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Imaging Intra-operative Imaging Anaesthetic Concerns for Patients Undergoing Neurosurgical Procedures Utilising Intra-operative Magnetic Resonance Imaging Craig D McClain 1 and Wilson T Chimbira 2 1. Senior Associate in Perioperative Anesthesia, Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children’s Hospital, Boston, Massachusetts and Assistant Professor of Anesthesia, Harvard Medical School, Boston, Massachusetts, US; 2. Assistant Professor of Anesthesiology, Department of Anesthesiology, Mott Children’s Hospital, University of Michigan, Ann Arbor, Michigan, US Abstract Intra-operative magnetic resonance imaging (ioMRI) is an evolving technology that offers precise intra-cranial lesion localisation and intra- operative navigation by combining the high-resolution imaging capabilities of MRI with an operative suite. Developed in the 1990s, ioMRI presents caregivers with a variety of unique challenges revolving around performing surgical procedures in an operating theatre with a high-strength magnetic field. Different types of ioMRI systems exist, differentiated by the relative mobility of the patient and magnet. As with any MRI environment, safety is of paramount concern. Published safety guidelines exist from both the American College of Radiology and the American Society of Anesthesiologists. A variety of checklists can be used to enhance the safety of the ioMRI suite. There are a variety of anaesthetic considerations when caring for patients in this environment including concerns related to the anaesthesia equipment, the patient and the general MRI environment. A multidisciplinary approach can encourage safety and efficiency in this unique operating room. The purpose of this review is to discuss the variety of topics that anaesthesiologists need to consider using this technology, including the indications, specific equipment considerations and unique safety aspects of caring for patients in the ioMRI suite. While performing surgery in a high-strength magnetic field environment carries its own special risks, each type of ioMRI suite presents its own unique challenges to patient safety. Although the challenges are significant, safe care and optimal outcomes are certainly possible with appropriate understanding of the factors unique to the ioMRI environment, good communication, a collaborative approach and proper procedural planning. Keywords Neuroanaesthesia, intra-operative MRI, anaesthesia, image guided neurosurgery, awake craniotomy, MRI safety Disclosure: The authors have no conflicts of interest to declare. Received: 27 September 2013 Accepted: 11 November 2013 Citation: European Neurological Review, 2013;8(2):164–9 Correspondence: Craig D McClain, Boston Children’s Hospital, Department of Anesthesiology, Perioperative and Pain Medicine, 300 Longwood Ave, Bader 3, Boston, MA 02115, US. E: Craig.mcclain@childrens.harvard.edu Modern anaesthetic practice requires the anaesthesiologist to care for extremely sick patients while negotiating the intricacies of myriad procedural environments. One such unique environment that is becoming increasingly important for contemporary anaesthesiologists to be familiar with is that of the intra-operative magnetic resonance imaging (ioMRI) suite. 1,2 ioMRI is an evolving technology that offers precise intra-cranial lesion localisation and intra-operative navigation by combining the high- resolution imaging capabilities of MRI with an operative suite. When ioMRI is combined with other, more conventional, intra-operative navigation strategies, it has the ability to provide increased precision of navigation and aid in resection of a variety of intra-cranial lesions. 3–6 There are a number of important considerations when caring for patients in this environment that are quite different from any other perioperative environment. 7 As these types of operative suites proliferate, it is becoming increasingly important for anaesthesiologists to become familiar with the unique aspects of delivering safe, effective perioperative care for patients undergoing ioMRI-guided neurosurgical procedures. This review will discuss considerations when caring for patients in an ioMRI suite. 164 History ioMRI was developed in the 1990s in an attempt to improve intra- operative navigation and have a real-time assessment of the extent of resection during intra-cranial neurosurgical procedures. 8 Prior to the development of ioMRI, a variety of stereotactic navigational systems had been utilised to improve localisation and precision of resection. These techniques employed either frame-based or frameless systems. All these systems involved triangulating a number of points over multiplanar images of the head acquired preoperatively. The fundamental concern that is common to both types of systems is their reliance on the preoperative imaging. It must be noted that these baseline images occur before positioning for surgery, opening of the craniotomy, loss of blood and cerebrospinal fluid (CSF) and any resection. Thus, the accuracy of these systems can be significantly affected by brain shift, which refers to the intra-operative movement of intra-cranial anatomic structures resulting from a variety of actions including position changes, CSF egress and mass resection. 9 The actual amount of brain shift can vary depending on the tissue type of the lesion, patient positioning, size of craniotomy, CSF loss and volume of tissue resected. 10 Thus, as the surgical procedure goes on, the accuracy © TOUC H ME D IC A L ME D IA 2013