Prevalence of Complications in Intraoperative Magnetic Resonance Imaging Combined with Neurophysiologic Monitoring

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• 作者：Johannes Sarnthein¹ ; ⁴ ; ⁵ ; ^{johannes.sarnthein@usz.ch" class="auth_mail" title="E-mail the corresponding author} ; Roger Lü ; chinger² ; ⁴ ; Marco Piccirelli³ ; ⁴ ; Luca Regli¹ ; ⁴ ; Oliver Bozinov¹ ; ⁴
• 关键词：Diamagnetic metal ; Electrode cable length ; Ferromagnetic metal ; Intraoperative MRI ; Intraoperative neurophysiologic monitoring ; Magnetic force ; Paramagnetic metal ; RF heating
• 刊名：World Neurosurgery
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：93
• 期：Complete
• 页码：168-174
• 全文大小：2060 K

文摘

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.

Methods

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.

Results

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.

Conclusions

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.