Surgical treatment of pituitary adenomas using low-field intraoperative magnetic resonance imaging

Intraoperative magnetic resonance imaging (iMRI) is a new technique for imaging of the brain and is used with increasing frequency during neurosurgical operations, enabling the surgeon to make decisions based on real-time images.

This paper presents the technique for the surgical treatment of pituitary adenomas using low-field iMRI, evaluates the safety of iMRI usage in pituitary surgery and examines the influence of iMRI on the extent of tumor removal.

From October 2008 to December 2010, 18 patients were treated for pituitary adenomas using the low-field iMRI system Polestar N20. The procedures were conducted via the transsphenoidal approach, using the microscopic technique in 15 cases and endoscopically in three cases. The patients' mean age was 56 +/- 15 years; their mean American Society of Anesthesiologists (ASA) score was 2; 67% of them were male. Most of the patients were operated on for macroadenomas, 83% of which were hormonally inactive. The analysis concerned the technical aspects of iMRI usage, such as preparation and surgery time and the quality of the iMRI-scans performed. The safety of iMRI and its influence on decisions regarding further tumor resection.

The operations on pituitary adenomas using iMRI were safe. Only two hemorrhagic complications were noted, and they were not related to iMRI usage. The mean preparation and surgery times were 109 +/- 37 minutes and 238 +/- 188 minutes, respectively. The iMRI images of sella turcica were of satisfactory quality in 16 patients. In 50% of the cases, iMRI conducted when the surgeon believed that the desired extent of tumor resection had been attained showed that there were still tumor remnants to be resected. In 67% of these cases, continued tumor removal lead to achievement of the desired degree of resection.

Low-field iMRI-guided operations on pituitary tumors are safe and feasible, and they ensure an increased radicality of tumor resection.