Johannes Sarnthein1, Roger Lüchinger2, Marco Piccirelli3, Luca Regli4, Oliver Bozinov4. 1. Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland; University of Zurich, Zurich, Switzerland; Zurich Neuroscience Center, University and ETHZ, Zurich, Switzerland. Electronic address: johannes.sarnthein@usz.ch. 2. Institute for Biomedical Engineering, University and ETHZ, Zurich, Switzerland; University of Zurich, Zurich, Switzerland. 3. Department of Neuroradiology, University Hospital Zurich, Zurich, Switzerland; University of Zurich, Zurich, Switzerland. 4. Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland; University of Zurich, Zurich, Switzerland.
Abstract
BACKGROUND AND OBJECTIVE: 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.
BACKGROUND AND OBJECTIVE: 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.
Authors: Tumul Chowdhury; Frederick A Zeiler; Gyaninder P Singh; Abseret Hailu; Hal Loewen; Bernhard Schaller; Ronald B Cappellani; Michael West Journal: Front Oncol Date: 2018-10-10 Impact factor: 6.244
Authors: Stefanos Voglis; Timothy Müller; Christiaan H B van Niftrik; Lazar Tosic; Marian Christoph Neidert; Luca Regli; Oliver Bozinov Journal: Neurosurg Rev Date: 2020-09-30 Impact factor: 3.042