T1 Hyperintense Lesions

CASE A: An oval, nonenhancing, T1 hyperintense right parietal abnormality is evident. Associated T2 hyperintensity and peripheral susceptibility are seen. There also is surrounding edema. The findings are consistent with a late subacute hemorrhage in a patient with a known history of amyloid angiopathy.

CASE B: A mass centered within the right cerebral peduncle demonstrates T1 hyperintense foci and heterogeneous T2 hyperintense signal with surrounding edema. The postcontrast T1-weighted image demonstrates an avidly enhancing mass consistent with a pathologically proven hemorrhagic renal cell carcinoma metastasis.

CASE C: A large heterogeneous mass with regions of T1 hyperintensity and an associated sinus tract is centered within the midline inferior posterior fossa. No enhancement is identified. There are fat-fluid levels in the frontal horns of the lateral ventricles with chemical shift artifact on the T2-weighted images as well as multiple small T1 hyperintense foci consistent with fat within the bilateral sylvian fissures. These findings are consistent with a ruptured dermoid cyst.

CASE D: A large, oval, well-circumscribed, T1 hyperintense, T2 hypointense, nonenhancing intraventricular mass is noted in the region of the foramen of Monro. The location and imaging characteristics of this lesion are consistent with a proteinaceous colloid cyst.

CASE E: There are bilateral medial temporal and right thalamic intraparenchymal as well as scattered leptomeningeal T1 hyperntense lesions. No associated enhancement is identified. These findings are consistent with melanocytic deposits in a patient with neurocutaneous melanosis.