Hemodynamic relationship with angioarchitecture of cerebral arteriovenous malformation and changes after embolization: a pilot study by 4D flow MR.

BACKGROUND

The hemodynamics of cerebral arteriovenous malformation (cAVM) is difficult to evaluate with conventional imaging or clinical grading. The aim of this study is to: (I) investigate the association between the angioarchitecture and hemodynamic parameters in cAVM based on 4-dimentional flow magnetic resonance (4D flow MR); (II) quantify flow changes during follow-up after embolization and explore the potential of flow-guided staged embolization.

METHODS

Twenty-one patients with digital subtraction angiography (DSA)-diagnosed cAVM were prospectively enrolled in a tertiary hospital consecutively from April 2022 to January 2024 for a cohort study. Lesion angioarchitecture at baseline was assessed by DSA. 4D flow MR was performed to assess hemodynamics. Flow-derived parameters included velocity, flow, time averaged wall shear stress (WSS) of the main feeding artery, and inflow-to-outflow ratio. Hemodynamic metrics were compared between groups with different angioarchitecture and rupture status. Seven patients had a post embolization follow-up 4D flow MR scan with a median interval of 8.9 months.

RESULTS

Among multiple angioarchitectural features, supply by a single feeding artery (6/7 in the ruptured group and 0/14 in the unruptured group, P<0.001) and intra nidal aneurysm (7/7 in the ruptured group and 5/14 in the unruptured group, P=0.007) were significantly associated with lesion rupture. The ruptured cAVM showed lower total flow of feeding arteries (2.09±3.15 . 6.05±3.76 mL/s, P=0.029), lower WSS (0.99±0.73 . 2.10±0.45 Pa, P=0.023) and higher inflow-to-outflow ratio (2.46±0.79 . 1.46±0.55, P=0.041). During follow-up, the total flow of the lesions decreased by 10-100% after the embolization. The nidus volume decreased significantly (reduction rate: 59.6-100%, P=0.009). The flow of the minor feeding artery increased in 2 cases out of 5, indicating flow remodeling. Three patients had a second embolization guided by the follow-up imaging.

CONCLUSIONS

cAVM lesions tend to have heterogeneous hemodynamics even with similar angioarchitecture. This could be captured and quantified on an individual basis using 4D flow MR. Flow analysis by MR offers the potential to guide a second embolization.