MAGNETIC-RESONANCE-IMAGING AND P-31 MAGNETIC-RESONANCE SPECTROSCOPY PROVIDE UNIQUE QUANTITATIVE DATA USEFUL IN THE LONGITUDINAL MANAGEMENT OF PATIENTS WITH DERMATOMYOSITIS

Objective. To evaluate the utility of magnetic resonance imaging (MRI) and P-31 magnetic resonance spectroscopy (MRS) in the longitudinal ma nagement of patients with dermatomyositis (DM). Methods. The study gro up consisted of 11 patients, including 3 children, all of whom had a c linical diagnosis of DM. A control group of 8 subjects was studied sim ultaneously. MRI included images as well as calculations of T1 and T2 relaxation times. The P-31 MRS protocol evaluated metabolic status (i. e., inorganic phosphate/phosphocreatine ratios and phosphocreatine and ATP levels) during rest, exercise, and recovery. Results. T2-weighted images of the thigh muscles showed inflammation even when serum creat ine phosphokinase levels were in the normal range. Metabolic abnormali ties, which were accentuated with exercise, were found in 10 patients. In some individuals, bioenergetic defects preceded other changes and persisted after resolution of inflammation. In general, clinical impre ssions correlated with MRI/MRS data. Conclusion. MRI and MRS provide u nique data which are quantitative and which cannot be obtained from ro utine laboratory tests. These MR evaluations appear to be of value in assessing the status of DM patients during treatment with steroids and immunosuppressive drugs.