Hemodynamic Parameters in the Parent Arteries of Unruptured Intracranial Aneurysms Depend on Aneurysm Size and Are Different Compared to Contralateral Arteries: A 7 Tesla 4D Flow MRI Study

Background Different Circle of Willis (CoW) variants have variable prevalences of aneurysm development, but the hemodynamic variation along the CoW and its relation to presence and size of unruptured intracranial aneurysms (UIAs) are not well known. Purpose Gain insight into hemodynamic imaging markers of the CoW for UIA development by comparing these outcomes to the corresponding contralateral artery without an UIA using 4D flow magnetic resonance imaging (MRI). Study Type Retrospective, cross‐sectional study. Subjects Thirty‐eight patients with an UIA, whereby 27 were women and a mean age of 62 years old. Field Strength/Sequence Four‐dimensional phase‐contrast (PC) MRI with a 3D time‐resolved velocity encoded gradient echo sequence at 7 T. Assessment Hemodynamic parameters (blood flow, velocity pulsatility index [vPI], mean velocity, distensibility, and wall shear stress [peak systolic (WSSMAX), and time‐averaged (WSSMEAN)]) in the parent artery of the UIA were compared to the corresponding contralateral artery without an UIA and were related to UIA size. Statistical Tests Paired t‐tests and Pearson Correlation tests. The threshold for statistical significance was P