MR Imaging of Spinal Arteriovenous Malformations and Fistulas before and after Embolization

Abstract

We evaluated MR myelography (MRM) and MR angiography (MRA) in addition to MRI before and after embolization of spinal arteriovenous malformations (AVMs) and fistulas (AVFs). Thirteen patients underwent MRI before and after embolization. Among these, MRM was performed in 7 cases and MRA in 8. MRM was performed with 2D-fast SE sequences and MRA with 3D-PC sequences following injection of Gd-DTPA. In all intramedullary AVMs, nidus, dilated draining veins and hemorrhage were visualized on MRI MRM and MRA were thought to be useful, but they were not essential for making the diagnosis. In perimedullary and dural AVFs, dilated draining veins and T2-prolonged areas in the cord were visualized, but the fistula itself could not be detected by MRM or MRA. MRM was very sensitive in detecting dilated draining veins around the spinal cord. After embolization, cord enhancement was observed for a relatively long period in patients having dural AVFs with poor clinical results. Closure of the fistula was suggested by marked vascular enhancement presumably due to stagnant flow following feeding vessel occlusion. It could also be verified by disappearance of draining veins on MRA. Verification of fistula closure was difficult using MRM since dilated veins did not rapidly decrease in size and mild dilatation persisted for a long period. MRM and MRA were effective in detecting recurrence. MRM and MRA in addition to MRI are useful in the diagnosis and follow-up of spinal AVMs and AVFs before and after embolization.