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Lower extremity skeletal muscle of 22 individuals (five normal volunteers and 17 patients with muscular or neuromuscular diseases) was studied with magnetic resonance imaging. Axial images generated with spin-echo pulse sequences using short repetition times (500-900 msec TR) and short echo times (30-60 msec TE) provided excellent contrast between fat (high signal intensity) and muscle (intermediate signal intensity). Seventeen patients with clinically verified muscle disorders were evaluated in a manner similar to the normal volunteers. Conditions studied include Duchenne muscular dystrophy (three patients), limb-girdle muscular dystrophy (five), facioscapulohumeral dystrophy (three), and spinal muscular atrophy, amyotrophic lateral sclerosis, hereditary sensorimotor neuropathy, cerebral palsy, poliomyelitis, and Kearn-Sayre mitochondrial muscle disease (one each). General patterns of muscle abnormality were common among the diseases and included decreased or increased muscle size and a spectrum of muscle replacement by fat. Variable patterns were observed within disease groups and for each patient. Much phosphorus-31 spectroscopy has been performed in a blind fashion with no proton map of normal/abnormal muscle distribution to guide the spectroscopist. This study emphasizes the worth of having a muscle proton map of patients with muscle dysfunction to assure that meaningful phosphorus spectroscopic information is obtained from a volume of tissue limited to an appropriate muscle.
Murphy et al. (Sat,) studied this question.