Sarnthein Johannes, Lüchinger Roger, Piccirelli Marco, Regli Luca, Bozinov Oliver
Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland; University of Zurich, Zurich, Switzerland; Zurich Neuroscience Center, University and ETHZ, Zurich, Switzerland.
Institute for Biomedical Engineering, University and ETHZ, Zurich, Switzerland; University of Zurich, Zurich, Switzerland.
World Neurosurg. 2016 Sep;93:168-74. doi: 10.1016/j.wneu.2016.05.097. Epub 2016 Jun 8.
High-field intraoperative magnetic resonance imaging (ioMRI) is becoming increasingly available in neurosurgery centers, where it has to be combined with intraoperative neurophysiologic monitoring (IONM). IONM needle electrodes remain on the patient during ioMRI and may cause image distortions and burns. We tested magnetic resonance (MR) -heating experimentally and investigated the prevalence of complications.
We studied electrodes that are certified for IONM, but not "MR conditional." They consist of copper cables (length, 1.5 m) and needles made of either stainless steel (ferromagnetic) or paramagnetic platinum/iridium alloy. We simulated an ioMRI session with gel and measured the temperature increase with optical fibers. We measured the force that an electrode experiences in the magnetic field. Between 2013 and 2016, we prospectively documented subcutaneous needle electrodes that remained in the patient during intraoperative 3 Tesla ioMRI scans.
The in vitro testing of the electrodes produced a maximum heating (ΔT = 3.9°C) and force of 0.026 N. We placed 1237 subcutaneous needles in 57 surgical procedures with combined IONM and ioMRI, where needles remained in place during ioMRI. One patient suffered a skin burn on the shoulder. All other electrodes had no side effects.
We have corroborated the history of safe use for electrodes with 1.5 m cable in a 3T MRI scanner and demonstrated their use. Nevertheless, heating cannot be excluded, as it depends on location and cable placement. When leaving electrodes in place during ioMRI, risks and benefits have to be carefully evaluated for each patient.
高场强术中磁共振成像（ioMRI）在神经外科中心越来越普及，在这些中心它必须与术中神经生理监测（IONM）相结合。IONM针电极在ioMRI过程中会留在患者身上，可能会导致图像失真和灼伤。我们通过实验测试了磁共振（MR）加热情况，并调查了并发症的发生率。
我们研究了经IONM认证但不具备“MR条件性”的电极。它们由铜电缆（长度为1.5米）和由不锈钢（铁磁性）或顺磁性铂/铱合金制成的针组成。我们用凝胶模拟ioMRI过程，并使用光纤测量温度升高情况。我们测量了电极在磁场中所受的力。在2013年至2016年期间，我们前瞻性地记录了在术中3特斯拉ioMRI扫描期间留在患者体内的皮下针电极情况。
电极的体外测试产生了最大加热温度（ΔT = 3.9°C）和0.026 N的力。我们在57例同时进行IONM和ioMRI的手术中放置了1237根皮下针，这些针在ioMRI期间留在原位。一名患者肩部出现皮肤灼伤。所有其他电极均无副作用。
我们证实了1.5米电缆电极在3T MRI扫描仪中安全使用的历史，并展示了它们的应用。然而，加热不能排除，因为这取决于位置和电缆放置情况。在ioMRI期间将电极留在原位时，必须为每位患者仔细评估风险和益处。
