OBJECTIVE Radiofrequency (RF) tissue heating around deep brain stimulation (DBS) leads is a well-known safety risk during MRI, resulting in strict imaging guidelines and limited allowable protocols. The implanted lead's trajectory and orientation with respect to the MRI electric fields contribute to variations in the magnitude of RF heating across patients. Currently, there are no surgical requirements for implanting the extracranial portion of the DBS lead, resulting in substantial variations in clinical lead trajectories and consequently RF heating. Recent studies have shown that incorporating concentric loops in the extracranial lead trajectory can reduce RF heating. However, optimal positioning of the loops and the quantitative benefit of trajectory modification in terms of added safety margins during MRI remain unknown. In this study, the authors systematically evaluated the characteristics of DBS lead trajectories that minimize RF heating during 3T MRI to develop the best surgical practices for safe access to postoperative MRI, and they present the first surgical implementation of these modified trajectories. METHODS The authors performed experiments to assess the maximum temperature increase of 244 distinct lead trajectories. They investigated the effect of the position, number, and size of the concentric loops on the skull. Experiments were performed in an anthropomorphic phantom implanted with a commercial DBS system, and RF exposure was generated by applying a high specific absorption rate sequence (B1+rms = 2.7 µT). The authors conducted test-retest experiments to assess the reliability of measurements. Additionally, they evaluated the effect of imaging landmarks and perturbations to the DBS device configuration on the efficacy of low-heating trajectories. Finally, two neurosurgeons implanted the recommended modified trajectories in patients, and the authors characterized their RF heating in comparison with unmodified trajectories. RESULTS The maximum temperature increase ranged from 0.09°C to 7.34°C. The authors found that increasing the number of loops and positioning them closer to the surgical burr hole, particularly for the contralateral lead, substantially reduced RF heating. These trajectory modifications were easily incorporated during the surgical procedure and resulted in a threefold reduction in RF heating. CONCLUSIONS Surgically modifying the extracranial portion of the DBS lead trajectory can substantially reduce RF heating during 3T MRI. The authors' results indicate that simple adjustments to the lead's configuration, such as small, concentric loops near the burr hole, can be readily adopted during DBS lead implantation to improve patient safety during MRI.

中文翻译：

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深部脑刺激引线轨迹的手术修改对 3T MRI 期间射频加热的影响：从模型实验到临床实施。

目的 深部脑刺激 (DBS) 引线周围的射频 (RF) 组织加热是 MRI 期间众所周知的安全风险，导致严格的成像指南和有限的允许协议。植入导线相对于 MRI 电场的轨迹和方向会导致患者射频加热强度的变化。目前，植入 DBS 导线的颅外部分不需要手术，导致临床导线轨迹发生很大变化，从而导致射频加热。最近的研究表明，在颅外引线轨迹中加入同心环可以减少射频加热。然而，在 MRI 期间，环路的最佳定位以及轨迹修改在增加安全裕度方面的定量效益仍然未知。在这项研究中，作者系统地评估了 DBS 导联轨迹的特征，这些轨迹可最大限度地减少 3T MRI 期间的射频加热，以开发安全访问术后 MRI 的最佳手术实践，并且他们首次提出了这些修改轨迹的手术实施。方法 作者进行了实验来评估 244 种不同的先导轨迹的最大温度升高。他们研究了同心环的位置、数量和大小对头骨的影响。实验在植入商用 DBS 系统的拟人体模中进行，并通过应用高比吸收率序列 (B1+rms = 2.7 µT) 产生射频暴露。作者进行了重测实验来评估测量的可靠性。此外，他们还评估了成像标志和 DBS 设备配置的扰动对低热轨迹功效的影响。最后，两名神经外科医生将推荐的修改轨迹植入患者体内，作者将其射频加热特征与未修改轨迹进行了比较。结果 最大温升范围为 0.09°C 至 7.34°C。作者发现，增加环路数量并将其放置在更靠近手术钻孔的位置，特别是对于对侧导线，可以大大减少射频加热。这些轨迹修改很容易在外科手术过程中纳入，并使射频加热减少三倍。结论 通过手术修改 DBS 导联轨迹的颅外部分可以显着减少 3T MRI 期间的射频加热。作者的结果表明，在 DBS 导线植入过程中，可以轻松地对导线配置进行简单调整，例如在钻孔附近设置小同心环，以提高 MRI 期间患者的安全性。