Fat-water MRI is sensitive to local adipose tissue inflammatory changes in a diet-induced obesity mouse model at 15T

Abstract

In obesity, fat-water MRI (FWMRI) methods provide valuable information about adipose tissue (AT) distribution. AT is known to undergo complex metabolic and endocrine changes in association with chronic inflammation including iron overloading. Here, we investigate the potential for FWMRI parameters (fat signal fraction (FSF), local magnetic field offset, and T 2 *) to be sensitive to AT inflammatory changes in an established diet-induced obesity mouse model. Male C57BL/6J mice were placed on a low fat (LFD) or a high fat diet (HFD). 3D multi- gradient-echo MRI at 15.2T was performed at baseline, 4, 8, 12, and 16 weeks after diet onset. A 3D fat-water separation algorithm and additional processing was used to generate FSF, local field offset, and T 2 * maps. We examined these parameters in perirenal AT ROIs from HFD and LFD mice. Results: The data suggest that FSF, local field offset, and T 2 * can differentiate time course behavior between inflamed and control AT (increasing FSF, decreasing local field offset, increasing followed by decreasing T 2 *). The biophysical mechanisms of these observed changes are not well understood and require further study. To the best of our knowledge, we report the first evidence that FWMRI can provide biomarkers sensitive to AT inflammation, and that FWMRI has the potential for longitudinal non-invasive assessment of AT inflammation in obesity.