Indocyanine green angiography: an evaluation of image enhancement for the identification of occult choroidal neovascular membranes.

Abstract

To determine the diagnostic yield of occult choroidal neovascularization from examination of nonenhanced digital indocyanine green (ICG) angiograms versus examination of both nonenhanced and contrast-enhanced angiograms. Fifty consecutive occult choroidal neovascular membranes were examined using ICG angiography at the Queen's University Eye Department. These studies were retrospectively reviewed in a masked fashion using the nonenhanced images. A subsequent examination of the same images was then performed using both the nonenhanced and contrast-enhanced images. Each study was graded as focal hyperfluorescence, plaque hyperfluorescence, isofluorescence, or hypofluorescence. Of the cases reviewed, only 36% (18/50) of the membranes were well-defined on nonenhanced ICG angiography, compared with 58% (28/50) using image enhancement in addition to the nonenhanced images. This was a statistically significant difference in image definition between the two groups (chi-square test; P < 0.005). Contrast-enhanced angiograms, when used in conjunction with nonenhanced ICG images, allowed for a significantly higher diagnostic yield when compared with the study of nonenhanced images alone.