P-31-MR SPECTROSCOPY OF THE SKELETAL-MUSC LES UNDER LOAD - DEMONSTRATION OF NORMAL ENERGY-METABOLISM COMPARED TO DIFFERENT NEUROMUSCULAR DISEASES

Purpose: P-31-MR spectroscopy of skeletal muscle under exercise was us ed to obtain the range of normal variation and comparison was made for different neuromuscular diseases. Methods: 41 examinations of 24 volu nteers and 41 investigations in 35 patients were performed on 1.5T MR systems (Gyroscan S15 und S15/ACSII, Philips). Localised P-31-MR spect ra of the calf muscle were obtained in time series with a resolution o f 12 s. Results: Two types of muscle energy metabolism were identified from the pattern of spectroscopic time course in volunteers: While th e first group was characterised by a remarkable decline to lower pH va lues during exercise, the second group showed only small pH shifts (mi nimum pH: 6.48 +/- 0.13 vs 6.87 +/- 0.07, p<10(-6)) although comparabl e workload conditions were maintained. The PH-values correlated well w ith blood lactate analysis. Patients with metabolic disorders and chro nic fatigue syndrome (CFS) showed decreased resting values of PCr/(PCr +P-i) and increased pH levels during exercise. PCr recovery was signif icantly delayed (0.31 vs 0.65 min(-1), p < 0.00005) in metabolic muscl e disorders but was normal in CFS patients. Conclusion: Findings in vo lunteers indicate utilisation of different metabolic pathways which se ems to be related to the fibre type composition of muscle. Reduced res ting levels for PCr/(PCr+P-i), altered pH time courses, and decreased PCr recovery seem to be helpful indicators for diagnosis of metabolic muscle disorders.