Oxidative Phosphorylation in Skeletal Muscle Measured by High-Temporal-Resolution CEST MRI at 3T

Motivation: Oxidative phosphorylation (OXPHOS) in skeletal muscle is of high clinical importance but remains challenging for standard proton MRI. Goal(s): Determine the mitochondrial OXPHOS using High-Temporal-Resolution CEST MRI based Ultrafast Z-Spectroscopy (UFZ) at 3T. Approach: In-magnet plantar flexion exercise (PFE) was performed and changes of amide, phosphocreatine (PCr) and mixed creatine (Cr+) CEST signals were acquired by UFZ. Results: CEST MRI based on UFZ achieves a temporal resolution of 7.2 s for high-resolution Z-spectra. The recovery/decay time constants after pH correction with amideCEST were 85.9 s and 56.3 s for PCr and Cr, respectively. Impact: With temporal resolution comparable to the 31P MRS technique, UFZ MRI shows great potential as a robust tool for non-invasive, localized assessment of mitochondrial function in skeletal muscles, which will assist the diagnosis of related diseases.