Procedure: The MR scan is performed before surgery, and the MR images are transmitted to the neuro-navigation workstation for surgical planning, and then the surgical navigation images and surgical plan are transmitted to the neuro-navigation system in the operating room for navigating the surgery. An intraoperative MR scan is performed when the surgeon believes that the tumor may be completely removed. After the MR coil is fixed to the patient’s head, the magnet is moved into the OR and scanned. If the scan reveals residual tumor, the neuronavigation system data and images are updated, the residual tumor is marked, and the relevant surgical equipment is repositioned before continuing the procedure. Discussion In the 1980s, neuronavigation systems were used in clinical practice to improve surgical accuracy and reduce surgical trauma. Intraoperative MRI systems were first used in neurosurgery in the mid-1990s. Initially, most of them were low-field strength (<0.5T) MRI systems with poor image quality, and in the late 1990s, high-field strength intraoperative MRI systems began to be used in clinical practice. The clinical application of intraoperative MRI, combined with neuronavigation and other technologies, has brought neurosurgery to a new level and reached the height of precision surgery. For transsphenoidal pituitary tumor surgery, it is difficult to objectively evaluate whether the tumor is completely resected, and if there is tumor residual, where is the residual site. The neuronavigation system is now widely used in transsphenoidal pituitary adenoma surgery. The application of the navigation system for transsphenoidal sinus surgery does not require shaving, the reference frame is fixed with a removable harness, which is convenient to use, and the neuronavigation is accurate in positioning, which can help the operator quickly determine the saddle base in cases where the development of the pterygoid sinus is poor or the shape of the pterygoid saddle itself is atypical to determine the saddle base, and can completely replace the C-arm for positioning the saddle base for pituitary microadenoma It can help the surgeon to locate the tumor and guide the surgeon to remove the tumor accurately. However, if only neuronavigation is used to assist surgery, because the preoperative image is applied, when it is used alone for large or huge pituitary adenoma surgery, partial removal of the tumor may cause displacement of the remaining tumor and surrounding normal anatomical structures, and the intraoperative accuracy will be obviously affected. The combination of the two can change the surgical strategy according to the extent of intraoperative tumor resection. For residual tumor, if it is possible to continue resection, the navigation can be updated with the new scanned image to re-mark the residual tumor site and continue resection until a satisfactory result is obtained. If the residual tumor is difficult to continue resection, corresponding adjuvant therapeutic measures, such as gamma knife or drug therapy, can be taken in the early postoperative period according to the type and location of the tumor, while the conventional method requires routine MR examination 3-6 months after surgery to exclude the image interference caused by factors such as filling of hemostatic materials in the operative field in the early postoperative period before determining the residual tumor and starting the next treatment, losing the valuable time for early postoperative treatment. This results in the loss of valuable time for early postoperative treatment. We apply a high field strength intraoperative MRI system with a movable magnet, i.e., only the magnet is moved intraoperatively, which is more practical than intraoperative MRI systems that require moving the patient. For patients whose tumor involves the cavernous sinus but does not completely encircle the internal carotid artery during surgery, we advocate total excision of the tumor as much as possible, but caution should be exercised if the tumor completely encircles the internal carotid artery. In our group, we use three surgical methods: microscope alone, microscope combined with endoscope, and endoscope alone, and the way to adopt depends on the operator's habit and experience. At present, we mostly use the endoscopic approach alone for transsphenoidal surgery, and the endoscopic view is better than that of the microscopic surgery. The majority of the cases in this group were large or giant pituitary adenomas. One of them was a giant pituitary adenoma that invaded the cavernous sinus and completely encircled both internal carotid arteries. In the remaining 30 cases where total resection was planned preoperatively, 12 tumor residues were found in the intraoperative scan after resection, among which 2 cases of cavernous sinus residues were not further resected, and the remaining 10 cases were marked by neuronavigation and continued resection, and 8 cases finally obtained total resection of the tumor, which obviously improved the rate of total resection of the tumor and fully demonstrated the great advantages of combined application of neuronavigation and intraoperative MRI. For trans-pituitary pituitary tumor surgery, the combination of neuronavigation and intraoperative magnetic resonance system has completely changed the traditional surgical mode, greatly improved the accuracy and safety of trans-pituitary pituitary adenoma surgery, and reached the level of precision neurosurgery. The combined use of these techniques should be the future direction of transsphenoidal pituitary adenoma surgery. Operating on large or giant pituitary adenomas through the pterygoid sinus is the advantage of the combined application of neuronavigation and high field strength intraoperative MRI, which will eventually benefit more patients with pituitary adenomas.