Magnetic Resonance (MR) Imaging and MR Spectroscopy of Nerve Regeneration and Target Muscle Energy Metabolism in a Model of Prosthesis-Guided Reinnervation in Rats

Rationale and Objectives. We monitored the regeneration of the rat sciatic nerve after its transection and the concomitant alteration in the high-energy phosphates content in the target tibialis anterior muscle. Methods. Rat sciatic nerve was resected and the gap connected with a prosthesis of polytetrafluoroethylene. Progress of reinnervation was monitored by 1 H MR imaging, whereas muscular energy metabolism was evaluated by localized 31 P MR spectroscopy. Results. Reconstitution between the nerve stumps was resumed 8–12 weeks postoperatively. The ratio of phosphocreatine to inorganic phosphate reached a plateau at 46% of the initial level approximately 8 weeks after the operation and recovered thereafter. Immediately after the surgery, muscular pH became slightly alkaline and returned to normal with the progress of reinnervation. Conclusion. Recovery of the muscular energy metabolism began after the reconnection of the severed nerve stumps. The combination of MR imaging and MR spectroscopy followed noninvasively the progress of reinnervation and muscular energy metabolism of the prosthesis-guided nerve regeneration.