Evaluation of the efferent vein structure of brain arteriovenous malformations using multiplanar reformation in arbitrary planes of the volume-rendered image of three-dimensional rotational angiography.

Systematic studies on the venographic assessment of the draining veins of brain arteriovenous malformations (bAVMs) are lacking. Therefore, in this study, we described the patterns and characteristics of the efferent vein structures using multiplanar reformation in arbitrary planes of the volume-rendering images of three-dimensional rotational angiography. Patients with bAVM who underwent the first session of endovascular therapy in our department between February 2018 and April 2025 were identified. The structure of each efferent vein unit was categorized into simple, unified, bifurcated, or mixed. It was further divided into complex or simple, depending on the presence or absence of the specific intranidal and perinidal venous structure. The venous angioarchitecture of bAVM was analyzed using univariate and multivariate logistic regression analyses. This study included 88 patients (89 lesions). There were 175 efferent veins categorized as single (52 [29.7%]), unified (69 [39.4%]), bifurcated (24 [13.7%]), or mixed (30 [17.1%]). Sixty-nine lesions (77.5%) were classified as having complex venous structures. Multivariate logistic regression analysis showed that a nidus size > 3 cm (p = 0.04, odds ratio [OR]: 6.02, 95% confidence interval [CI]: 1.11-32.70) was associated with the presence of a complex venous structure. We evaluated and categorized the morphological characteristics of the efferent veins of bAVMs. Most patients had complex venous structures. Therefore, using three-dimensional volume-rendering multiplanar reformation in arbitrary planes to assess the bAVMs, particularly those with a nidus size > 3 cm, may benefit preoperative evaluation by understanding the vascular anatomy and flow dynamics.