Intraoperative magnetic resonance imaging for neurosurgical procedures: anesthetic implications

Intraoperative magnetic resonance imaging (IMRI) for tumor resection allows a neurosurgeon to pinpoint the exact location of the tumor before resection and to navigate to the tumor after the incision is made. Although the anesthetic management is not substantially different from that for other neurosurgical procedures, strategies to keep the patient and operating room personnel safe can be challenging. Because of the risk of injury by the strong force of the magnet, safety precautions with respect to anesthetic delivery must be taken. Ferrous objects must be removed and kept outside the operating room. Only MRI-compatible equipment is allowed in the MRI operating room. This includes the anesthesia machine, anesthesia cart, intubating equipment, monitors, stethoscopes, poles for intravenous solutions, and body warmers. Surgical equipment and instruments must be MRI-compatible. Absolute contraindications to entering the MRI suite include pacemakers, cochlear implants, certain cranial aneurysm clips, and metal joints or implants. Goals of anesthesia delivery during IMRI procedures include the following: (1) promoting the safety of patients and staff, (2) preventing MRI-associated accidents, (3) identifying potential equipment-related hazards, (4) recognizing limitations of physiologic monitoring, and (5) acknowledging other potential hazards such as noise.