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=(V max −V min )/V mean ) and arterial distensibility defined as area pulsatility index (A max −A min )/A mean ) 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 <0.001 for averaged right+left ICA) and decreased between C3 and C7 (0.93±0.13 versus 0.84±0.13, P <0.001) with overall no effect (C1–C7). Conversely, the area pulsatility index decreased between C1 and C3 (0.18±0.06 versus 0.14±0.04, P <0.001) and increased between C3 and C7 (0.14±0.04 versus 0.31±0.09, P <0.001). vPI in men is higher than in women and increases with age ( P <0.015). vPI over the carotid siphon declined with age but remained stable over the whole ICA trajectory. Conclusions Along the whole ICA trajectory, vPI increased from extracranial C1 up to the carotid siphon C3 with overall no effect on vPI between extracranial C1 and intracranial C7 segments. This suggests that the bony carotid canal locally limits the arterial distensibility of the ICA, increasing the vPI at C3 which is consequently decreased again over the carotid siphon. In addition, vPI in men is higher and increases with age.

Background: Increased cerebral blood-flow pulsatility is associated with cerebral small vessel disease (cSVD). Reduced pulsatility attenuation over the internal carotid artery (ICA) could be a contributing factor to the development of cSVD and could be associated with intracranial ICA calcification (iICAC). Purpose: To compare pulsatility, pulsatility attenuation, and distensibility along the ICA between patients with cSVD and controls and to assess the association between iICAC and pulsatility and distensibility. Study Type: Retrospective, explorative cross-sectional study. Subjects: A total of 17 patients with cSVD, manifested as lacunar infarcts or deep intracerebral hemorrhage, and 17 ageand sex-matched controls. Field Strength/Sequence: Three-dimensional (3D) T1-weighted gradient echo imaging and 4D phase-contrast (PC) MRI with a 3D time-resolved velocity encoded gradient echo sequence at 7 T. Assessment: Blood-flow velocity pulsatility index (vPI) and arterial distensibility were calculated for seven ICA segments (C1-C7). iICAC presence and volume were determined from available brain CT scans (acquired as part of standard clinical care) in patients with cSVD. Statistical Tests: Independent t-tests and linear mixed models. The threshold for statistically significance was P < 0.05 (two tailed). Results: The cSVD group showed significantly higher ICA vPI and significantly lower distensibility compared to controls. Controls showed significant attenuation of vPI over the carotid siphon (À4.9% AE 3.6%). In contrast, patients with cSVD showed no attenuation, but a significant increase of vPI (+6.5% AE 3.1%). iICAC presence and volume correlated positively with vPI (r = 0.578) in patients with cSVD and negatively with distensibility (r = À0.386). Conclusion: Decreased distensibility and reduced pulsatility attenuation are associated with increased iICAC and may contribute to cSVD. Confirmation in a larger prospective study is required.

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Background and objectives:Screening for unruptured intracranial aneurysms (UIAs) is effective for first degree relatives (FDRs) of aneurysmal subarachnoid hemorrhage (aSAH) patients. Whether screening is also effective for FDRs of UIA patients is unknown. We determined the yield of screening in such FDRs, assessed rupture risk and treatment decisions of aneurysms that were found, identified potential high-risk subgroups and studied effects of screening on quality of life (QoL).Methods:In this prospective cohort study we included FDRs, aged 20–70 years, of UIA patients without a family history of aSAH who visited the Neurology outpatient clinic in one of three participating tertiary referral centers in the Netherlands. FDRs were screened for UIA with magnetic resonance angiography (MRA) between 2017 and 2021. We determined UIA prevalence and developed a prediction model for UIA risk at screening using multivariable logistic regression. QoL was evaluated with questionnaires six times during the first year following screening and assessed with a linear mixed effects model.Results:We detected 24 UIAs in 23 of 461 screened FDRs, resulting in a 5.0% prevalence (95% CI: 3.2–7.4%). Median aneurysm size was 3mm (IQR: 2–4mm) and median 5-year rupture risk assessed with the PHASES score was 0.7% (IQR: 0.4–0.9%). All UIAs received follow-up imaging, none were treated preventively. After a median follow-up of 24 months (IQR: 13–38 months) no UIA had changed. Predicted UIA risk at screening ranged between 2.3–14.7% with the highest risk in FDRs who smoke and have excessive alcohol consumption (c-statistic: 0.76; 95% CI: 0.65–0.88). At all survey moments health-related QoL (HRQoL) and emotional functioning were comparable with those in a reference group from the general population. One FDR with a positive screen expressed regret about screening.Discussion:Based on the current data, we do not advise screening FDRs of UIA patients, since all identified UIAs had a low rupture risk. We observed no negative effect of screening on QoL. Longer follow-up should determine the risk of aneurysm growth requiring preventive treatment.