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Abstract #2024

Optimizing pseudo-continuous ASL at 7 Tesla using dynamic low order-shim update

Yulin Chang1, Jason Stockmann2,3, Marta Vidorreta4, Natalie Wheeler2, Andreas Potthast5, Thomas Benner5, Manuel Taso1, John A Detre6,7, and Meher R Juttukonda2,3
1Siemens Medical Solutions USA Inc., Malvern, PA, United States, 2A.A. Martinos Center of Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, 3Harvard Medical School, Boston, MA, United States, 4Siemens S.A., Madrid, Spain, 5Siemens Healthcare GmbH, Erlangen, Germany, 6Department of Neurology, University of Pennsylvania, Philadelphia, PA, United States, 7Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States

Synopsis

Keywords: Perfusion, Arterial spin labelling, shims

Motivation: The labeling efficiency of pseudo-continuous ASL (pCASL) is reduced in the presence of large B0 off-resonance, which makes pCASL challenging at ultra-high fields due to susceptibility-induced off-resonance.

Goal(s): We aim to significantly reduce the labeling efficiency dependence on B0 off-resonance of pCASL to achieve highest allowed labeling efficiency at a given labeling flip angle.

Approach: 0th- (frequency) and 1st-order (x,y,z) shim components were used dynamically in the duration of labeling to mitigate B0 off-resonance without affecting imaging readout.

Results: Improved labeling efficiency was achieved, which enabled higher-resolution perfusion imaging using pCASL. Selective labeling of blood was also demonstrated possible using our approach.

Impact: Our approach provides a simple method to substantially remove the labeling-efficiency dependence on B0 off-resonance for pCASL at 7T. This enables high-quality ASL-based perfusion imaging at ultra-high fields for study of brain function, physiology, and pathology.

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Keywords