MR Imaging of Central Nervous System Tumors that Do Not Display Increase in Tl or T2

Abstract
A retrospective review of brain tumors examined with magnetic resonance imaging has shown that \2% of tumors or their components do not display evidence of an increase in Tl or T2 when examined with highly Tl dependent inversion recovery or highly T2 dependent spin echo sequences. This was observed in lipid containing tumors, malignant melanomas, tumors containing hemorrhage, acoustic neuromas, meningiomas, hamartomas, a pituitary prolactinoma, astrocytomas (grade I) treated with radiotherapy, pediatric tumors, and cases of unknown cause.