Vanessa Landes1, Ahsan Javed2, Terrence Jao3, Qin Qin4,5, Krishna Nayak1,2. 1. Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angles, CA, USA. 2. Ming Hsieh Department of Electrical and Computer Engineering, Viterbi School of Engineering, University of Southern California, Los Angles, CA, USA. 3. Keck School of Medicine, University of Southern California, Los Angles, CA, USA. 4. The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, John Hopkins University School of Medicine, Baltimore, MD, USA. 5. F.M. Kirby Research Center for Functional Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
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.
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.
Authors: Isabell K Bones; Suzanne L Franklin; Anita A Harteveld; Matthias J P van Osch; Sophie Schmid; Jeroen Hendrikse; Chrit Moonen; Marijn van Stralen; Clemens Bos Journal: Magn Reson Med Date: 2021-02-04 Impact factor: 4.668
Authors: Qin Qin; David C Alsop; Divya S Bolar; Luis Hernandez-Garcia; James Meakin; Dapeng Liu; Krishna S Nayak; Sophie Schmid; Matthias J P van Osch; Eric C Wong; Joseph G Woods; Greg Zaharchuk; Moss Y Zhao; Zungho Zun; Jia Guo Journal: Magn Reson Med Date: 2022-07-12 Impact factor: 3.737