Comparison of MRI, CT and angiography in cerebral arteriovenous malformations

Computed tomography (CT), magnetic resonance imaging (MRI) and cerebral angiography were performed in 30 patients with cerebral arteriovenous malformations (AVMs). Clinical data and radiographic findings are presented. The diagnostic values of CT and MRI are compared. 25 of 30 AVMs were seen on CT-scans, 27 on MR-images, 26 by angiography. Typical CT-findings were irregularly hyperdense areas with spotlike contrast enhancement. 4 out of 5 AVMs not depicted by CT were diagnosed for tumor, in one case the malformation was hidden by a hematoma. MRI mostly showed the AVM as round or oval lesions with spongelike structure of low signal intensity in T1-weighted sequences or as single enlarged vessels. The 26 AVM revealed by angiography presented typically enlarged vessels; in 2 cases angiography was without any pathological findings, 2 cases showed signs of a space occupying lesion. The results confirm that MRI is superior to CT in detecting and recognizing AVM. Its strength lies in the possibility to detect abnormal vessels even in presence of fresh or older hematoma, and in the precise information on size and location of the AVM. In our series, MRI and CT-scans together showed 28 of 30 AVMs, the remaining 2 cases were not seen with angiography either but only proven histologically. Although today MR-angiography is able to provide three dimensional images of blood vessels, it cannot yet replace angiography in the exact study of the vessels which is required for surgical planning.