Journal
MAGNETIC RESONANCE IN MEDICINE
Volume 73, Issue 3, Pages 1085-1094Publisher
WILEY
DOI: 10.1002/mrm.25227
Keywords
arterial spin labeling; BIR-8; eddy current; perfusion; velocity-selective ASL
Funding
- NIH [R01 EB002096]
- Cancer Research UK
- Engineering and Physical Sciences Research Council
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PurposeVelocity-selective arterial spin labeling (VSASL) tags arterial blood on a velocity-selective (VS) basis and eliminates the tagging/imaging gap and associated transit delay sensitivity observed in other ASL tagging methods. However, the flow-weighting gradient pulses in VS tag preparation can generate eddy currents (ECs), which may erroneously tag the static tissue and create artificial perfusion signal, compromising the accuracy of perfusion quantification. MethodsA novel VS preparation design is presented using an eight-segment B-1 insensitive rotation with symmetric radio frequency and gradient layouts (sym-BIR-8), combined with delays after gradient pulses to optimally reduce ECs of a wide range of time constants while maintaining B-0 and B-1 insensitivity. Bloch simulation, phantom, and in vivo experiments were carried out to determine robustness of the new and existing pulse designs to ECs, B-0, and B-1 inhomogeneity. ResultsVSASL with reduced EC sensitivity across a wide range of EC time constants was achieved with the proposed sym-BIR-8 design, and the accuracy of cerebral blood flow measurement was improved. ConclusionThe sym-BIR-8 design performed the most robustly among the existing VS tagging designs, and should benefit studies using VS preparation with improved accuracy and reliability. Magn Reson Med 73:1085-1094, 2015. (c) 2014 Wiley Periodicals, Inc.
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