Saturation recovery single-shot acquisition (SASHA) for myocardial T 1 mapping

Abstract

Purpose: To validate a new saturation recovery single-shot acquisition (SASHA) pulse sequence for T1 mapping and to compare SASHA T 1 values in heart failure patients and healthy controls. Theory: The SASHA sequence consists of 10 electrocardiogram-triggered single-shot balanced steady-state free precession images in a breath-hold. The first image is acquired without magnetization preparation and the remaining nine images follow saturation pulses with variable saturation recovery times. Methods: SASHA was validated through Bloch equation simulations, Monte Carlo simulations, and phantom experiments. Pre- and postcontrast myocardial and blood T1 values were measured in 29 healthy volunteers and 7 patients with heart failure. Results: SASHA T1 values had excellent agreement (bias, 5 ± 5 ms) with spin echo experiments in phantoms with a wide range of physiologic T1 and T2 values and its accuracy was independent of flip angle, absolute T1, T2, and heart rate. The average baseline myocardial T1 in heart failure patients was higher than in healthy controls (1200 ± 32 vs. 1170 ± 9 ms, P < 0.05) at 1.5T, as was the calculated blood-tissue partition coefficient, λ, (0.42 ± 0.04 vs. 0.38 ± 0.02, P < 0.05), consistent with diffuse myocardial fibrosis. Conclusions: The SASHA sequence is a simple and fast approach to in vivo T1 mapping with good accuracy in simulations and phantom experiments. © 2013 Wiley Periodicals, Inc.