MR digital subtraction angiography of cerebral arteriovenous malformations

BACKGROUND AND PURPOSE: Although phase-contrast MR angiography provides som e information regarding hemodynamics of cerebral arteriovenous malformation s (AVMs), most conventional MR angiographic techniques have not been helpfu l in this respect. We attempted to determine the value of MR digital subtra ction angiography (DSA) in assessing AVM hemodynamics. METHODS: We developed an MR DSA technique by combining rapid thick-section T1-weighted imaging with a bolus injection of contrast material. The tempor al resolution was 0.56 to 0.61 seconds per scan. MR DSA images obtained fro m 14 patients with AVMs were reviewed. Anatomic depiction of each component of the AVM was rated using a four-point grading scale (excellent = 3, good 2, fair = 1, poor 0) to compare conventional vs MR angiograms. RESULTS: We were able to obtain serial images in which passage of contrast material was evident within the AVM, although the sequence we used allowed images to be obtained in only one projection. The average score for feeders , nidi, and drainers was 1.6, 2.4, and 2.3, respectively, with an overall a verage of 2.1, CONCLUSION: The spatial resolution of our technique may fall below the leve l needed for identification of small vascular components of an AVM, Additio nally, the limited slab may restrict application of the technique to assess ment of large or very small AVMs, MR DSA, however, can show the hemodynamic s of AVMs and may serve as a supplement to conventional MR imaging in the d iagnosis of cerebral AVMs.