Purpose:
To determine the motion compensation capability of retinal tracking software implemented on Cirrus HD-OCT.
Methods:
Twenty (20) subjects with various diseases including age-related macular degeneration (AMD), branch retinal vein occlusion (BRVO) and diabetic macular edema (DME) were scanned using a prototype version of the Cirrus HD-OCT software that implements retinal tracking to compensate for subject motion during the scan. Two Optic Disc 200x200 scans with tracking and two scans without tracking were obtained on each subject for a total of 80 cube scans. The motion compensation capability of the software was evaluated by visual inspection of the OCT projection images (a summation of the intensities along each A-scan) that are presented by the Cirrus HD-OCT instrument (shown in Figure 1). Each of the cubes was rated in a masked fashion by one of the authors with respect to the presence or absence of motion artifacts. Motion artifact was defined as a visible break in any of the major blood vessels in the image exceeding half the diameter of the vessel.
Results:
Table 1 shows the number of cubes that were judged as having visible motion for both the tracked and the untracked cases. Tracking produced a significant increase in the cubes with no visible motion. Thirty nine of the forty cubes with tracking (95%) had no visible motion. This can be compared with only nineteen of the forty cubes (48%) that had no visible motion without the use of tracking.
Conclusions:
OCT projection images provide a rapid and reliable technique to evaluate the motion compensation capabilities of a tracking system. Tracking in Cirrus HD-OCT significantly reduces motion artifacts in the acquired data.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)