The effects of concomitant gradients on chemical shift encoded MRI

Abstract

Purpose The purpose of this work was to characterize the effects of concomitant gradients (CGs) on chemical shift encoded (CSE)-based estimation of B0 field map, proton density fat fraction (PDFF), and . Theory A theoretical framework was used to determine the effects of CG-induced phase errors on CSE-MRI data. Methods Simulations, phantom experiments, and in vivo experiments were conducted at 3 Tesla to assess the effects of CGs on quantitative CSE-MRI techniques. Correction of phase errors attributable to CGs was also investigated to determine whether these effects could be removed. Results Phase errors attributed to CGs introduce errors in the estimation of B0 field map, PDFF, and . Phantom and in vivo experiments demonstrated that CGs can introduce estimation errors greater than 30 Hz in the B0 field map, 10% in PDFF, and 16 s−1 in , 16 cm off isocenter. However, CG phase correction before parameter estimation was able to reduce estimation errors to less than 10 Hz in the B0 field map, 1% in PDFF, and 2 s−1 in . Conclusion CG effects can impact CSE-MRI, leading to inaccurate estimation of B0 field map, PDFF, and . However, correction for phase errors caused by CGs improve the accuracy of quantitative parameters estimated from CSE-MRI acquisitions. Magn Reson Med 78:730–738, 2017. © 2016 International Society for Magnetic Resonance in Medicine