Cervical Positional Changes Alter Supra-Aortic Branching Geometry: Implications for Transradial Neurointervention.

BACKGROUND: The transradial approach has gained popularity in neurointerventions because of its lower risk of access-site complications. However, catheterization of supra-aortic vessels can be technically challenging, particularly in patients with an unfavorable branching geometry. Although cervical positional changes are sometimes used to facilitate catheter navigation, their quantitative effects on vascular geometry remain unclear. This study aimed to quantitatively evaluate the effects of cervical positional changes on supra-aortic branching angles using three-dimensional time-of-flight magnetic resonance angiography. METHODS: This prospective observational study included patients who underwent cervical magnetic resonance angiography in five predefined positions: neutral, right and left rotation, flexion, and extension. Supra-aortic branching angles including the brachiocephalic artery, left common carotid artery (CCA), and left subclavian artery (SCA), as well as the bifurcation angle between the right SCA-CCA were measured. Positional changes were analyzed using a linear mixed-effects model. RESULTS: Seventy-seven patients were included. The right SCA-CCA bifurcation angle increased during right rotation and extension and decreased during left rotation and flexion. In contrast, the brachiocephalic artery, left CCA, and left SCA demonstrated relatively small angular changes. Pairwise comparisons revealed significant positional differences primarily in the right SCA-CCA segment, whereas no significant differences were observed in the proximal branches after correcting for multiple comparisons. CONCLUSIONS: Cervical positional changes influence supra-aortic branching geometry, particularly at the right SCA-CCA bifurcation. These findings suggest that simple positional adjustments may facilitate catheter navigation during the right transradial approach and may serve as a practical strategy for optimizing vascular access.