Improved olefinic fat suppression in skeletal muscle DTI using a magnitude-based dixon method

PurposeTo develop a method of suppressing the multi-resonance fat signal in diffusion-weighted imaging of skeletal muscle. This is particularly important when imaging patients with muscular dystrophies, a group of diseases which cause gradual replacement of muscle tissue by fat.Theory and MethodsThe signal from the olefinic fat peak at 5.3 ppm can significantly confound diffusion-tensor imaging measurements. Dixon olefinic fat suppression (DOFS), a magnitude-based chemical-shift-based method of suppressing the olefinic peak, is proposed. It is verified in vivo by performing diffusion tensor imaging (DTI)-based quantification in the lower leg of seven healthy volunteers, and compared to two previously described fat-suppression techniques in regions with and without fat contamination.ResultsIn the region without fat contamination, DOFS produces similar results to existing techniques, whereas in muscle contaminated by subcutaneous fat signal moved due to the chemical shift artefact, it consistently showed significantly higher (P=0.018) mean diffusivity (MD). Because fat presence lowers MD, this suggests improved fat suppression.ConclusionDOFS offers superior fat suppression and enhances quantitative measurements in the muscle in the presence of fat. DOFS is an alternative to spectral olefinic fat suppression. Magn Reson Med 79:152-159, 2018. (c) 2017 International Society for Magnetic Resonance in Medicine