Ensuring both velocity and spatial responses robust to B0/B1+ field inhomogeneities for velocity-selective arterial spin labeling through dynamic phase-cycling

Dapeng Liu, Wenbo Li, Feng Xu, Dan Zhu, Taehoon Shin, Qin Qin

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: To evaluate both velocity and spatial responses of velocity-selective arterial spin labeling (VS-ASL), using velocity-insensitive and velocity-compensated waveforms for control modules, as well as a novel dynamic phase-cycling approach, at different B0/ (Formula presented.) field inhomogeneities. Methods: In the presence of imperfect refocusing, the mechanism of phase-cycling the refocusing pulses through four dynamics was first theoretically analyzed with the conventional velocity-selective saturation (VSS) pulse train. Numerical simulations were then deployed to compare the performance of the Fourier-transform based velocity-selective inversion (FT-VSI) with these three different schemes in terms of both velocity and spatial responses under various B0/ (Formula presented.) conditions. Phantom and human brain scans were performed to evaluate the three methods at (Formula presented.) scales of 0.8, 1.0, and 1.2. Results: The simulations of FT-VSI showed that, under nonuniform B0/ (Formula presented.) conditions, the scheme with velocity-insensitive control was susceptible to DC bias of the static spins as systematic error, while the scheme with velocity-compensated control had deteriorated velocity-selective labeling profiles and, thus, reduced labeling efficiency. Through numerical simulation, phantom scans, and brain perfusion measurements, the dynamic phase-cycling method demonstrated considerable improvements over these issues. Conclusion: The proposed dynamic phase-cycling approach was demonstrated for the velocity-selective label and control modules with both velocity and spatial responses robust to a wide range of B0 and (Formula presented.) field inhomogeneities.

Original languageEnglish (US)
Pages (from-to)2723-2734
Number of pages12
JournalMagnetic resonance in medicine
Volume85
Issue number5
DOIs
StateAccepted/In press - 2020

Keywords

  • B field inhomogeneity
  • B1+ field inhomogeneity
  • arterial spin labeling
  • cerebral blood flow
  • velocity-selective inversion

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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