Yamabe Eiko, Nakamura Toshiyasu, Oshio Koichi, Kikuchi Yoshito, Ikegami Hiroyasu, Toyama Yoshiaki
Department of Orthopaedic Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
Radiology. 2008 May;247(2):409-17. doi: 10.1148/radiol.2472070403. Epub 2008 Mar 27.
To prospectively evaluate signal intensity change on T2-weighted magnetic resonance (MR) images and the time course of T2 values and T2 ratios after reinnervation in various nerve injury models in rats.
Institutional animal use and care committee approval was obtained. Thirty male rats made up four groups of rats with an injured left posterior tibial nerve (irreversible neurotmesis, reversible neurotmesis, severe axonotmesis, or moderate axonotmesis) and one control group. There were six rats in each group. Signal intensity changes were seen in the gastrocnemius muscle on the T2-weighted MR images. T2 values were also measured in vivo with the Carr-Purcell-Meiboom-Gill method. Gait function was assessed by calculating the print length factor (PLF). T2 ratios and PLFs on the injured side were compared with those on the unaffected side. Ratios of specific acquisition points within groups were compared by using repeated-measures analysis of variance. Comparisons across the five groups at each acquisition point were performed by using one-way analysis of variance with Scheffe post hoc testing. P < .05 indicated a significant difference.
The more severe the nerve damage, the higher the signal intensity on T2-weighted MR images. There were significant differences in T2 ratios between the nerve injury groups and the control group (P < .05). Changes in T2 values and ratios depended on the degree of nerve injury. In the reversible neurotmesis group, T2 values and ratios began to decrease 28 days after surgery. In the severe and moderate axonotmesis groups, T2 values and ratios began to decrease 14 days after surgery. The starting point of functional recovery also depended on the degree of nerve injury.
The degree and prognosis of nerve injury can be evaluated by observing changes in signal intensity on T2-weighted images and the time course of T2 values and ratios.
前瞻性评估大鼠不同神经损伤模型再支配后T2加权磁共振(MR)图像上的信号强度变化以及T2值和T2比率的时间进程。
获得机构动物使用与护理委员会的批准。30只雄性大鼠分为四组,分别为左侧胫后神经损伤组(不可逆性神经断裂、可逆性神经断裂、重度轴突断裂或中度轴突断裂)和一个对照组。每组6只大鼠。在T2加权MR图像上观察腓肠肌的信号强度变化。还采用Carr-Purcell-Meiboom-Gill方法在体内测量T2值。通过计算印迹长度因子(PLF)评估步态功能。将损伤侧的T2比率和PLF与未受影响侧的进行比较。采用重复测量方差分析比较组内特定采集点的比率。在每个采集点对五组进行比较时,采用单因素方差分析和Scheffe事后检验。P < 0.05表示有显著差异。
神经损伤越严重,T2加权MR图像上的信号强度越高。神经损伤组与对照组之间的T2比率存在显著差异(P < 0.05)。T2值和比率的变化取决于神经损伤的程度。在可逆性神经断裂组中,T2值和比率在术后28天开始下降。在重度和中度轴突断裂组中,T2值和比率在术后14天开始下降。功能恢复的起始点也取决于神经损伤的程度。
通过观察T2加权图像上的信号强度变化以及T2值和比率的时间进程,可以评估神经损伤的程度和预后。