Image Artifacts in Optical Coherence Angiography

Abstract

To describe image artifacts of optical coherence tomography angiography (OCTA) and their underlying causative mechanisms. To establish a common vocabulary for the artifacts observed.

Methods

The methods by which OCTA images are acquired, generated and displayed are reviewed as are the mechanisms by which each or all of these methods can produce extraneous image information. A common set of terminology is proposed and used.

Results

OCTA uses motion contrast to image blood flow and thereby images the vasculature without the need for a contrast agent. Artifacts are very common and can arise from the OCT image acquisition, intrinsic characteristics of the eye, eye motion, or image processing and display strategies. OCT image acquisition for angiography takes more time than simple structural scans and necessitates trade-offs in flow resolution, scan quality, and speed. An important set of artifacts are projection artifacts in which images of blood vessels appear at erroneous locations. Image processing used for OCTA can alter vascular appearance through segmentation defects and because of image display strategies can give false impressions of the density and location of vessels. Eye motion leads to discontinuities in displayed data. OCTA artifacts can be detected by interactive evaluation of the images.

Conclusions

Image artifacts are common, and can lead to incorrect interpretations of OCTA images. Because of the quantity of data available and the potential for artifacts, physician interaction in viewing the image data will be required, much like what happens in modern radiology practice.