Computer-assisted quantitation of choroidal neovascularization for clinical trials

PURPOSE. To develop a computer-assisted method for the quantitation of chor oidal neovascularization (CNV) for the support of clinical trials. METHODS. Fluorescein angiographic images were selected from 5 patients enro lled in a clinical trial for which three follow-up visits were available. T hirty- and 600-second images were digitized at 1000 dots/in and registered (aligned) with polynomial warping algorithms. Custom-developed software all owed for coarse, automated identification of CNV. An easy-to-use graphical user interface facilitated supervision and refinement of the lesion boundar ies by a skilled reader based on standard stereoscopic viewing of the fluor escein angiography study. Capabilities for boundary delineation in both ear ly and late phases, and animation to allow for image correlation and evalua tion 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 superv ision. Second, an integrated lesion intensity (ILI) reflecting the integrat ed, normalized lesion hyperfluorescence was calculated. RESULTS. Area and ILI measures were calculated for each of 5 patients for t hree or more visits. Facile supervision based on the stereoscopic angiogram permitted arbitrarily close concordance with CNV identification using stan dard methods. Changes in area and ILI measurements between visits correlate d closely with clinically observed changes in each case. CONCLUSIONS. Interactive image processing permits efficient, accurate, comp uter-assisted CNV quantitation that may be useful for the support of clinic al trials and preclinical studies.