© American Roentgen Ray Society MR Imaging of Cerebral

Fifteen vascular malformations, including six supratentorial arteriovenous malforma-tions (AVMs), three venous malformations, and six brainstem vascular malformations, were examined on 0.5 T magnetic resonance (MR) and GE 9800 and 8800 computed tomographic (CT) scanners. All the malformations were shown by MR, and the arterial and venous drainage of AVMs was precisely delineated. Hematoma was always differ-entiated from calcification by MR signal characteristics. Increased signal in the brain parenchyma was often seen adjacent to A VMs. The signal of blood within venous malformations altered with spin-echo techniques using various repetition times and was distinguished from rapidly flowing blood in AVMs that lacked signal in all imaging sequences. Brainstem malformations were seldom demonstrated by angiography. Hem-orrhage was common and was invariably associated with multiple areas of absent signal that may have represented abnormal vessels. These appearances are distinct from those of intrinsic tumors and are probably pathognomonic of brainstem vascular malfor-mations. Vascular malformations present clinically with a variety of symptoms that includ