CHOROIDAL HEMANGIOMA - MR FINDINGS AND DIFFERENTIATION FROM UVEAL MELANOMA

BACKGROUND AND PURPOSE: The aim of this study was to establish the MR imaging characteristics of choroidal hemangioma and to compare them wi th those of uveal melanoma, METHODS: Among 41 patients examined at 1.5 T (4-cm surface coil, T1-weighted and fast spin-echo T2-weighted sequ ences), 25 had uveal melanoma and 16 had circumscribed choroidal heman gioma. After IV bolus injection of gadopentetate dimeglumine, dynamic and T1-weighted sequences were acquired. RESULTS: In patients with cho roidal hemangioma, uniform signal characteristics were detected on fas t T2-weighted images. In 15 of 16 patients with choroidal hemangioma, lesions were isointense with vitreous on fast spin-echo T2-weighted im ages, whereas lesions in 24 of 25 patients with uveal melanoma were hy pointense, Signal characteristics of uveal melanoma and hemangioma did not differ significantly on plain T1-weighted images. Enhancement was earlier and much stronger for circumscribed choroidal hemangioma than for uveal melanoma. After TV bolus application of gadopentetate dimeg lumine, the increase of signal intensity was higher for circumscribed choroidal hemangioma (signal intensity ratio, 5.8) than for uveal mela noma (signal intensity ratio, 2.2). CONCLUSION: Circumscribed choroida l hemangioma may be difficult to differentiate from melanoma by ophtha lmologic examination, Differentiation may not be possible if direct vi ewing of uveal space-occupying lesions is hampered by opaque vitreous media, The characteristic findings on fast spin-echo T2-weighted MR im ages and early enhanced images aid in differentiating choroidal hemang ioma from uveal melanoma.