In vivo T1 characterization of genetically induced muscle atrophy

In vivo spin-lattice relaxation times, T1, of water and lipid protons of normal and atrophic muscles were measured, using the spatially resolved spectroscopy (SPARS) sequence, in a genetic avian model of myopathy. These T1 values were compared with those of the hypertrophic muscles. Although the water T1 values of muscles were elevated in both types of lesions, the atrophic muscles showed a greater increase (54%) than the hypertrophic muscles (22%). The water T1 differentiation between the atrophic and hypertrophic muscles appeared to depend upon their bound water fractions that were calculated on the basis of the Fast Proton Diffusion model. The lipid T1 values of muscles were higher in the atrophic line of chickens compared to their genetic controls. In contrast, the lipid T1 values of muscles of the hypertrophic chickens and their controls were essentially identical. This suggests that the lipid T1 values may potentially complement the water T1 values in the differential diagnosis of muscle disorders.