Gray matter contamination in arterial spin labeling white matter perfusion measurements in patients with dementia

Abstract

IntroductionWhite matter (WM) perfusion measurements with arterial spin labeling can be severely contaminated by gray matter (GM) perfusion signal, especially in the elderly. The current study investigates the spatial extent of GM contamination by comparing perfusion signal measured in the WM with signal measured outside the brain.Material and methodsFour minute 3T pseudo-continuous arterial spin labeling scans were performed in 41 elderly subjects with cognitive impairment. Outward and inward geodesic distance maps were created, based on dilations and erosions of GM and WM masks. For all outward and inward geodesic distances, the mean CBF was calculated and compared.ResultsGM contamination was mainly found in the first 3 subcortical WM voxels and had only minor influence on the deep WM signal (distances 4 to 7 voxels). Perfusion signal in the WM was significantly higher than perfusion signal outside the brain, indicating the presence of WM signal.ConclusionThese findings indicate that WM perfusion signal can be measured unaffected by GM contamination in elderly patients with cognitive impairment. GM contamination can be avoided by the erosion of WM masks, removing subcortical WM voxels from the analysis. These results should be taken into account when exploring the use of WM perfusion as micro-vascular biomarker.

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

“…42,43 However, although current arterial spin-labeling techniques may be unable to measure WM CBF with high accuracy on a voxel-level, on an ROI level, as used in this study, it has been shown that WM CBF can be measured within a scanning time of as little as 5 minutes. [44][45][46] Our measurements were precise enough to measure significant differences in CBF between the NAWM and WMH and between the whole WM and the NAWM only. Moreover, the reliability of our findings is supported by the ratios between the GM, WM, NAWM, and WMH CBF, which are similar to those reported in studies in which exogenous contrast agents were used.…”

Multi-vendor reliability of arterial spin labeling perfusion MRI using a near-identical sequence: Implications for multi-center studies

“…WM masks were threefold eroded to avoid GM contamination (Mutsaerts et al, 2013). ROIs of anterior, middle and posterior flow territories (supplied by the anterior, middle and posterior cerebral artery respectively) were created from standard vascular territory templates (Tatu et al, 1998) and ROIs associated with age-related dementia (anterior and posterior cingulate, precuneus) were created from the Wake Forest University Pick-atlas (http://fmri.wfubmc.edu/cms/software).…”

Accelerated white matter aging in schizophrenia: role of white matter blood perfusion

“…A GM perfusion map was calculated by multiplying the average perfusion mask by the participant’s binary GM tissue map. The WM perfusion map was calculated by applying a participant’s binary WM tissue map that was eroded with a 10-mm spherical kernel to reduce contamination of WM CBF due to partial voxel averaging to the average perfusion map (Mutsaerts et al 2013). Tract-wise ROIs from the JHU atlas were used to calculate average CBF WM and FA values along the spatial course of the twelve major WM tracts.…”