Initial Experience with Ultra-Low-Field Intraoperative Magnetic Resonance Imaging in Endoscopic Endonasal Transsphenoidal Surgery for Pituitary Adenoma at Ramathibodi Hospital

Objective: To report our initial experience using ultra-low-field 0.15 Tesla PoleStar N-30 (Medtronic, Louisville, CO, USA) intraoperative magnetic resonance imaging (iMRI) in endoscopic endonasal transsphenoidal surgery (eTSS) for pituitary adenoma (PA) at the Faculty of Medicine Ramathibodi Hospital. Material and Method: From September 2013 to August 2014, information from patients who underwent eTSS for PA with ultra-low-field iMRI was prospectively collected. Data of the scans, at the three point-of-times (before, during and after the eTSS), from the iMRI in these patients were subject to our analysis. Results: A total of the 11 patients successfully underwent eTSS with iMRI during the study period. Two patients were found to have residual PA despite surgeon’s opinion of complete resection of the tumor. Further resection yielded complete removal in one and subtotal removal in the other patient. No serious intra- or postoperative complication occurred in association with iMRI. Conclusion: This is the first report of eTSS for PA with Polestar N-30 iMRI. Our results are similar to those previously published series utilizing earlier versions of, PoleStar N-10 and N-20, ultra-low-field iMRI. These findings, again, confirm the added value of iMRI for the extent of surgical resection in eTSS for PA. Step-by-step illustrations of the iMRI procedure are described. Keywords: Ultra low field, Intraoperative, MRI, Transsphenoidal, Endoscopic, Pituitary, Adenoma