A Retrospective cohort study of Knosp grade reporting of cavernous sinus invasion in pituitary macroadenomas

PURPOSE: The Knosp grading system classifies the extent of cavernous sinus invasion (CSI) in pituitary adenomas (PAs). Knosp grade is predictive of surgical remission rates and is used in decision-making for the management of these adenomas. This study evaluates the rate and accuracy of Knosp grade reporting of PAs by radiologists. METHODS: This is a retrospective observational study of 100 consecutive patients with pituitary macroadenomas who underwent pituitary MR imaging between March 2023 and March 2025. The rate of CSI reporting in radiologist reports of the scans was determined, and the reported grade was compared with the Knosp grade calculated by the study panel. RESULTS: Radiologist reports contained a specific comment regarding CSI, or its absence, in 73/100 (73%) of patients. Analysing left and right cavernous sinuses as separate observations, implicit phrasing reporting a specific Knosp grade occurred in 12/200 (6%), and explicit reporting occurred in 10/200 (5%). Analysis of implicit and explicit reporting revealed a statistically significant difference between the reported Knosp grades and study grades (p = 0.02). No significant correlation was found between CSI reporting rates and patients undergoing surgery (p = 0.179), radiotherapy (p = 0.427), or medical therapy (p = 0.127) before or at the time of the MRI. CONCLUSION: Despite the integral importance of CSI in pituitary adenoma management decisions as enshrined in international guidelines, the rate and accuracy of Knosp grade reporting are suboptimal. Knosp reporting in MRI reports should be standardised to improve the rate and quality of CSI reporting.