• Steve Z Martin, Vince I Madai, Federico C von Samson-Himmelstjerna, Matthias A Mutke, Miriam Bauer, Cornelius X Herzig, Stefan Hetzer, GüntherMatthiasM1] Fraunhofer MEVIS, Institute for Medical Image Computing, Bremen, Germany [2] Faculty of Physics and Electronics, University of Bremen, Bremen, Germany [3] mediri GmbH, Heidelberg, Germany., and Jan Sobesky.
• Center for Stroke Research Berlin (CSB), Charité-Universitätsmedizin, Berlin, Germany.
• J. Cereb. Blood Flow Metab. 2015 Mar 1; 35 (3): 392-401.

AbstractPulsed arterial spin labeling (PASL) at multiple inflow times (multi-TIs) is advantageous for the measurement of brain perfusion in patients with long arterial transit times (ATTs) as in steno-occlusive disease, because bolus-arrival-time can be measured and blood flow measurements can be corrected accordingly. Owing to its increased signal-to-noise ratio, a combination with a three-dimensional gradient and spin echo (GRASE) readout allows acquiring a sufficient number of multi-TIs within a clinically feasible acquisition time of 5 minutes. We compared this technique with the clinical standard dynamic susceptibility-weighted contrast-enhanced imaging-magnetic resonance imaging in patients with unilateral stenosis >70% of the internal carotid or middle cerebral artery (MCA) at 3 Tesla. We performed qualitative (assessment by three expert raters) and quantitative (region of interest (ROI)/volume of interest (VOI) based) comparisons. In 43 patients, multi-TI PASL-GRASE showed perfusion alterations with moderate accuracy in the qualitative analysis. Quantitatively, moderate correlation coefficients were found for the MCA territory (ROI based: r=0.52, VOI based: r=0.48). In the anterior cerebral artery (ACA) territory, a readout related right-sided susceptibility artifact impaired correlation (ROI based: r=0.29, VOI based: r=0.34). Arterial transit delay artifacts were found only in 12% of patients. In conclusion, multi-TI PASL-GRASE can correct for arterial transit delay in patients with long ATTs. These results are promising for the transfer of ASL to the clinical practice.

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