Computer-assisted quantitation of choroidal neovascularization for clinical trials.

PURPOSE To develop a computer-assisted method for the quantitation of choroidal neovascularization (CNV) for the support of clinical trials. METHODS Fluorescein angiographic images were selected from 5 patients enrolled in a clinical trial for which three follow-up visits were available. Thirty- and 600-second images were digitized at 1000 dots/in and registered (aligned) with polynomial warping algorithms. Custom-developed software allowed for coarse, automated identification of CNV. An easy-to-use graphical user interface facilitated supervision and refinement of the lesion boundaries by a skilled reader based on standard stereoscopic viewing of the fluorescein angiography study. Capabilities for boundary delineation in both early and late phases, and animation to allow for image correlation and evaluation of temporal changes in fluorescence of spatially corresponding pixels, were included. Two metrics for CNV characterization were generated. First, the lesion area based on the lesion boundaries was identified after supervision. Second, an integrated lesion intensity (ILI) reflecting the integrated, normalized lesion hyperfluorescence was calculated. RESULTS Area and ILI measures were calculated for each of 5 patients for three or more visits. Facile supervision based on the stereoscopic angiogram permitted arbitrarily close concordance with CNV identification using standard methods. Changes in area and ILI measurements between visits correlated closely with clinically observed changes in each case. CONCLUSIONS Interactive image processing permits efficient, accurate, computer-assisted CNV quantitation that may be useful for the support of clinical trials and preclinical studies.