Multimodal Registration Procedure for the Initial Spatial Alignment of a Retinal Video Sequence to a Retinal Composite Image

Abstract

Abstract-Accurate placement of lesions is crucial for the effectiveness and safety of a retinal laser photocoagulation treatment. Computer assistance provides the capability for improvements to treatment accuracy and execution time. The idea is to use video frames acquired from a scanning digital ophthalmoscope (SDO) to compensate for retinal motion during laser treatment. This paper presents a method for the multimodal registration of the initial frame from an SDO retinal video sequence to a retinal composite image, which may contain a treatment plan. The retinal registration procedure comprises the following steps: 1) detection of vessel centerline points and identification of the optic disc; 2) prealignment of the video frame and the composite image based on optic disc parameters; and 3) iterative matching of the detected vessel centerline points in expanding matching regions. This registration algorithm was designed for the initialization of a real-time registration procedure that registers the subsequent video frames to the composite image. The algorithm demonstrated its capability to register various pairs of SDO video frames and composite images acquired from patients.Index Terms-Biomedical image processing, feature extraction, retinal image registration, retinal video sequences.

Real-Time Multimodal Retinal Image Registration for a Computer-Assisted Laser Photocoagulation System

“…Our registration procedure assumes that the composite image was segmented and the initial frame from the retinal video sequence was registered to the composite image using our initial alignment method presented in [18]. The spatial relationship between the initial video frame and the reference image is described through a nonlinear quadratic (second-order polynomial) transformation.…”