The Role of MRA as a Preliminary Diagnostic Tool in Diagnosing and Localizing Spinal Dural Arteriovenous Fistula.

Background and purpose: Despite advances in imaging techniques, spinal dural arteriovenous fistulas (SDAVFs) may be misdiagnosed, leading to delays in treatment and in some cases irreversible neurologic damage. Spinal DSA has been considered the standard in diagnosing SDAVFs; however, it is operator-dependent and often technically difficult, which can result in false-negative results. MRI/MRA has been established as a sensitive and specific imaging technique in diagnosing SDAVF and in identifying the correct level of the fistula. We present our experience with diagnosing SDAVF by using MRI/MRA and propose MRA as a complementary imaging technique to DSA in diagnosing and localizing SDAVF.

Materials and methods: Once institutional review board approval was granted, data were retrospectively collected from records of 30 patients with surgically proved cases of type I SDAVFs at a large tertiary academic center. This search included records from 2010-2024. Eligibility criteria included any patient with a surgically proved SDAVF, or patients treated by embolization for SDAVF in whom preoperative MRI and DSA had been obtained. Of these patients, 15 had preoperative spinal MRA. The demographic variables collected included patient age, sex, prior spine surgery history, symptomatology, and outcomes.

Results: In all 30 patients, an SDAVF was suggested on routine MRI. In 7 cases, DSA was negative. In all 15 patients who had MRA before treatment at our institution, the MRA was positive for SDAVFs. In 3 cases the MRA was done after DSA at our institution failed to identify the SDAVFs and the patient was taken to surgery based on the MRA results alone. In 4 patients with outside institution negative DSAs, MRAs at our institution were positive and subsequently had positive DSA.

Conclusions: Our findings suggest that MRA is a highly sensitive tool for detecting SDAVF and should be used before DSA, to decrease the likelihood of false-negative DSAs. A limited spinal DSA may also be considered in cases in which MRA clearly identifies the fistula level.