DYNAMIC P-31 MAGNETIC-RESONANCE SPECTROSCOPY IN ARTERIAL OCCLUSIVE DISEASE - EFFECTS OF VASCULAR THERAPY ON SPECTROSCOPIC RESULTS

RATIONALE AND OBJECTIVES. The aim of the authors' prospective study wa s to explore therapy-induced changes of muscular metabolism in arteria l occlusive disease (AOD). MATERIALS. Before and after vascular therap y, respectively, 31 patients with AOD were examined by dynamic phospho rus-31 (P-31) magnetic resonance spectroscopy (MRS) at 1.5 T; in the m agnet, the quadriceps muscle was stressed by an isometric and an isoto nic form of exercise until exhaustion, respectively. Twenty-three pati ents were treated by standardized percutaneous transluminal angioplast y; eight patients underwent a vascular operation. RESULTS. Vascular th erapy induced a marked improvement of clinical and angiographic result s. At the same work load, exercise-induced metabolic changes of the qu adriceps muscle were significantly less pronounced after the vascular therapy: maxima of the ratio inorganic phosphate (Pi)/phosphocreatine (PCr) (isometric exercise: 0.34 [after therapy] versus 0.44 [before th erapy]; isotonic exercise: 0.36 [after therapy] versus 0.51 [before th erapy]) as well as minima of pH (isometric exercise: 7.00 [after thera py] versus 6.93 [before therapy]; isotonic exercise: 7.00 [after thera py] versus 6.93 [before therapy]). In relation to maximal values of Pi /PCr, the extent of acidosis was smaller after vascular therapy, resul ting in a flatter slope of the regression line between these parameter s (b = -0.24 +/- 0.10 versus b = -0.31 +/- 0.09). After both of the ex ercises, time of half recovery of Pi/PCr was significantly shorter aft er vascular therapy (isometric exercise: 43 seconds [after therapy] ve rsus 83 seconds [before therapy]; isotonic exercise: 42 seconds [after therapy] versus 57 seconds [before therapy]). CONCLUSIONS. After effe ctive vascular therapy, minor exercise-induced metabolic changes (incr eased ''work/energy cost-index''), a decreased contribution of anaerob ic glycolysis to total adenosine triphosphate production as well as a markedly increased recovery rate of Pi/PCr are unequivocal spectroscop ic proofs of an improved oxidative metabolism of muscle cells because of increased tissue perfusion.