Do We Need Intraoperative Magnetic Resonance Imaging in all Endoscopic Endonasal Pituitary Adenoma Surgery Cases? A Retrospective Study

Introduction: Advances in the field of intraoperative imaging, especially intraoperative magnetic resonance imaging (IOMRI), have led to its increasing usage during endoscopic endonasal pituitary surgery (EEPS). Recent studies advocated the usage of this expensive technology. But is it worth to use this technology in every single case?

Methods: Patients with functional or nonfunctional pituitary tumors that were operated via endoscopic endonasal approach (EEA) between June 2017 and May 2019 in the Department of Neurosurgery, Faculty of Medicine, Gazi University, were enrolled. The Institutional Review Board and Ethics Committee approved this retrospective study; oral and written consents of the patients were obtained prior to the study. Also, all patients were informed about the technique and gave their signed consent to IO-MRI during surgery and to the data being used for research purpose. Patients younger than 18 years and patients who did not undergo IO-MRI procedure or not operated via EEA were excluded from the study.

Analysis of the retrospective data was performed using SPSS 21.0 (IBM Corp., Armonk, New York, USA). To compare predictions and to compare residual mass ratios between two Knosp’s grade groups, Fisher’s exact test was used. Variables were preoperative, largest diameter of tumor (<4 cm or ≥4 cm), Knosp’s grade, age, gender, and recurrent surgery.

Results: A total of 200 patients enrolled in the study. In Knosp’s grade 0–2 group, primary surgeon’s opinion and IO-MRI findings were compatible in 150 patients (98.6%). In Knosp’s grade 3–4, correct prediction was performed in 32 (66.6%) patients. When incorrectly predicted, Knosp’s grade 3–4 patients (n = 16) was investigated, in 13 patients, there were still residual tumor in cavernous sinus and in 3 patients there was no residual tumor. Fisher’s exact test showed there is a statistically significant difference of correct prediction between two different Knosp’s grade groups (two-tailed p < 0.0001).

Conclusion: Our results demonstrated IO-MRI is significantly useful in higher Knosp’s grade patients. On the other hand, we do not recommend IO-MRI usage in patients with lower Knosp’s grade adenomas because of increased treatment costs.