Abstract
The 3-D spectral-domain optical coherence tomography (SD-OCT) images of the retina often do not reflect the true shape of the retina and are distorted differently along the x and y axes. In this paper, we propose a novel technique that uses thin-plate splines in two stages to estimate and correct the distinct axial artifacts in SD-OCT images. The method was quantitatively validated using nine pairs of OCT scans obtained with orthogonal fast-scanning axes, where a segmented surface was compared after both datasets had been corrected. The mean unsigned difference computed between the locations of this artifact-corrected surface after the single-spline and dual-spline correction was 23.36 ± 4.04 μm and 5.94 ± 1.09 μm, respectively, and showed a significant difference (p < 0.001 from two-tailed paired t-test). The method was also validated using depth maps constructed from stereo fundus photographs of the optic nerve head, which were compared to the flattened top surface from the OCT datasets. Significant differences (p < 0.001) were noted between the artifact-corrected datasets and the original datasets, where the mean unsigned differences computed over 30 optic-nerve-head-centered scans (in normalized units) were 0.134 ± 0.035 and 0.302 ± 0.134, respectively.
Highlights
Optical coherence tomography (OCT) is a non-invasive imaging modality and is widely used in the diagnosis and management of ocular diseases
Nine pairs of macula-centered OCT scans were obtained on a SD-OCT1000 spectral-domain scanner (Topcon Corp., Tokyo, Japan) from 9 normal subjects participating in the Rotterdam Study, which is a prospective population-based cohort study investigating age-related disorders
Eliminating motion artifacts in OCT images is important as it brings the dataset into a consistent shape and makes visualization and subsequent analysis easier
Summary
Optical coherence tomography (OCT) is a non-invasive imaging modality and is widely used in the diagnosis and management of ocular diseases. The new spectral-domain optical coherence tomography (SD-OCT) [1, 2] scanners show a higher signal-to-noise ratio than the Received 20 Jun 2011; revised 13 Jul 2011; accepted 19 Jul 2011; published 27 Jul 2011 1 August 2011 / Vol 2, No 8 / BIOMEDICAL OPTICS EXPRESS 2404 previous generation time-domain OCT scanners, and provide close-to-isotropic volumetric images (see Fig. 1(a)) of the retina These images often show large artifactual shifts of the individual A-scans, which are thought to be the result of a number of factors, including motion of the eye and positioning of the camera. (c) A typical central B f -scan (xz-slice) from an unprocessed ONH-centered volume, showing the tilt artifact commonly seen in these slices. The need to correct these artifacts and bring the dataset into a more consistent, predictable shape is compelling
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