Impact of A-Scan Rate on Image Quality and Acquisition Time in OCT

Abstract

Purpose: This study aims to examine the impact of the A-scan rate in optical coherence tomography (OCT) on scan quality and acquisition time.

Methods: Two horizontal OCT scans per scan rate (20, 85, 125 kHz) of the right eye were captured with the same OCT device (Spectralis SHIFT, HRA + OCT, Heidelberg Engineering GmbH, Heidelberg, Germany) of patients who presented to the inherited retinal dystrophies consultation, thus predominantly challenging patients due to reduced fixation ability. Scan quality was measured by the Q score, a signal-to-noise-ratio (SNR). Acquisition time was measured in seconds.

Results: Fifty-one patients were included in the study. The highest quality was seen for an A-scan rate of 20 kHz (44.49 dB), succeeded by scans of an A-Scan rate of 85 kHz (38.53 dB) and of 125 kHz (36.65 dB). Differences in scan quality between the various A-scan rates were statistically significant. The acquisition time seen for an A-scan rate of 20 kHz (6.45 s) was significantly longer than those seen for an A-Scan rate of 85 kHz (1.51 s) and of 125 kHz (1.69 s).

Conclusion: An A-scan rate of 20 kHz resulted in a significantly higher scan quality but also a significantly longer acquisition time compared to scan rates of 85 kHz and 125 kHz. Differences between an A-scan rate of 85 kHz and 125 kHz were marginal.

Keywords: OCT acquisition time; OCT scan quality; Optical coherence tomography; Spectralis SHIFT OCT; inherited retinal dystrophies.