胸腰椎后路钛合金脊柱内固定系统对术后MRI成像的影响

Influence of posterior thoracic and lumbar titanium internal fixation system on magnetic resonance image

目的：探讨胸腰椎后路钛合金脊柱内固定系统对术后MRI成像的影响。方法：对12例行胸腰椎后路钛合金脊柱内固定的患者术后进行MRI检查，然后对术后钛合金内固定伪影的特点及其对椎管内结构的影响进行分析。结果：钛合金内固定伪影的大小为内固定大小的2～3倍。在矢状面T1和T2加权和轴位T1加权上均可清晰显示脊髓和椎管内的结构。后路系统的连接棒伪影较小，只对紧邻的椎板和小关节处图像辨认有影响，对术后图像观察的影响较小。正确植入的椎弓根螺钉伪影也较大，主要影响对邻近部位椎管侧方、椎间孔、脊神经和后外侧突出的椎间盘等结构的观察。结论：胸腰椎后路脊柱钛合金内固定术后患者进行MRI检查时，应该尽量选择快速自旋回波序列进行扫描，当使用常规自旋回波序列扫描时，应尽量减少回波时间（echo time，TE）。在分析术后MRI图像时，应充分考虑到钛合金内固定伪影对图像的影响，结合患者的临床表现作出正确的判断。

Objective：To discuss the influence of posterior thoracic and lumbar titanium internal fixation system on magnetic resonance image （MRI）. Methods： Twelve patients who received thoracic-lumbar posterior titanium internal fixation system were subjected to MRI scanning. The artifact characteristics of titanium internal fixator and its influence on the spinal canal structure were analyzed. Results.. The artifact size was 2-3 times that of the internal fixator. The details in the spinal canal and spinal cord were clearly displayed on the sagittal T1 and T2 weighted images and axial T1 weighted image. The link rod had small artifact and had influence on the images of adjacent lamina and facet, but had little influence on the observations after operation. The pedicle screw in the right position had considerable artifact, which influenced the images of lateral spinal canal, foramina, nerve root, and posterolateral herniated disc. Conclusion： Turbo spin echo sequence should be chosen for MRI scanning in patients implanted with posterior thoracic and lumbar titanium internal fixation system, with the echo time minimized. When reading the MRI images, the influence of titanium fixation system on the postoperative MRI should be considered in order to obtain the correct information of the patients.