels in human burn scars using optical coherence tomography

“…2(c) and 2(d). Characteristically, there is also high decorrelation at depths below the blood vessel due to the high scattering nature of blood, as described in Ref [21]. Visually, this artifact appears as axial 'tails' of decorrelation below the blood vessels, such as that shown in the inset of Fig.…”

“…This can lead to the misidentification of a blood vessel as a lymphatic vessel by intensity-based methods. Additional differentiation of vessels would be required, potentially using the characteristic axial 'tails' of decorrelated speckle found below blood vessels, as noted in Ref [21].…”

Quantitative characteristics of sickle cell retinopathy in optical coherence tomography angiography

“…ReVue software utilizes SSADA algorithm for OCTA construction, with integrated motion correction algorithm. Potential incorporation of removal algorithm of projection artifacts [34,35] may further improve the OCTA image quality.…”

Advances in Optical Coherence Tomography Angiography

“…Automated software can remove this artifact so abnormal neovascularization in the outer retina can be more easily seen. [13][14][15] Finally, the deeper choroidal vessels appear dark (instead of white) due to fringe washout and a stromal decorrelation signal is seen on the OCT angiogram. …”