Objective parameters in magnetic resonance imaging (MRI) for neuromuscular diagnosis: preliminary findings

T1 relaxation time (T1 time), T2 relaxation time (T2 time), and proton (rho) density in the thigh muscles of 20 normal healthy volunteers and three patients with muscle atrophy in the lower extremity were measured in order to select the useful MRI parameters for neuromuscular diagnosis. Since the standard deviation (SD) of both T1 and T2 times in each muscle was found to be within a relatively small range, these values were expected to be useful MRI parameters for neuromuscular diagnosis. On the contrary, rho density was not a valid parameter for diagnosis, as it was demonstrated to have large SDs in the muscles. The differences of these parameters in the three patients also supported the fact that MRI was useful for discriminating between the various types of muscular abnormalities based on relaxation times. The longer T1 and T2 times in women suggested that the content of water in skeletal muscle was higher in women than in men. Moreover, the T1 time in the dominant limbs was found to be shorter than in the non-dominant limbs for rectus femoris only in both men and women, while there were no differences in T2 time in these muscles.