In vivo absolute quantification for mouse muscle metabolites using an inductively coupled synthetic signal injection method and newly developed (1) H/(31) P dual tuned probe.

PURPOSE: To obtain robust estimates of (31) P metabolite content in mouse skeletal muscles using our recently developed MR absolute quantification method and a custom-built (1) H/(31) P dual tuned radiofrequency (RF) coil optimized for mouse leg. MATERIALS AND METHODS: We designed and fabricated a probe consisting of two dual tuned (1) H/(31) P solenoid coils: one leg was inserted to each solenoid. The mouse leg volume coil was incorporated with injector coils for MR absolute quantification. The absolute quantification method uses a synthetic reference signal injection approach and solves several challenges in MR absolute quantification including changes of coil loading and receiver gains. RESULTS: The (1) H/(31) P dual tuned probe was composed of two separate solenoid coils, one for each leg, to increase coil filling factors and signal-to-noise ratio. Each solenoid was equipped with a second coil to allow injection of reference signals. (31) P metabolite concentrations determined for normal mice were well within the expected range reported in the literature. CONCLUSION: We developed an RF probe and an absolute quantification approach adapted for mouse skeletal muscle.