Patterns of indocyanine green videoangiography of choroidal tumours

Indocyanine green video-angiography is a recently popularised technique for imaging the retina and choroid. Little is known about the value of this technique in the evaluation of choroidal tumours.

Indocyanine green video-angiograms of 51 patients with choroidal tumours, including 32 with choroidal melanoma, five with choroidal naevus, four with choroidal metastasis, four with choroidal haemangioma, one with choroidal osteoma, one with choroidal vortex vein varix, and four with irradiated choroidal melanoma were reviewed in a masked fashion.

The choroidal melanoma group achieved maximal fluorescence at an average of 18.2 (range 0.4 to 60) minutes after injection. At maximum fluorescence, the pattern varied from hypofluorescent in 17 cases, to isofluorescent in eight cases, and hyperfluorescent in seven cases. Non-pigmented choroidal melanoma generally showed an earlier average onset of fluorescence than the pigmented choroidal melanoma (mean 28 versus 185 seconds, respectively) (p = 0.04). The two subgroups otherwise overlapped substantially in angiography characteristics. The choroidal metastasis group demonstrated maximal fluorescence at an average of 8.9 (range 1.7 to 13) minutes. All choroidal metastases had a homogeneous diffuse fluorescence with late isofluorescence. The choroidal metastases allowed a subtle blurred perception of the normal choroidal pattern through the tumour. The choroidal haemangioma group revealed very characteristic findings with an onset of filigree fluorescence at an average of 0.6 (range 0.4 to 0.7) minutes with little variation. The maximal fluorescence was typically hyperintense in all cases and was achieved at an average of 1.2 minutes and was reached by 1.8 minutes in all cases. In these cases the fluorescence appeared as a lacy diffuse 'fluorescent mulberry' pattern with visibility of the vascular channels and demonstrated 'washout' of the dye in the late frames.

Indocyanine green may be a useful adjunct in the differentiation of amelanotic choroidal melanoma, choroidal metastasis, and choroidal haemangioma. The different patterns of fluorescence may be explained by the intrinsic choroidal vascular architecture in these three tumours.