Time-resolved Spinal MR Angiography: Initial Clinical Experience in the Evaluation of Spinal Arteriovenous Shunts

Background And Purpose: Spinal arteriovenous shunts usually require digital subtraction angiography (DSA) for evaluation. We report a unique time-resolved spinal MR angiographic (TRSMRA) technique with a temporal resolution of 3-6 seconds and spatial resolution of approximately 1 mm(3) that has the potential to noninvasively detect, localize, and follow-up these cases.

Materials And Methods: Eleven patients with clinical presentation and/or MR findings suspicious for a spinal arteriovenous shunt were referred for TRSMRA. Patients subsequently underwent spinal DSA to confirm the presence or absence of a shunt or were followed clinically until an alternative diagnosis was found. TRSMRA was also used to predict the level of the shunt in the positive cases. In addition, 2 of these patients as well as a 12th patient referred to us posttreatment received a follow-up TRSMRA to assess treatment outcome.

Results: Early venous shunting was identified by using TRSMRA in 6 cases. All 6 were confirmed to have an AV shunt on subsequent spinal DSA. The shunt level predicted by TRSMRA consistently correlated with DSA to within 1 vertebral level. In the 5 patients with a negative screening TRSMRA, DSA or clinical outcome confirmed the absence of an arteriovenous shunt in all of the cases. Posttreatment TRSMRA in 3 patients accurately assessed the success or failure of treatment.

Conclusion: Combining acceleration techniques to achieve high frame rate TRSMRA provides sufficient temporal and spatial resolution to identify, localize, and follow patients suspected of having a spinal arteriovenous shunt. Further study in a larger population is warranted to assess the accuracy of this technique.