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Abstract #10478 Published in IGR 6-1
Tracking the optic nervehead in OCT video using dual eigenspaces and an adaptive vascular distribution model
Koozekanani D; Boyer KL; Roberts CIEEE Transactions on Medical Imaging 2003; 22: 1519-1536
Optical coherence tomography (OCT) is a new ophthalmic imaging modality generating cross sectional views of the retina. OCT systems are essentially Michelson interferometers that form images in 1.5 seconds by directing a superluminescent diode (SLD) beam over the retinal surface. Involuntary eye motions frequently cause incorrect locations to be imaged. This motion may leave no obvious artifacts in the scan data and can easily go undetected. For glaucoma monitoring especially, knowing the measurement path, typically a circle concentric with the nerve head, is crucial. The commercially available OCT system displays a near-infrared video of the retina showing the SLD beam. This paper presents a prototype system to detect the nerve head and SLD beam in the video, and report the true scan path relative to the nerve head. Low image contrast and limited resolution make the reliable detection of retinal features difficult. In an adaptive model construction phase, the system directly detects retinal vasculature and the nerve head and incrementally builds a model of the current subject's vascular pattern relative to the optic disk. The nerve head identification is multitiered, using a novel dual eigenspace technique and a geometric comparison of detected vessel positions and nerve head hypotheses. In its operational phase, a correspondence is achieved between the currently detected vasculature and the model. Using subjects not included in training, the system located the optic nerve head to within 5 pixels (0.07 optic disc diameters, an error well below clinical significance) in 99.75% of 2800 video fields. In current clinical practice, motions as large as one to two disc diameters may go undetected, so this is a vast improvement.
Dr. D. Koozekanani, Biomedical Engineering Program, Signal Analysis and Machine Perception Laboratory, Department of Electrical Engineering, College of Medicine, The Ohio State University, Columbus, OH 43210-1272, USA
Classification:
2.14 Optic disc (Part of: 2 Anatomical structures in glaucoma)
6.9.2 Optical coherence tomography (Part of: 6 Clinical examination methods > 6.9 Computerized image analysis)
