MRI follow-up of embolized intracranial dural arteriovenous fistulas using 3D time-of-flight and contrast-enhanced 3D T1-weighted GRE imaging.

BACKGROUND: Although digital subtraction angiography (DSA) remains the reference standard for post-treatment follow-up of intracranial dural arteriovenous fistulas (DAVFs), it is an invasive procedure associated with procedural risks and may not be justified for the follow-up of all DAVFs. PURPOSE: This study aimed to evaluate the diagnostic performance of 3D time-of-flight (3D TOF) and contrast-enhanced 3D T1-weighted gradient-echo (3D T1 Gd) magnetic resonance imaging (MRI) sequences for monitoring embolized intracranial DAVFs. MATERIALS AND METHODS: In this retrospective single-center study, consecutive patients with embolized DAVFs between 2004 and 2023, who underwent MRI and arteriography during follow-up, were evaluated. 3D TOF sequence images were independently reviewed by two readers to assess treatment completeness. In cases of residual fistula, cortical venous drainage (CVD) was evaluated. Patency of the fistulous or proximal venous sinus was assessed on contrast-enhanced 3D T1-weighted GRE imaging. The median follow-up duration was 3.6 months (interquartile range [IQR], 3.0-8.4 months). Imaging findings were systematically compared with DSA as the reference standard. RESULTS: Seventy-six patients (mean age, 56 ± 12,8 years; 46 men) with 78 embolized DAVFs were included. The positive predictive value, negative predictive value, and diagnostic accuracy of 3D TOF sequence for the detection of residual fistulas were 79% [54% - 94%], 93% [84% - 98%], 90% [81% - 95%], respectively. Inter-rater agreement was good (κ = 0.71; [0.52-0.90]). Intermodality agreement was good for the detection of residual fistulas (κ = 0.72; [0.54-0.90]) and moderate for the detection of cortical venous drainage (κ = 0.54; [0.22-0.85]). Additionally, agreement between 3D T1 Gd and DSA for assessing venous sinus patency was good (κ = 0.80; [0.58-1.00]). CONCLUSION: 3D TOF and contrast-enhanced 3D T1-weighted GRE imaging are effective non-invasive tools for the follow-up of embolized DAVFs. 3D TOF provides high diagnostic performance for excluding clinically significant residual fistulas, whereas small residual microshunts or low-flow fistulas may remain occult and still require DSA confirmation in selected cases.