Accurate OCT-angiography Interpretation - Detection and Exclusion of Artifacts

Abstract

Background Optical coherence tomography angiography (OCTA) provides, non-invasively, a three-dimensional visualization of the microvasculature of the retina and choroid. However, image artifacts may occur in OCTA and have an impact on clinical interpretation. The aim of this article is to describe image artifacts of OCTA and to present a nomenclature. Methods OCTA examinations were performed with the AngioPlex™ OCTA-technology in combination with the CIRRUS HD-OCT 5000 (Carl Zeiss Meditec, Inc., Dublin, USA) as well as with the PlexElite 9000 (Carl Zeiss Meditec, Inc., Dublin, USA). Typical artifacts identified in the OCTA images are described and their causes are explained. Results There are three main groups of artifacts that can be distinguished: (a) artifacts that are inherent in the OCTA technology and occur with all types of devices (projection artifacts, masking, unmasking, loss of signal); (b) artifacts caused by data and image processing algorithms and whose frequency or severity may depend on the device type used (segmentation artifacts, duplications of vessels); (c) motion artifacts that vary in frequency and severity depending on the type of device used, as different methods (e.g., eye tracker) are used to reduce them. The occurrence of artifacts is also dependent on patient cooperation, the clarity of the optical media, and the pathology of the retina. Conclusion As in any other imaging method, artifacts also occur in OCTA images. Nevertheless, qualitative assessment of OCTA images is almost always possible and provides indispensable findings on the morphology and perfusion status of the retina and choroid. A good knowledge of possible artifacts, and a critical analysis of the complete OCTA data set, allows a correct interpretation and is essential for making a precise clinical diagnosis.