Effect of Peripheral Nerve Injury on Nuclear Magnetic Resonance Relaxation Times of Rat Skeletal Muscle

RATIONALE AND OBJECTIVES The authors evaluate the changes in magnetic resonance (MR) relaxation times of rat skeletal muscles in vivo after nerve injury and during neural recovery, and determine the major determinants of relaxation times. MATERIALS Magnetic resonance relaxation times, blood volume, and water and fat content were examined after nerve injury and during recovery with time course. RESULTS Nerve injury led to longer T2 values compared with controls, but there were no significant changes in T1 values. After the initial prolongation of T2 after nerve injury, no changes were observed. Neural recovery resulted in a return of T2 values to normal. The time course of changes in blood volume was similar to that of changes in T2, and T2 values were correlated strongly with 19-fluorine-MR spectroscopy estimates of blood volume (r2 = 0.94). CONCLUSIONS T2 values may be useful to monitor recovery after nerve injury and may be related to the blood volume in skeletal muscle.