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ABSTRACT: Purpose
To further optimize the velocity-selective arterial spin labeling (VSASL) sequence utilizing a Fourier-transform based velocity-selective inversion (FT-VSI) pulse train, and to evaluate its utility for 3D mapping of cerebral blood flow (CBF) with a gradient- and spin-echo (GRASE) readout.Methods
First, numerical simulations and phantom experiments were done to test the susceptibility to eddy currents and B1 field inhomogeneities for FT-VSI pulse trains with block and composite refocusing pulses. Second, the choices of the post-labeling delay (PLD) for FT-VSI prepared 3D VSASL were evaluated for the sensitivity to perfusion signal. The study was conducted among a young-age and a middle-age group at 3T. Both signal-to-noise ratio (SNR) and CBF were quantitatively compared with pseudo-continuous ASL (PCASL). The optimized 3D VSI-ASL was also qualitatively compared with PCASL in a whole-brain coverage among two healthy volunteers and a brain tumor patient.Results
The simulations and phantom test showed that composite refocusing pulses are more robust to both eddy-currents and B1 field inhomogeneities than block pulses. 3D VSASL images with FT-VSI preparation were acquired over a range of PLDs and PLD = 1.2 s was selected for its higher perfusion signal. FT-VSI labeling produced quantitative CBF maps with 27% higher SNR in gray matter compared to PCASL. 3D whole-brain CBF mapping using VSI-ASL were comparable to the corresponding PCASL results.Conclusion
FT-VSI with 3D-GRASE readout was successfully implemented and showed higher sensitivity to perfusion signal than PCASL for both young and middle-aged healthy volunteers.
SUBMITTER: Liu D
PROVIDER: S-EPMC7402012 | biostudies-literature | 2020 Nov
REPOSITORIES: biostudies-literature
Liu Dapeng D Xu Feng F Li Wenbo W van Zijl Peter C PC Lin Doris D DD Qin Qin Q
Magnetic resonance in medicine 20200513 5
<h4>Purpose</h4>To further optimize the velocity-selective arterial spin labeling (VSASL) sequence utilizing a Fourier-transform based velocity-selective inversion (FT-VSI) pulse train, and to evaluate its utility for 3D mapping of cerebral blood flow (CBF) with a gradient- and spin-echo (GRASE) readout.<h4>Methods</h4>First, numerical simulations and phantom experiments were done to test the susceptibility to eddy currents and B<sub>1</sub> field inhomogeneities for FT-VSI pulse trains with blo ...[more]