Ryan Scott, Moon Andrew S, Gordon Matthew, Flacke Sebastian, Soni Shalin, Salzler Matthew J, Stelma Sarah, Marcantonio Andrew
Department of Orthopaedic Surgery, Tufts Medical Center, Boston, MA.
Department of Radiology, Lahey Hospital & Medical Center, Burlington, MA; and.
J Orthop Trauma. 2021 Jan 1;35(1):e25-e30. doi: 10.1097/BOT.0000000000001848.
To (1) report the thermal changes encountered at the pin/skin interface in a cadaver with a knee-spanning external fixator inside the magnetic resonance imaging (MRI) bore and (2) report on the quality of the MRI sequences collected.
Three commonly used external fixation systems were placed on cadaveric lower extremities to simulate knee external fixation. Fiber optic thermal probes were placed at the pin/skin interface of a femoral and tibial pin. A control probe was embedded in the soft tissues of the thigh. Full knee MRI scans were performed using a 1.5-Tesla magnet. Real-time thermal data were collected. A clinically significant increase in temperature compared with the control was defined as 2°C. Two blinded radiologists evaluated the images for image quality and overall diagnostic utility using a standardized 5-point grading scale.
There were statistically significant differences in the temperature changes between the femoral/tibial pin sites and the control probe sites during each phase of the MRI scan. However, there was only one clinically significant difference in temperature change during a single sequence of one MRI scan of one of the external fixator devices. Overall image quality was graded as a 4 for each image set with 100% interobserver agreement (k = 1.0).
Despite significant differences in temperature changes between the pin sites and controls over multiple MRI sequences in commonly used external fixator devices, the differences in temperature change are likely not clinically relevant. Overall image quality and interpretability of the images were excellent.
（1）报告在磁共振成像（MRI）检查孔内使用跨越膝关节外固定器的尸体中，针/皮肤界面处的热变化情况；（2）报告所采集MRI序列的质量。
将三种常用的外固定系统置于尸体下肢以模拟膝关节外固定。将光纤热探头放置在股骨和胫骨针的针/皮肤界面处。在大腿软组织中植入一个对照探头。使用1.5特斯拉磁体进行全膝关节MRI扫描。收集实时热数据。与对照相比，临床上显著的温度升高定义为2°C。两名盲法放射科医生使用标准化的5分制评分量表对图像的质量和整体诊断效用进行评估。
在MRI扫描的每个阶段，股骨/胫骨针部位与对照探头部位之间的温度变化存在统计学显著差异。然而，在其中一个外固定器装置的一次MRI扫描的单个序列中，温度变化仅有一次具有临床意义。每个图像集的整体图像质量评分为4分，观察者间一致性为100%（k = 1.0）。
尽管在常用外固定器装置的多个MRI序列中，针部位与对照部位之间的温度变化存在显著差异，但温度变化差异可能与临床无关。图像的整体质量和可解释性极佳。
