Clinically documented hemorrhage in cerebral arteriovenous malformations: MR characteristics.

This study assessed the ability of magnetic resonance (MR) imaging to identify vascular characteristics of cerebral arteriovenous malformations (AVMs) which are predictive of hemorrhage. The study also evaluated the sensitivity and specificity of spin-echo (SE) and gradient-recalled-echo (GRE) imaging in the detection of prior clinical hemorrhage on the basis of location of the hemorrhage (parenchymal, intraventricular, or subarachnoid). Fifty patients with high-flow AVMs were evaluated. Twenty-four (48%) patients had prior clinical hemorrhage documented at computed tomography or MR imaging at the time of bleeding. Central venous drainage (P less than .001), central AVM location (P less than .001), and peri- or intraventricular AVM location (P less than .01) correlated positively with prior clinical hemorrhage. Intranidus aneurysms and angiomatous change could not be detected with MR. Nineteen of the 24 patients with prior hemorrhage underwent both SE and GRE imaging. Hypointensity, indicating the presence of iron from prior hemorrhage, was demonstrated in 14 of 19 T2-weighted SE images (sensitivity, 74%) and in 18 of 19 GRE images (sensitivity, 95%). No patient without a prior episode of clinical bleeding demonstrated evidence of iron deposition at MR imaging (specificity, 100%).