Can arterial spin labeling detect white matter perfusion signal?

Abstract

Since the invention of arterial spin labeling (ASL) it has been acknowledged that ASL does not allow reliable detection of a white matter (WM) perfusion signal. However, recent developments such as pseudo-continuous labeling and background suppression have improved the quality. The goal of this research was to study the ability of these newer ASL sequences to detect WM perfusion signal. Background suppressed pseudo-continuous ASL was implemented at 3T with multislice 2D readout after 1525 ms. In five volunteers it was shown that 10 min scanning resulted in significant perfusion signal in 70% of WM voxels. Increasing the labeling and delay time did not lead to a higher percentage. In 27 normal volunteers it was found that 35 averages are necessary to detect significant WM signal, but 150 averages are needed to detect signal in the deep WM. Finally, it was shown in a patient with a cerebral arteriovenous malformation that pseudo-continuous ASL enabled the depiction of hypointense WM perfusion signal, although dynamic susceptibility contrast MRI showed that this region was merely showing delayed arrival of contrast agent than hypoperfusion. It can be concluded that, except within the deep WM, ASL is sensitive enough to detect WM perfusion signal and perfusion deficits. Magn Reson Med 62:165-173, 2009.

Arterial spin labeling measurement of cerebral perfusion in children with sickle cell disease

“…Finally, it might have been interesting to analyze white matter perfusion since most ischemic lesions are located in the deep white matter. However, the scanning times we used were too short for this purpose, as longer scanning times (%10 min) are necessary to measure significant white matter perfusion in single voxels in the deep white matter (41). In an additional analysis, we observed that asymmetries were more prominent in the white matter perfusion in patients, but similar to the gray matter asymmetries no association with pathology could be observed.…”

Age‐related cerebral perfusion changes in the parietal and temporal lobes measured by pulsed arterial spin labeling

“…Potential sources of systematic errors are violations of the model assumptions. Especially, the crucial role of the arterial transit time dt is frequently emphasized (13,37,38). Actually, CBF quantification requires measurements at several inversion times to concomitantly estimate the spatially variable arterial transit times (13) but this would multiply measurement time which is prohibitive for clinical studies in elderly patient populations.…”

“…However, in some areas, e.g., the occipital cortex the combination of prolonged transit times (29) and relatively short TI2 might lead to artificially high CBF estimates when labeled blood is still in arterial vessels during readout. Please note that we did not consider CBF in WM because prolonged transit times are considered to prohibit reliable CBF measurements (38). In the basal ganglia, especially in the pallidum and putamen, CBF quantification may be additionally hampered by short T2* values due to iron deposition.…”

Cerebrovascular Reactivity in the Brain White Matter: Magnitude, Temporal Characteristics, and Age Effects

“…9 Recent technical advances in imaging methodologies have mitigated some of these problems and provided the potential to examine vascular physiology in the WM. 10 For example, it has been suggested that baseline cerebral blood flow (CBF) of WM can be quantitatively assessed with arterial-spin-labeling (ASL) MRI on a region-by-region and tract-by-tract basis and that WM CBF is inversely correlated with diffusion fractional anisotropy. 10,11 The present study is focused on the examination of another important property of microvasculature: its ability to dilate on stimulation.…”

“…10 For example, it has been suggested that baseline cerebral blood flow (CBF) of WM can be quantitatively assessed with arterial-spin-labeling (ASL) MRI on a region-by-region and tract-by-tract basis and that WM CBF is inversely correlated with diffusion fractional anisotropy. 10,11 The present study is focused on the examination of another important property of microvasculature: its ability to dilate on stimulation. This physiologic property, referred to as cerebrovascular reactivity (CVR), [12][13][14] is a critical function of healthy blood vasculature.…”