MR digital subtraction angiography of cerebral arteriovenous malformations

Abstract

Background and purpose: Although phase-contrast MR angiography provides some information regarding hemodynamics of cerebral arteriovenous malformations (AVMs), most conventional MR angiographic techniques have not been helpful in this respect. We attempted to determine the value of MR digital subtraction 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 temporal resolution was 0.56 to 0.61 seconds per scan. MR DSA images obtained from 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 average of 2.1.

Conclusion: The spatial resolution of our technique may fall below the level needed for identification of small vascular components of an AVM. Additionally, the limited slab may restrict application of the technique to assessment of large or very small AVMs. MR DSA, however, can show the hemodynamics of AVMs and may serve as a supplement to conventional MR imaging in the diagnosis of cerebral AVMs.

fig 1.

48-year-old woman with left frontal AVM. A and B, Conventional angiograms show an AVM fed by branches of the anterior cerebral artery. It drains into the superior sagittal sinus via several draining veins. C–G, Original images of MR DSA (5/2.3/1) in the sagittal plane. C is a mask image. Scans for D, E, F, and G were initiated 1.22 seconds, 2.44 seconds, 4.27 seconds, and 7.93 seconds after C, respectively. Scanning time for each image was 0.61 seconds.(cont'd) →

fig 1.

← (cont'd) H–K, Gray-scale–reversed MR DSA images of H, I, J, and K correspond to source images of D, E, F, and G, respectively. Demonstration of each component of the AVM was graded as excellent (feeder = 3, nidus = 3, drainer = 3). Note the carotid siphon remains visible when major veins and dural sinuses are shown (K)

fig 2.

24-year-old woman with cerebellar vermian AVM. A, Conventional angiogram shows a nidus of an AVM fed by the superior cerebellar artery draining to the vein of Galen. B and C, MR DSA images (5/2.3/1) in the sagittal plane clearly show each component of the AVM (feeder = 3, nidus = 3, drainer = 3).

fig 3.

66-year-old woman with right parietal AVM. A and B, Conventional angiograms show an AVM fed by the angular artery draining into the superior sagittal sinus via an enlarged cortical vein. C–E, MR DSA images (5/2.3/1) in the sagittal plane clearly show the nidus and drainer. Part of the feeder just proximal to the nidus is not visible because it is outside the scanned section (feeder = 2, nidus = 3, drainer = 3).