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

Abstract

Dynamic phosphorus MR-spectroscopic (31P-MRS) examinations during muscle exercise allow non invasive assessment of changes in the concentrations of phosphocreatine (PCr) and inorganic phosphate (Pi), which are associated with the energy consumption in muscle and may alter in different pathological conditions. This work describes a low leg ergometer enabling defined loading of human calf muscle during spectroscopic measurements with online adjustment of exercise conditions. This set-up was evaluated with repetitive examinations in a whole-body 3 T MR-scanner during isometric load of the calf muscle of two male volunteers. As indicated by variations of ergometer pedal deflections below 2% and by low variations of the spectroscopic parameters (variation of PCr, Pi and pH time courses below 7%), the applied interactive load adjustment provides a high standardization of experiments and, therefore, a high reproducibility of physiological measurements. © 2012 by Walter de Gruyter Berlin Boston.