4D flow MRI for intracranial hemodynamics assessment in Alzheimer’s disease

Abstract

Cerebral blood flow, arterial pulsation, and vasomotion play important roles in the transport of waste metabolites out of the brain. Impaired vasomotion results in reduced driving force for the perivascular/glymphatic clearance of beta-amyloid. Noninvasive cerebrovascular characteristic features that potentially assess these transport mechanisms are mean blood flow (MBF) and pulsatility index (PI). In this study, 4D flow MRI was used to measure intra-cranial flow features, particularly MBF, PI, resistive index (RI) and cross-sectional area in patients with Alzheimer's disease (AD), mild cognitive impairment and in age matched and younger cognitively healthy controls. Three-hundred fourteen subjects participated in this study. Volumetric, time-resolved phase contrast (PC) MRI data were used to quantify hemodynamic parameters from 11 vessel segments. Anatomical variants of the Circle of Willis were also cataloged. The AD population reported a statistically significant decrease in MBF and cross-sectional area, and also an increase in PI and RI compared to age matched cognitively healthy control subjects. The 4D flow MRI technique used in this study provides quantitative measurements of intracranial vessel geometry and the velocity of flow. Cerebrovascular characteristics features of vascular health such as pulsatility index can be extracted from the 4D flow MRI data.

Four-dimensional MRI flow examinations in cerebral and extracerebral vessels – ready for clinical routine?

“…Radial and spiral sampling strategies have advantages over standard Cartesian sampling schemes in obtaining larger spatial coverage via undersampling methods. In fact, total scan time for a 4D flow MRI study covering the entire intracranial vasculature was reported between 4–8 minutes using a highly optimized radial 4D flow sequence (3D PC-VIPR) (76, 96, 97). …”

Standardized Evaluation of Cerebral Arteriovenous Malformations Using Flow Distribution Network Graphs and Dual‐venc 4D Flow MRI

“…The distribution of CoW variants is consistent with population studies showing about a 0.6% prevalence of unilaterally absent PCOM, but 34% prevalence of unilaterally hypoplastic PCOM, which may contribute little hemodynamically. Notably, a previous 4D flow study found a 24–29% prevalence of variant anatomies in healthy controls (middle‐aged and older) vs. 38% in Alzheimer's disease patients in addition to significant differences in arterial PI between the groups . This suggests that flow distribution differences between these variants may have clinical significance, which may be clarified by larger cohort studies with FDNG.…”

Intracranial Arterial 4D Flow in Individuals with Mild Cognitive Impairment is Associated with Cognitive Performance and Amyloid Positivity

“…Participants were selected from a large cohort, the WADRC, consisting of approximately 700 individuals spanning the AD spectrum: middle-aged participants both with and without a family history of AD, cognitively healthy older control participants, and subjects with clinically diagnosed MCI and AD [11, 13]. Participants with MCI are recruited primarily from local clinics (or control subjects in longitudinal studies that have shown cognitive decline) and diagnosis is confirmed by clinical consensus conference based on established clinical criteria [1, 21].…”

“…Furthermore, the technique facilitates measurements of flow, pulsatility, and vessel area that can be determined retrospectively. Using this technique, we have previously shown decreased mean blood flow and increased pulsatility (a metric of vessel stiffness) in the intracranial arteries, from cognitively healthy middle-aged individuals, to cognitively healthy older adults and lastly to clinically diagnosed MCI and AD patients [11]. Rivera-Rivera and colleagues extended this to examine the properties of the venous system, particularly flow and pulsatility, in the superior sagittal sinus, straight sinus, and transverse sinus.…”