Fig. 1.

Flow chart of the data acquisition, image reconstruction and quantification processes for measuring PCr concentration in muscles of the lower leg. Inorganic phosphate phantoms are used to derive a calibration curve of PCr concentration as a function of signal intensity (top). Imaging of phantomes is performed under fully relaxed conditions (TR = 60 s), and therefore there is no T₁ correction step in the processing. In-vivo PCr images (bottom) are corrected (B₁, T₁) and compared voxelwise against the calibration curve. In cases where significant fat infiltration is present in the muscles, ¹H images can be used to estimate the fraction of fat/muscle in the tissue.