NMR imaging of congenital intracranial germinal layer neoplasms.

NMR images in five patients with surgically proved, congenital germinal layer intracranial neoplasms (two dermoid and three epidermoid tumors) were reviewed. The dermoids were typically midline (suprasellar or parapineal) masses with sharply-defined margins. Relaxation times were variable, but if fat was present, T1 was decreased, and T2 was increased. The epidermoids were off the midline (cerebellopontine angle, temporal lobe, frontal lobe) masses with generally long T1 and T2 relaxation times. Obstructive hydrocephaly was noted in one patient, and tumor to ventricular communication was demonstrated in another.