Multimodal MRI features of spinal perimedullary versus dural arteriovenous fistulas: an exploratory analysis

Differentiation between spinal dural arteriovenous fistula (SDAVF) and perimedullary arteriovenous fistula (SPAVF) is crucial for treatment planning, but reliable non-invasive modalities remain limited. This study aimed to identify discriminative multimodal MRI features for differentiating SPAVF from SDAVF.

This retrospective study enrolled 34 patients (13 SPAVF, 21 SDAVF) confirmed by digital subtraction angiography (DSA) between January 2016 and December 2025. All patients underwent conventional T2-weighted imaging (T2WI), T2-weighted sampling perfection with application-optimized contrasts using different flip-angle evolutions (T2W-SPACE), and contrast-enhanced magnetic resonance angiography (CE-MRA). Two neuroradiologists independently evaluated multimodal imaging characteristics. Diagnostic performance was assessed using receiver operating characteristic (ROC) curve analysis with bootstrap resampling.

SPAVF predominantly demonstrated anterior/posterior spinal artery supply (84.61% vs. 0%, P < 0.001), multiple feeding arteries (61.54% vs. 4.76%, P < 0.001), and caudal venous drainage (53.85% vs. 9.52%, P = 0.004) compared with SDAVF. On T2W-SPACE, SPAVF exhibited significantly larger maximum PFV caliber (5.04 mm vs. 1.74 mm, P < 0.001), partial flow void signal (76.92% vs. 0%, P < 0.001), and pial surface fistula location (100% vs. 0%, P < 0.001). CE-MRA revealed larger fistula caliber in SPAVF (5.22 mm vs. 3.21 mm, P < 0.001). ROC analysis demonstrated excellent discriminatory power for SPACE maximum PFV caliber (AUC, 0.96; 95% CI 0.85-0.99; P < 0.001) and CE-MRA fistula caliber (AUC, 0.92; 95% CI 0.76-0.98; P < 0.001).

T2W-SPACE and CE-MRA enables accurate non-invasive differentiation of SPAVF from SDAVF. SPACE maximum PFV caliber and CE-MRA fistula caliber serve as robust quantitative biomarkers, providing reliable preoperative guidance and potentially reducing dependence on diagnostic DSA.