Abstract
Purpose :
The ideal tradeoff between A-scan rate, acquisition time and image quality for optical coherence tomography (OCT) and OCT-Angiography (OCTA) is currently unknown. The purpose of this study was to compare the image quality and acquisition time between the variable scanning speed SPECTRALIS® SHIFT technology (spectral domain, 20 kHz, 85 kHz, 125 kHz, and 250 kHz) and 100 kHz swept source OCTA.
Methods :
We conducted this cross-sectional observational study from August 2021 to November 2021 at Massachusetts Eye and Ear enrolling 20 healthy eyes. After obtaining written informed consent, patients were imaged on the 100 kHz PLEX® Elite 9000 (Carl Zeiss) using 6 mm x 6 mm angiogram centered on fovea, followed by Heidelberg SPECTRALIS® SHIFT technology (OCTA mode, Scout 20 preset at 85 kHz, 125 kHz, and 250 kHz). The latter gives standard 6.4 mm x 6.4 mm angiogram superimposed on the structural en-face images.
Results :
The mean acquisition time were 31.1 seconds for 100 kHz PLEX®, 36 seconds for 85 kHz, 33.8 seconds for 125 kHz and 30.5 seconds for 250 kHz SHIFT technology. The OCTA image resolution was similar for the PLEX® 6 mm x 6 mm image at 1024 x 1024 pixels, while 1016 x 1016 pixels for the 6.4 mm x 6.4 mm image from SHIFT technology. The B-scan image quality and details were comparable between the two devices (Figure 1) but there was better delineation of microvasculature on PLEX® OCTA. Subjectively, there was evidence of higher motion artifacts on all layers and scan speed angiograms from SHIFT technology versus PLEX® due to better iris tracking software in the latter. We also noted progressive decrease in signal to noise ratio with increasing speeds for OCTA images acquired via SHIFT technology (Figure 2).
Conclusions :
In this preliminary study we noted that higher scanning speed may not necessarily result in better image quality or significantly shorter scanning time. Although the image resolution was comparable, there were visible difference in capillary details, motion artifacts, etc. between the two devices. Future studies on different scan speed angiograms can open doors to their varied clinical application in patient specific pathology and media opacity status.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.