A method for fat suppression in MRI based on diffusion-weighted imaging

The diffusion coefficient of lipid molecules is usually much smaller than that of water, and it is demonstrated here how this difference can be exploited for robust fat suppression in magnetic resonance imaging (MRI). In contrast to the prevailing methods, diffusion-based fat suppression does not rely on chemical shift differences between water and lipids and can therefore be applied easily in low or inhomogeneous magnetic fields. It is also independent of relaxation times and can therefore be incorporated in experiments requiring conventional T1-weighted contrast. Diffusion-based fat suppression (DIFFSUP) consists of subtracting the signals acquired at low and high b-values, where the high b-value is ideally designed to achieve full suppression of the water and negligible attenuation of the lipid signal. Since high b-value images may be particularly affected by motion artifacts, a version of DIFFSUP incorporating first-order velocity compensation is also proposed and demonstrated. Results from phantoms and live mice at field strengths of 4.7 T and 1.0 T are presented.