Does the Internal Carotid Artery Attenuate Blood-Flow Pulsatility in Small Vessel Disease?: A 7 T 4D-Flow MRI Study

Abstract

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 age- and 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 (−4.9% ± 3.6%). In contrast, patients with cSVD showed no attenuation, but a significant increase of vPI (+6.5% ± 3.1%). iICAC presence and volume correlated positively with vPI (r = 0.578) in patients with cSVD and negatively with distensibility (r = −0.386). 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. Evidence Level: 2. Technical Efficacy: Stage 2.