A simple approach for improving lipid SNR for hepatic fat measurement with 1H MRS

Introduction Assessing lipid content in liver is of interest for number of pathologies and for observation of metabolic changes during therapy [1]. Magnetic resonance spectroscopy (MRS) is rapidly becoming the method of choice for non-invasive assessment of lipids in liver [2]. To avoid artifacts due to liver motion, MRS is often performed with a breath-hold approach [3, 4]. Given this limited amount of time available to perform the acquisition, it is of interest to maximize the signal-to-noise ratio (SNR) per unit time of the fat resonances, since the fat tissue levels are one to two orders of magnitude lower than water tissue levels. Previous studies [1-4] have used repetition times (TR) of 1.5-2 seconds, which is more optimized for water SNR. We hypothesized that, by a proper choice of a shorter TR, it might be possible to substantially increase the fat SNR in breath-hold MRS of liver, and thereby increase the precision of the calculation of the fat content in the voxel.