CEST-pHou

In this proposal, the main objective is to optimize Chemical Exchange Saturation Transfer (CEST) magnetic resonance imaging (MRI) for pH mapping on a 3-T clinical scanner in skeletal leg muscle of patients with neuromuscular disorders. Using MR spectroscopy (MRS), we have shown the interest of assessing pH in skeletal muscle of patients with various myopathies. We hypothesize that, expanding the use of pH as a biomarker to pH mapping at high spatial and temporal resolution, might render it a valuable outcome measure in the evaluation of disease progression in patients suffering from neuromuscular disorders. Exchangeable solute protons can be the creatine (Cr) and PCr amine or the amide protons, all of which can be used for determining pH. PCr and Cr are metabolites that are abundant in skeletal muscle, playing a crucial role in energy metabolism. The first main objectif is to compare the proposed Cr-PCr CEST MRI approach to the established APT methodology for pH mapping. The most reproducible and sensitive methodology will be selected for further use. The interleaved 1H/31P CSI sequence will be used as the ‘gold standard’ MRS approach. The second main objectif is to accelerate the CEST MRI data processing and acquisition, using artificial intelligence (convolutional neural network). If successful, this will lead to significantly shorter acquisition times for CEST MRI. A fast CEST MRI acquisition will leave the opportunity to obtain other important MRI/S biomarkers without increasing the burden of long acquisition times in patients.