Magnetic Resonance (MR) compatible ergometers are specialized ergometers used inside the MR scanners for the characterization of tissue metabolism changes during physical stress. They are most commonly used for dynamic phosphorous magnetic resonance spectroscopy (31P MRS), but can also be used for lactate production measurements, perfusion studies using arterial spin labelling or muscle oxygenation measurements by blood oxygen dependent contrast sequences. We will primarily discuss the importance of ergometers in the context of dynamic 31P MRS. Dynamic 31P MRS can monitor muscle fatigue and energy reserve during muscle contractions as well as the dynamics of recuperation of skeletal muscle tissue during the following recovery through signal changes of phosphocreatine (PCr), inorganic phosphate and adenosine triphosphate (ATP). Based on the measured data it is possible to calculate intracellular pH, metabolic flux of ATP through creatine-kinase reaction, anaerobic glycolysis and oxidative phosphorylation and other metabolic parameters as mitochondrial capacity. This review primarily focuses on describing various technical designs of MR compatible ergometers for dynamic 31P MRS that must be constructed with respect to the presence of magnetic field. It is also expected that the construction of ergometers will be easy for the handling and well accepted by examined subjects.

Christian Doppler Laboratory for Clinical Molecular MR Imaging Vienna Austria

Institute for Clinical and Experimental Medicine Department of Diagnostic and Interventional Radiology MR unit Prague Czech Republic

Medical University of Vienna Department of Internal Medicine 3 and High Field MR Centre Division of Endocrinology and Metabolism Department of Biomedical Imaging and Image guided Therapy Vienna Austria

Slovak Academy of Sciences Institute of Measurement Science Department of Imaging Methods Bratislava Slovakia

University of Oxford RDM Cardiovascular Medicine Oxford Centre for Clinical MR Research Oxford United Kingdom

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