Volumetric mapping of the intracellular magnesium ion concentration in human calf muscles using 31P MRSI at 7 Tesla

Intracellular free magnesium ion concentration [Mg²⁺_free] is an important parameter in the regulation of the energy metabolism and can be assessed non-invasively by the use of ³¹P MRSI. The purpose of this study is to show that volumetric mapping of [Mg²⁺_free] in the human calf muscle is possible at B₀=7T with a voxel size of 1 ml. The [Mg²⁺_free] maps of healthy volunteers showed local differences, presumably resulting from different muscle fiber compositions. Two different approaches employed for the calculation of [Mg²⁺_free] yielded comparable maps but different absolute values, indicating the need for further investigation.