• Vince I Madai, Steve Z Martin, Federico C von Samson-Himmelstjerna, Cornelius X Herzig, Matthias A Mutke, Carla N Wood, Thoralf Thamm, Sarah Zweynert, Miriam Bauer, Stefan Hetzer, GüntherMatthiasMFraunhofer MEVIS, Bremen, Germany.University Bremen, Bremen, Germany.mediri GmbH, Heidelberg, Germany., and Jan Sobesky.
• Center for Stroke Research Berlin (CSB), Charité-Universitätsmedizin, Berlin, Germany.
• J Neuroimaging. 2016 Jul 1; 26 (4): 436-44.

Background And PurposeArterial spin labeling (ASL) is an MRI technique to measure cerebral blood flow (CBF) without the need of exogenous contrast agents and is thus a promising alternative to the clinical standard dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion imaging. Latest international guidelines encourage its application in the clinical setting. However, susceptibility-induced image distortions impair ASL with fast readout modules (eg Echo Planar Imaging, EPI; gradient and spin echo, GRASE). In the present study, we investigated the benefit of a distortion correction for ASL compared to DSC.MethodsA pulsed ASL (PASL) sequence combined with a 3D-GRASE readout at multiple inflow times (multi-TI) was used and was corrected for susceptibility distortions using a FMRIB Software Library (FSL) implemented tool TOPUP. We performed qualitative (three expert raters) and quantitative (volume of interest [VOI]-based) comparisons of ASL and DSC imaging in 13 patients with chronic steno-occlusive disease.ResultsIn the qualitative analysis, distortion correction of the images led to a strong increase in diagnostic precision of ASL compared to DSC in the anterior cerebral artery (ACA) perfusion territory, where the susceptibility artifact was most pronounced (specificity 8% vs. 75%). In the quantitative analysis, the correlation between ASL and DSC values increased for all perfusion territories with the best improvement for the ACA territory (for anterior, middle and posterior cerebral artery: ACA: rho -0.22 vs. 0.71; MCA: rho 0.58 vs. 0.76; PCA: rho 0.58 vs. 0.63).ConclusionsWe showed that susceptibility distortion correction strongly improves the comparability of multi-TI ASL 3D-GRASE to DSC in steno-occlusive disease. We suggest it to be implemented in ASL postprocessing routines.Copyright © 2016 by the American Society of Neuroimaging.

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