Correction of motion artifacts and scanning beam distortions in 3D ophthalmic optical coherence tomography imaging

摘要

The ability to obtain true three-dimensional (3D) morphology of the retinal structures is essential for future clinical and experimental studies. It becomes especially critical if the measurements acquired with different instruments need to be compared, or precise volumetric data are needed for monitoring and treatment of retinal disease. On the other hand, it is well understood that optical coherence tomography (OCT) images are distorted by several factors. Only limited work has been performed to eliminate these problems in ophthalmic retinal imaging, perhaps because they are less evident in the more common 2D representation mode of time-domain OCT. With recent progress in imaging speed of Fourier domain -OCT (Fd-OCT) techniques, however, 3D OCT imaging is more frequently being used, thereby exposing problems that have been ignored previously. In this paper we propose possible solutions to minimize and compensate for artifacts caused by subject eye and head motion, and distortions caused by the geometry of the scanning optics. The first is corrected by cross-correlation based B-scan registration techniques; the second is corrected by incorporating the geometry of the scanning beam into custom volume rendering software. Retinal volumes of optical nerve head (ONH) and foveal regions of healthy volunteer, with and without corrections, are presented. Finally, some common factors that may lead to increased distortions of the ophthalmic OCT image such as refractive error or position of the subject's head are discussed.