SWI脑回低信号提示颅内硬脑膜动静脉瘘可逆性静脉淤血

BACKGROUND AND PURPOSE: Gyral hypointensity (GH) on susceptibility-weighted imaging (SWI) has occasionally been observed in intracranial dural arteriovenous fistulas (dAVFs), but its pathophysiology and clinical relevance remain unclear. This study aimed to characterize GH as an indicator of venous congestion and to evaluate its reversibility and clinical implications after treatment.

MATERIALS AND METHODS: We retrospectively reviewed 48 patients with intracranial dAVFs who underwent successful endovascular treatment and had both pre- and post-treatment SWI available. GH was classified as band-like, brush-like, or mixed based on morphology. Imaging findings, angiographic characteristics, and clinical data were compared between patients with and without GH. Subgroup analyses were performed in retrograde leptomeningeal venous drainage (RLVD) positive cases to assess venous collateral capacity using angiographic contrast stagnation and DSA perfusion delay.

RESULTS: GH was identified in 16 of 48 patients (33.3%), predominantly in those with high-grade shunts and RLVD (100%, p < 0.001). GH correlated with higher pseudophlebitic pattern (PPP) grades (p < 0.001), FLAIR positivity (p < 0.001), DWI restriction (p = 0.012), and focal neurologic deficits (p < 0.001). Among 14 evaluable lesions, 12 (85.7%) showed interval improvement on follow-up SWI. Brush-like GH frequently resolved completely, whereas band-like GH demonstrated limited reversibility. In RLVD-positive cases, coexistence of contrast stagnation on feeder-territory injection and DSA perfusion delay on normal territory injection was significantly associated with GH (r = 0.40, 95% CI [0.05-0.67], p = 0.028).

CONCLUSION: GH on SWI reflects severe cortical venous congestion and demonstrates varying reversibility after treatment. Its appearance likely results from the combined effects of deoxyhemoglobin accumulation, microcirculatory delay, and flow-related phase changes. Recognition of brush-like GH-especially when accompanied by FLAIR or DWI abnormalities-may facilitate early identification of reversible venous pathology and guide timely management in patients with aggressive intracranial dAVF.