**1. Introduction**

In 1991 at the Brigham and Women's hospital first intraoperative MRI (ioMRI) was used. Since then, its use and techniques have evolved. It is the most accurate imaging in intraoperative setting as it provides the real time information of tumor residue and guides further resections even if anatomy is distorted by brain shift [1]. The extent of resection is a prognostic factor in most tumor surgeries, like surgery for gliomas. These patients will benefit from ioMRI. The role of ioMRI is not only restricted to gliomas but other tumors/procedures as well. Designated operation theaters, operative instruments and MRI-compatible monitoring devices were required for ioMRI which has made this an expensive modality, with only few centers in the world able to afford such a facility. In this chapter we will discuss about types of ioMRI, anesthesia considerations and its role in different types of neurosurgical procedures.
