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High-field magnetic resonance imaging (MRI) (1.5 T) has recently been introduced into the neurosurgical operating room for intraoperative resection control and functional neuronavigational guidance. However, long-lasting neurosurgical procedures in an operating room equipped with a high-field MRI scanner raise new challenges to the anesthesiologist. In particular, monitoring of vital signs during anesthesia requires equipment compatible with working in close vicinity to the strong magnetic field. However, even MRI-compatible electrocardiographic (ECG) monitoring interferes with electromagnetic fields, so several ECG artifacts can be observed in static and pulsed magnetic fields. As shown in this study, pulsed high-frequency fields induce characteristic field frequency-based artifacts in the ECG that can imitate malignant arrhythmia or provoke ST-segment abnormalities. The knowledge of possible and characteristic ECG artifacts during high-field MRI is therefore essential to prevent misinterpretation. Moreover, interference-free parameters such as pulse oximetry or invasive blood pressure curves are highly relevant during intraoperative MRI scans.

Intraoperative magnetic resonance imaging (MRI) has been used for years to update neuronavigation and for intraoperative resection control. For this purpose, low-field (0.1-0.2 T) MR scanners have been installed in the operating room, which, in contrast to machines using higher magnetic field strength, allowed the use of standard anesthetic and surgical equipment. However, these low-field MR systems provided only minor image quality and a limited battery of MR sequences, excluding functional MRI, diffusion-weighted MRI, or MR angiography and spectroscopy. Based on these advantages, a concept using high-field MRI (1.5 T) with intraoperative functional neuronavigational guidance has been developed that required adaptation of the anesthetic regimen to working in the close vicinity to the strong magnetic field. In this paper the authors present their experience with the first 80 consecutive patients who received anesthesia in a specially designed radio frequency-shielded operating room equipped with a high-field (1.5 T) MR scanner. We describe the MR-compatible anesthesia equipment used including ventilator, monitoring, and syringe pumps, which allow standard neuroanesthesia in this new and challenging environment. This equipment provides the use of total intravenous anesthesia with propofol and remifentanil allowing rapid extubation and neurologic examination following surgery. In addition, extended intraoperative monitoring including EEG monitoring required for intracranial surgery is possible. Moreover, problems and dangers related to the effects of the strong magnetic field are discussed.