Malignant uveal melanoma and similar lesions studied by computed tomography.

Abstract

Patients (44) with intraocular disease were studied by computed tomography (CT); in 19 cases malignant uveal melanoma was considered the likely diagnosis. CT proved to be accurate in determining the location and size of uveal melanomas, demonstrating scleral invasion and differentiating melanoma from choroidal detachment or angioma, toxocariasis and senile macular degeneration. Astrocytic retinal hamartoma and medulloepithelioma could not be distinguished from melanoma with CT. On CT, uveal melanomas appeared as hyperdense lesions with slight to moderate contrast enhancement. Tumors < 2 mm could not be seen. Using dynamic CT, moderate peak amplitude, normal or delayed tissue transit time, and persistently elevated washout phase (downslope) were noted, indicating increased permeability as the result of an impaired tumor blood barrier. Histological types of uveal melanoma could not be differentiated on the basis of circulatory patterns. Dynamic CT may be useful in distinguishing uveal melanoma from choroidal hemangioma or hematoma.