Original ArticleThe Value of Intraoperative Magnetic Resonance Imaging in Endoscopic and Microsurgical Transsphenoidal Pituitary Adenoma Resection
Introduction
Selective microsurgical transsphenoidal adenomectomy was the main operative technique for decades. The endoscopic technique has become a common alternative after its introduction and further development in transnasal transsphenoidal skull base surgery.1, 2 Improved visualization of the sella and less trauma to the nasal mucosa are potential benefits of this approach.2 Furthermore, the endoscopic approach seems to be superior for invasive pituitary tumors.3
Our previously published data show that the routine use of intraoperative magnetic resonance imaging (iMRI) increases the extent of resection (EoR) and decreases the residual volume of pituitary adenomas.4 Sylvester et al.5 reported longer progression-free survival (PFS) in patients with gross total resection (GTR) of pituitary adenomas. Furthermore, complementarity and benefit of a combined approach with iMRI and endoscopy has been reported.5
In this study, we evaluated the influence of surgical technique and additional use of iMRI on EoR and residual tumor volume in iMRI and postoperative magnetic resonance imaging (MRI) in transnasal transsphenoidal pituitary surgery. In addition, we have evaluated pituitary function, postoperative tumor volume, and surgical complications.
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Patients and Follow-Up Assessment
Patients operated on for pituitary adenoma between 2009 and 2016 were assessed retrospectively. An endoscopic transsphenoidal approach has been performed at our department since 2015 by 2 neurosurgeons without previous experience with the endoscopic technique. Since then, elective patients with pituitary adenoma have been treated with this approach. A historic cohort of 68 consecutive patients treated microsurgically were used for evaluation. The transsphenoidal microsurgical adenomectomy was
Patient Characteristics
A total of 96 patients treated with pituitary adenoma were assessed. A mean age of 54 years (range, 7–78 years) was noted. Males were mostly treated (74%, n = 71). The demographic data are summarized in Table 1.
Tumor Characteristics and Surgical Procedure
The most common histologic subtype was nonfunctioning adenoma (n = 65, 67.7%) followed by GH-secreting (n = 16, 16.7%) and adrenocorticotropic hormone (ACTH)-secreting adenoma (n = 10, 10.4%; Table 1). Forty-nine patients (51%) were graded according to Knosp classification as 0–2 (34
Discussion
The main aim of our study was to analyze the influence of surgical technique on the EoR before iMRI and to evaluate the extent of additional resection after iMRI. According to our results, iMRI shows significantly more often resectable tumor remnants after microsurgical than after endoscopic approach. This effect is even more pronounced in less invasive pituitary adenomas (Knosp grade 0–2). Moreover, the tumor remnant volume in iMRI is significantly higher with the microsurgical technique. A
Conclusions
iMRI seems to level the playing field between endoscopic and microsurgical resection of pituitary adenomas by identifying hidden tumor remnants. These remnants can be identified and targeted by the surgeon, leading to similar rates of GTR and EoR using either technique. The microsurgical approach with limited visualization of the surgical site benefits disproportionately. The relative benefit of iMRI appears to be smaller with an endoscopic approach and tumors graded Knosp grade 0–2. Using
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.