[Magnetic resonance imaging in the evaluation of malignant melanoma of the choroid and ciliary body].

We evaluated 16 patients with malignant melanomas of the choroid (11) or the ciliary body (5) by magnetic resonance imaging (MRI), using a 0.5 T magnet and a surface coil. The tumor was seen in all cases, hyperintense in T1-weighted images, and hypointense in T2-weighted sequences (80%). These images reflected the short T1 and T2 relaxation times caused by the presence of melanin in those tumors. This non-invasive method was superior to computed tomography (70%), and sometimes superior to fundoscopy (2 cases), angiofluorography (3 cases) or echography (1 case). MRI also proved valuable for differentiating uveal melanoma from associated subretinal effusion.