Department of Orthopaedic Surgery, Keio University, Shinanomachi 35,Shinjuku-Ku, Tokyo, Japan.
Spine (Phila Pa 1976). 2013 Jan 15;38(2):E66-72. doi: 10.1097/BRS.0b013e31827aacc2.
Basic imaging experiment.
To determine whether in vivo diffusion tensor tractography (DTT) can be used to evaluate the axonal disruption of the chronically compressed spinal cord in tiptoe walking Yoshimura (twy) mice.
In cervical ossification of the posterior longitudinal ligament, axonal disruption results in motor and sensory functional impairment. Twy mice develop spontaneous calcification in the cervical ligaments, which causes chronic compression of the spinal cord. DTT is emerging as a powerful tool for tracing axonal fibers in vivo.
Five twy mice were subjected to DTT at 6, 15, and 20 weeks of age. Magnetic resonance imaging was performed using a 7.0-Tesla magnet (Biospec 70/16; Billerica, MA) with a CryoProbe. Diffusion tensor images were analyzed using TrackVis (Massachusetts General Hospital, MA). Motor performance was evaluated by Rotarod treadmill test and Digigait analysis. Histological analysis was performed by hematoxylin-eosin staining and immunostaining for RT-97 and SMI-31.
High resolution DTT of twy mice in vivo was successful. A lower number of RT-97- or SMI-31-positive fibers were associated with more severe spinal cord compression, which was determined by observing the ligamentous calcification at the C2-C3 level in each twy mouse. The severity of canal stenosis based on magnetic resonance images was strongly correlated with the axial area of the spinal cord. The tract fiber (TF) ratio (the number of TFs at the C2-C3 level/the number of TFs at the C0-C1 level) was strongly correlated with the RT-97/SMI-31-positive area and with motor function (rotarod latency, stride length). Furthermore, a two-part linear regression analysis showed that canal stenosis around 50% to 60% caused a sharp decrease in the TF ratio before the deterioration of motor function.
We conclude that DTT could be useful for detecting the early changes associated with the compressed spinal cord in cervical ossification of the posterior longitudinal ligament.
基础影像学实验。
确定体内扩散张量轨迹（DTT）是否可用于评估踮脚行走 Yoshimura（twy）小鼠慢性受压脊髓的轴突中断。
在后纵韧带骨化症中，轴突中断导致运动和感觉功能障碍。Twy 小鼠的颈椎韧带会自发钙化，导致脊髓慢性受压。DTT 作为一种在体内追踪轴突纤维的强大工具正在兴起。
5 只 twy 小鼠分别在 6、15 和 20 周龄时接受 DTT 检查。磁共振成像（MRI）使用 7.0T 磁体（Biospec 70/16；Billerica，MA）和 CryoProbe 进行。使用 TrackVis（马萨诸塞州总医院，MA）分析扩散张量图像。通过转棒跑步机测试和 Digigait 分析评估运动表现。通过苏木精-伊红染色和 RT-97 和 SMI-31 的免疫染色进行组织学分析。
twy 小鼠体内高分辨率 DTT 成功。RT-97 或 SMI-31 阳性纤维数量较少与脊髓受压更严重相关，这是通过观察每只 twy 小鼠 C2-C3 水平的韧带钙化来确定的。基于 MRI 的椎管狭窄严重程度与脊髓轴径面积强烈相关。束纤维（TF）比（C2-C3 水平的 TF 数量/C0-C1 水平的 TF 数量）与 RT-97/SMI-31 阳性面积和运动功能（转棒潜伏期、步幅长度）强烈相关。此外，两部分线性回归分析表明，在运动功能恶化之前，约 50%至 60%的管腔狭窄导致 TF 比急剧下降。
我们得出结论，DTT 可用于检测颈椎后纵韧带骨化症中受压脊髓的早期变化。
