MR Neurography: T1 and T2 Measurements in Acute Peripheral Nerve Traction Injury in Rabbits

Purpose: To prospectively evaluate magnetic resonance ( MR) signal abnormalities and the time course of T1 and T2 values in a rabbit model of acute nerve traction injury with histologic and functional recovery correlation. Materials and Methods: All experimental protocols were approved by the institutional animal use and care committee. Acute traction injury was produced in the sciatic nerve of one hind limb in each of 28 rabbits. The contralateral sham-operated nerves served as controls. Sequential MR imaging and T1 and T2 measurements, as well as measurements of functional changes, were obtained over a 70-day follow-up period, with histologic assessments performed at regular intervals. Signal abnormalities and the time course of T1 and T2 values were observed in the proximal, traction, and distal portions of the injured nerves and the sham-operated nerves, and were compared with each other. Results: Nerves with acute traction injury showed visible hyperintense signals on T2-weighted images and had prolonged T1 and T2 values. Differences of T1 and T2 values were dependent on the sites along the same injured nerve, with the most pronounced and prolonged phase of T1 and T2 increases (peak values of 1333 msec +/- 46 and 79 msec 6 +/- 3.7, respectively) observed in the most severely damaged portion of the injured nerve. T1 and T2 values and functional changes after nerve injury showed a similar time course. A return of T1 and T2 signals to normal values correlated with functional improvement. Conclusion: MR imaging could be used to help predict the degree of nerve damage and monitor the process of nerve recovery in acute peripheral nerve traction injury. (C) RSNA, 2010