Improved reproducibility of dynamic 31P-MRS in the calf muscle during exercise by self-adjusted muscle activity

Dynamic phosphorus MR-spectroscopic ( P-MRS) examinations during muscle exercise allow no n i vasive assessment of changes in the concentrations of phosphocreatine (PCr) and inorganic phosphate (Pi), which are asso ciated with the energy consumption in muscle and may alter in diffe rent pathological conditions. This work describes a low leg ergometer enabling defined loading of human calf muscle d uring spectroscopic measurements with online adjust men of exercise conditions. This set-up was evaluated with rep etitive examinations in a whole-body 3 T MR-scanner du ing isometric load of the calf muscle of two male volunteers. A indicated by variations of ergometer pedal defl ections below 2% and by low variations of the spectroscopic paramete rs (variation of PCr, Pi and pH time courses below 7%), the applied interactive load adjustment provides a high standar diz tion of experiments and, therefore, a high repr oducibility of physiological measurements.