Investigating white matter perfusion using optimal sampling strategy arterial spin labeling at 7 Tesla

E-ISSN： 1522-2594|73|6|2243-2248

ISSN： 0740-3194

Source： MAGNETIC RESONANCE IN MEDICINE, Vol.73, Iss.6, 2015-06, pp. : 2243-2248

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Abstract

PurposeCerebral blood flow (CBF) is an informative physiological marker for tissue health. Arterial spin labeling (ASL) is a noninvasive MRI method of measuring this parameter, but it has proven difficult to measure white matter (WM) CBF due to low intrinsic contrast‐to‐noise ratio compared with gray matter (GM). Here we combine ultra‐high field and optimal sampling strategy (OSS) ASL to investigate WM CBF in reasonable scan times.MethodsA FAIR‐based ASL sequence at 7T was combined with a real‐time‐feedback OSS technique, to iteratively improve post‐label image acquisition times (TIs) on a tissue‐ and subject‐specific basis to obtain WM CBF quantification.ResultsIt was found 77% of WM voxels gave a reasonable CBF fit. Averaged WM CBF for these voxels was found to be 16.3 ± 1.5 mL/100 g/min (discarding partial‐volumed voxels). The generated TI schedule was also significantly different when altering the OSS weighted‐tissue‐mask, favoring longer TIs in WM.ConclusionWM CBF could be reasonably quantified in over 75% of identified voxels, from a total preparation and scan time of 15 min. OSS results suggest longer TIs should be used versus general GM ASL settings; this may become more important in WM disease studies. Magn Reson Med 73:2243–2248, 2015. © 2014 Wiley Periodicals, Inc.