Quantitative Volumetric Analysis Post Transsphenoidal Pituitary Adenoma Surgery

Abstract

Pituitary adenomas comprise 10% of all surgically-resected intracranial tumors 1 . The overall age-adjusted incidence is about 0.9/100,000 person-years 2 . These tumors can be resected from a variety of approaches, of which the trans-sphenoidal method is the most common and has the lowest complication rate 3 . There are variations in the trans-sphenoidal approach, mainly differing in the access to the sphenoid sinus or visualization technique used during resection.At our institution, computed tomogram (CT) imaging is used to monitor the progress of pituitary tumors preoperatively. Magnetic resonance imaging (MRI) is used prior to surgical ABSTRACT: Background: Computed tomogram (CT) imaging is often used for immediate postoperative assessment of transsphenoidal pituitary adenoma resection while magnetic resonance imaging (MRI) is used for follow-up. The residual mass is known to decrease in size over time but the difference between the two imaging modalities has not been quantified. Our objective was to quantify the size difference of the residual mass on immediate postoperative CT compared with delayed MRI. Methods: Retrospective analysis of 69 patients who had undergone pituitary adenoma resection at our institution between 2004-2010. Sellar and suprasellar diameter, along with the overall volume of the residual mass were measured on both the immediate postoperative CT and delayed MRI. Results: Average preoperative sellar and suprasellar diameter was 22.2 ± 4.6mm and 20.9 ± 5.9mm, respectively. Average sellar residual diameter on immediate postoperative CT (16.5 ± 5.4 mm, 25% reduction) was significantly larger than delayed MRI (10.6 ± 6.2mm, 52% reduction). The average suprasellar component on CT (15.5± 6.5mm, 26% reduction) was also significantly larger than that on MRI (3.3 ± 5.4 mm, 84% reduction). The postoperative CT showed a 46% reduction in volume while a 71% reduction was noted on the delayed MRI. Conclusion: A significant reduction in residual mass is noted on delayed MR imaging compared with immediate postoperative CT. Therefore, from a resource management and prognostication point of view, CT should be used for immediate postoperative assessment while delayed MRI should be used to assess operative success and for communication with patients.RÉSUMÉ: Analyse volumétrique quantitative après la chirurgie par voie transsphénoïdale pour un adénome pituitaire. Contexte : la tomodensitométrie est souvent utilisée pour l'évaluation du résultat de la résection transsphénoïdale d'un adénome pituitaire immédiatement après la chirurgie alors que l'imagerie par résonance magnétique (IRM) est utilisée pour le suivi de ces patients. On sait que la masse résiduelle de la tumeur diminue avec le temps, mais la différence entre les deux techniques d'imagerie n'a pas été quantifiée. Notre objectif était de quantifier la différence de taille de la masse résiduelle entre la tomodensitométrie effectuée immédiatement après la chirurgie et l'IRM effectuée par la suite. Méthode : Nous avons effectué une analyse rétrospective...

Volumetric assessment of the sella turcica: a re-evaluation

“…MRI grants a better understanding of the patient's anatomy and endocrinological diseases (21). However, it is not always easy to distinguish tumors from hemorrhage and fat packing (13). CT is less expensive, has a broader distribution, better bone assessment, and it is useful in patients where MRI is contraindicated (23).…”

Utility of Early Postoperative High-Resolution Volumetric Magnetic Resonance Imaging After Transsphenoidal Pituitary Tumor Surgery

“…Most studies have recommended a delayed (≥ 2 months), rather than early, postoperative follow-up MRI (6, 7, 10, 13). This stems from the difficulty in interpreting early postoperative images due to persistent cavity enlargement, accumulation of hemorrhagic material, fat packing and other post-operative changes (2, 6, 10, 11).…”

Early postoperative MRI and detection of residual adenoma after transsphenoidal pituitary surgery

“…1,4,11,26 MRI is the standard of care for evaluation of sellar lesions; 6 however, its use in the immediate postoperative period is controversial, with several studies suggesting that early postoperative (EPO) imaging cannot be reliably interpreted. 2,17,18,21,31 As a result, the neurosurgical consensus guidelines for postoperative follow-up after transsphenoidal resection do not recommend EPO MRI. 39 However, studies suggesting that EPO MRI is inaccurate have relied upon outdated MRI methods.…”

“…39 However, studies suggesting that EPO MRI is inaccurate have relied upon outdated MRI methods. 2,17,18,21,31 More recent studies have suggested that EPO MRI is as accurate as late postoperative (LPO) MRI at 3 months. 29,34 However, these studies have failed to compare both imaging tests against an independent gold standard.…”