Cerebral Perfusion Measurements in Elderly with Hypertension Using Arterial Spin Labeling

Abstract

PurposeThe current study assesses the feasibility and value of crushed cerebral blood flow (CBFcrushed) and arterial transit time (ATT) estimations for large clinical imaging studies in elderly with hypertension.Material and MethodsTwo pseudo-continuous arterial spin labeling (ASL) scans with (CBFcrushed) and without flow crushers (CBFnon-crushed) were performed in 186 elderly with hypertension, from which CBF and ATT maps were calculated. Standard flow territory maps were subdivided into proximal, intermediate and distal flow territories, based on the measured ATT. The coefficient of variation (CV) and physiological correlations with age and gender were compared between the three perfusion parameters.ResultsThere was no difference in CV between CBFcrushed and CBFnon-crushed (15–24%, p>0.4) but the CV of ATT (4–9%) was much smaller. The total gray matter correlations with age and gender were most significant with ATT (p = .016 and p<.001 respectively), in between for CBFcrushed (p = .206 and p = .019) and least significant for CBFnon-crushed (p = .236 and p = .100).ConclusionThese data show the feasibility and added value of combined measurements of both crushed CBF and ATT for group analyses in elderly with hypertension. The obtained flow territories provide knowledge on vascular anatomy of elderly with hypertension and can be used in future studies to investigate regional vascular effects.

Effects of arterial transit delay on cerebral blood flow quantification using arterial spin labeling in an elderly cohort

“…Our study bears similarities to the recent study of Mutsaerts et al that used a gradient dephasing approach to estimate ATT in an elderly cohort with hypertension. Qualitatively similar spatial distributions of transit time were observed and some improvement in coefficient of variation was observed with ATT correction.…”

“…Pulsed ASL techniques have been used to measure several hemodynamic parameters including a measure of ATT and have been applied to comparisons of Alzheimer's disease groups with matched elderly controls . Recently a flow dephasing continuous ASL approach has been used to characterize transit times and their variability in an elderly cohort with hypertension …”

Temporal and Spatial Variances in Arterial Spin-Labeling Are Inversely Related to Large-Artery Blood Velocity

“…24,25 Thus, labeled blood is more likely to remain in the macrovascular compartment and be captured as hyperintense signal, contributing to greater heterogeneity within the perfusion-weighted image. 26 Indeed, a recent ASL study in hypertensive older adults demonstrated a direct relationship between single postlabel delay spatial CoV and arterial transit time. 17 To combat this, longer postlabel delays are recommended for imaging older adults to allow signal to reach the tissue before acquisition, albeit at a cost of lower signal intensity.…”

White Matter Hyperintensity Volume and Cerebral Perfusion in Older Individuals with Hypertension Using Arterial Spin-Labeling

“…ATT may be less physiologically variable and thereby a more sensitive marker of these slight differences. 27 Furthermore, because in arterial spinlabeling, longer ATT may cause lower CBF estimates, especially distally, the association between ATT and WMH volume may have affected our WMH CBF estimates. 32 However, adjustment for ATT alone did not much affect the association between WMH CBF and WMH volume.…”

“…(postdoctoral researcher, 6 years of experience) and are described in more detail elsewhere. 27 In short, T1-weighted images were segmented into GM and WM probability maps. After motion correction, 2 ϫ 20 pairs of arterial spin-labeled and control images were pair-wise subtracted and subsequently averaged to gen-erate perfusion-weighted maps, which were converted to milliliter/100 g/min by using a single compartment model.…”