Neurosurgery. 2026;99(5):1059–1067
A meningioma that yields to suction poses a different operative challenge from one that requires sharp dissection. In this series of 188 resections, tumors with lower T2 signal relative to the middle cerebellar peduncle tended to be firmer at surgery. Measuring this ratio on routine preoperative MRI offers a way to anticipate the demands of internal debulking, particularly when working close to cranial nerves or vessels.
Study and key findings
At one center, a surgeon prospectively graded tumor consistency on a five-point scale during operations performed between 2012 and 2024. For the retrospective imaging analysis, readers blinded to the operative grade sampled three representative 20 mm² regions of tumor, avoiding focal cystic change and calcification. They divided the average tumor signal by the reference signal sampled from the middle cerebellar peduncles.
The mean T2 ratio decreased from 1.98 in soft tumors to 1.71 in intermediate tumors and 1.41 in firm tumors. Diffusion measurements on apparent diffusion coefficient maps showed no significant association with consistency.
Interpretation and limitations
The mean T2 ratio distinguished the soft and firm groups with an area under the ROC curve of 0.868. That comparison excluded the 87 intermediate tumors, nearly half the cohort. For the more practical question of identifying a firm tumor among all patients, a cutoff of 1.515 yielded 75% sensitivity and 75% specificity in the internal test set.
All operations were performed by one skull base surgeon, and only 20 tumors were classified as soft in the study tables. The proposed thresholds need prospective validation at other centers. Whether planning with this measurement improves extent of resection or reduces complications remains untested.
Clinical takeaway
A low tumor-to-peduncle T2 ratio can prompt the team to prepare for mechanical debulking and sharp dissection. Interpret the estimate alongside the tumor’s relationship to adjacent nerves and vessels, and reassess the plan as its consistency and dissection planes become apparent during surgery.