[Non invasive investigation of muscle diseases using 31P magnetic resonance spectroscopy: potential in clinical applications].

P-31 MRS has become in a very short time, a major new tool to explore muscle metabolism for clinical diagnostic purposes, while offering a unique non-invasive way to conduct advanced basic research in muscle physiopathology. The comparative analysis of normal and diseased muscle remains a major requirement to further define metabolic events surrounding muscle contraction and the metabolic anomalies underlying pathologies. Also, standardized rest-exercise-recovery protocols for exploration of muscle metabolism by P-31 MRS in healthy volunteers as well as in patients with intolerance to exercise need to be developed. Our protocol is based on a short term intense exercise which is very informative and well accepted by volunteers and patients. Invariant metabolic parameters have been defined to characterize the normal metabolic response to the protocol. Deviations from normality can be directly interpreted in terms of specific pathologies in some favorable cases. In most cases, P-31 MRS provides valuable information which has to be processed in conjunction with traditional invasive biochemical, electrophysiological and histoenzymological tests. For malignant and exercise hyperthermias, P-31 MRS constitutes a diagnostic tool with 100p.cent sensitivity, as compared to contracture tests on muscle biopsies. P-31 MRS has proved particularly useful in the therapeutic follow-up of palliative therapies (coenzyme Q treatment of mitochondriopathies) and in family investigations. It is now an accepted diagnostic tool in the array of tests which are used to characterize muscle disorders in clinical routine. As a research tool, it will keep bringing new information on the physiopathology of muscle diseases in animal models and in humans and should play a role in the metabolic characterization of gene therapy.