Investigation of Spatial-Spectral Selective Pulses for B1 Compensation and Improved Saturation Homogeneity in Cardiac CEST MRI

Abstract

Chemical Exchange Saturation Transfer (CEST) MRI is highly susceptible to B1 inhomogeneities, resulting in inconsistent contrast for tissues with equal metabolite concentrations. To enhance B1-uniformity of saturation across the myocardium, a spectral-spatially selective pulse for CEST preparation was tailored for each subject. Simulations showed the tailored pulse reduced B1 variation from 6.85⁰ to 2.9⁰. These results were investigated on a Siemens 3T Trio scanner by performing full cardiac CEST exams using a conventional Gaussian or a tailored pulse for saturation. The tailored pulse resulted in reduced water and MT contrast variation across the myocardium when compared to the conventional pulse.