Intraocular hemorrhage and mimicking lesions: role of gradient-echo and contrast-enhanced MRI.

Intraocular hemorrhage and mimicking lesions on precontrast spin-echo magnetic resonance images were examined with contrast material and/or gradient-echo pulse sequence. Twenty-two melanomas, nine retinoblastomas, four hemorrhages, one metastasis, and one toxocara endophthalmitis were examined. With contrast material, all tumors demonstrated enhancement, whereas hemorrhage did not. Retinoblastomas demonstrated a heterogeneous enhancement pattern. Computed tomography demonstrated corresponding intratumoral calcifications at the areas of no enhancement. Gradient-echo images demonstrated a heterogeneous pattern in the majority of the lesions compared to spin-echo images. However, relatively characteristic small round areas of signal drop-off representing calcification were observed in about half of the retinoblastomas.