Improved velocity-selective labeling pulses for myocardial ASL

Vanessa Landes, Ahsan Javed, Terrence Jao, Qin Qin, Krishna Nayak

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: To develop and evaluate an improved velocity-selective (VS) labeling pulse for myocardial arterial spin labeling (ASL) perfusion imaging that addresses two limitations of current pulses: (1) spurious labeling of moving myocardium and (2) low labeling efficiency. Methods: The proposed myocardial VSASL labeling pulse is designed using a Fourier Transform based Velocity-Selective labeling pulse train. The pulse utilizes bipolar velocity-encoding gradients, a 9-tap velocity-encoding envelope, and double-refocusing pulses with Malcolm Levitt phase cycling. Amplitudes of the velocity-encoding envelope were optimized to minimize the labeling of myocardial velocities during stable diastole (±2-3 cm/s) and maximize the labeling of coronary velocities (10-130 cm/s during rest/stress or 10-70 cm/s during rest). Myocardial ASL experiments were performed in seven healthy subjects using the previously developed VS-ASL protocol by Jao et al with the two proposed VS pulses and original VS pulse. Myocardial ASL experiments were also performed using FAIR ASL. Myocardial perfusion and physiological noise (PN) were evaluated and compared. Results: Bloch simulations of the first and second proposed pulses show <2% labeling over ±3 cm/s and ±2 cm/s, respectively. Bloch simulations also show the mean labeling efficiency of arterial blood is 1.23 over the relevant coronary arterial ranges. In-vivo VSASL experiments show the proposed pulses provided comparable measurements to FAIR ASL and reduced TSNR in 5 of 7 subjects compared to the original VS pulse. Conclusion: We demonstrate an improved VS labeling pulse specifically for myocardial ASL perfusion imaging to reduce spurious labeling of moving myocardium and PN.

Original languageEnglish (US)
Pages (from-to)1909-1918
Number of pages10
JournalMagnetic resonance in medicine
Volume84
Issue number4
DOIs
StatePublished - Oct 1 2020

Keywords

  • RF pulse design
  • arterial spin labeling
  • myocardial perfusion
  • velocity selective ASL
  • velocity-selective labeling

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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