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Background Hemodynamic stress is linked to the development of intracranial aneurysms (IAs) and may be influenced by anatomic variation of intracranial arteries. We assessed diameters and bifurcation angles of intracranial arteries forming the circle of Willis in a cohort of individuals screened for the presence of IAs. Methods Individuals with and without IAs identified at screening with magnetic resonance angiography were compared. Diameters and bifurcation angles of the following arteries were measured using semiautomatic methods: A1 and A2 segments of the anterior cerebral artery, M1 and M2 segments of the middle cerebral artery, P1 segments of the posterior cerebral artery, posterior communicating artery (Pcom), internal carotid artery, vertebral artery, and basilar artery. We employed univariate general linear models to assess group differences. This included subgroup comparisons between individuals with IAs at specific locations and matched controls, and comparisons on group level between individuals with and without IAs, corrected for age and sex. Results In 94 of the 1049 individuals (9.0%) included, IAs were detected. Individuals with middle cerebral artery IAs had wider ipsilateral M2–M2 bifurcation angles compared with controls (121±25° versus 97±19°; P

Background Attenuation of velocity pulsatility along the internal carotid artery (ICA) is deemed necessary to protect the microvasculature of the brain. The role of the carotid siphon within the whole ICA trajectory in pulsatility attenuation is still poorly understood. This study aims to assess arterial variances in velocity pulsatility and distensibility over the whole ICA trajectory, including effects of age and sex. Methods and Results We assessed arterial velocity pulsatility and distensibility using flow‐sensitized 2‐dimensional phase‐contrast 3.0 Tesla magnetic resonance imaging in 118 healthy participants. Velocity pulsatility index (vPI=(Vmax−Vmin)/Vmean) and arterial distensibility defined as area pulsatility index (Amax−Amin)/Amean) were calculated at C1, C3, and C7 segments of the ICA. vPI increased between C1 and C3 (0.85±0.13 versus 0.93±0.13, P