Single-shot Trace Diffusion Weighted Radial Spectroscopic Imaging of Human Calf Muscle: Intra-/Extra-myocellular Lipids and Metabolites

Motivation: To investigate the diffusion of calf muscle intra-myocellular droplets in diabetes and obesity. Goal(s): To validate diffusion-weighted radial echo-planar spectroscopic imaging (DW-REPSI) in calf muscle. Approach: We acquired DW-REPSI spectra using 2 different b-values in 3 young healthy subjects and one type2 diabetic patient; regional variations of intra- and extra- myocellular lipids (IMCL and EMCL), creatine and trimethylamines (TMA) and their diffusivities were quantified. Results: Decreased TMA was recorded in the tibialis anterior muscle compared to that of soleus and gastronomic muscles. ADCs of IMCL and EMCL and metabolites were quantified. Lower ADCs of IMCL indicated restricted motion. Shifts in EMCL was observed. Impact: A diffusion-weighted spectroscopic imaging sequence was evaluated to investigate the diffusion characteristics and regional variations of IMCL, EMCL and metabolites in calf muscle. The outcome may provide new biophysical insights in the investigation of lipid metabolism in diabetes.