Quantitative measurement of creatine content in skeletal muscle using 1H-MRS

We obtained ¹H magnetic resonance spectra of skeletal muscles, with and without atrophy, and quantitatively evaluated the content of creatine in the muscles. Wister rats at nine weeks old were subjected to sciatic nerve transection of the left hindlimb which caused neurogenic muscular atrophy at the left gastrocnemius muscle. The spectra were acquired from a 2×2×2-mm³ voxel located on the left gastrocnemius muscle with arrayed repetition times (TR) and echo times (TE). The signal intensities and the relaxation times of water and creatine were estimated by fitting a model equation to the measured spectra. The content of creatine was estimated from the signal intensities, the relaxation times, and the content of water. There was no significant difference in the relaxation times of water and creatine between the denervated group and the control group. The water content of the denervated group was significantly smaller than that of the control group (p<0.01). The creatine content of the denervated group was smaller than that of the control group, though the difference was not statistically significant. This method is useful for quantifying the creatine content on the order of 10^-3 mol/kg.