The Knosp Criteria Revisited: 3-Dimensional Volumetric Analysis as a Predictive Tool for Extent of Resection in Complex Endoscopic Pituitary Surgery

Abstract

BACKGROUND: The Knosp criteria have been the historical standard for predicting cavernous sinus invasion, and therefore extent of surgical resection, of pituitary macroadenomas. Few studies have sought to reappraise the utility of this tool after recent advances in visualization and modeling of tumors in complex endoscopic surgery. OBJECTIVE: To evaluate our proposed alternative method, using 3-dimensional (3D) volumetric imaging, and whether it can better predict extent of resection in nonfunctional pituitary adenomas. METHODS: Patients who underwent endoscopic transsphenoidal resection of pituitary macroadenomas at our institution were reviewed. Information was collected on neurological, endocrine, and visual function. Volumetric segmentation was performed using 3D Slicer software. Relationship of tumor volume, clinical features, and Knosp grade on extent of resection was examined. RESULTS: One hundred forty patients were identified who had transsphenoidal resection of nonfunctional pituitary adenomas. Macroadenomas had a median volume of 6 cm 3 (IQR 3.4-8.7), and 17% had a unilateral Knosp grade of at least 3B. On multiple logistic regression, only smaller log-transformed preoperative tumor volume was independently associated with increased odds of gross total resection (GTR; odds ratio: 0.27, 95% CI: 0.07-0.89, P < .05) when controlling for tumor proliferative status, age, and sex (area under the curve 0.67). The Knosp criteria did not independently predict GTR in this cohort (P > .05, area under the curve 0.46). CONCLUSION: Increasing use of volumetric 3D imaging may better anticipate extent of resection compared with the Knosp grade metric and may have a greater positive predictive value for GTR. More research is needed to validate these findings and implement them using automated methods.

The Predictors of Postoperative Cerebrospinal Fluid Leak in Endoscopic Endonasal Pituitary Surgery: The Role of Tumor Volume

“…Perez Lopez et al found that previous sellar surgery, higher Knosp grade and isointense T2-weighed signal on MRI decreased the chance of gross total resection (GTR) 27 . Tumor volume, not Knosp grade predicted GTR of non-functioning pituitary adenomas in a recent research 28 . Although highlighting the key role of tumor volume rather than the size on GTR, these studies did not focus on the effect of volume on CSF leak.…”

“…27 Tumor volume, not Knosp grade predicted GTR of nonfunctioning pituitary adenomas in a recent research. 28 Although highlighting the key role of tumor volume rather than the size on GTR, these studies did not focus on the effect of volume on CSF leak. In addition, they were performed in mixed patient groups operated via different surgical techniques.…”