Testing magnetic resonance imaging parameters to predict pituitary macroadenoma consistency

Pituitary macroadenomas (PMAs) are frequently encountered tumors, predominantly characterized as soft and easily resectable during neurosurgery. In contrast, fibrous PMAs present difficulties during surgical removal. Therefore, the ability to predict the consistency of PMAs preoperatively could enhance surgical planning.To evaluate the ability of conventional T2-weighted imaging (T2WI) to predict PMA consistency by comparing isolated tumor signal intensity with the adenoma-to-middle cerebellar peduncle (ACP) ratio.Magnetic resonance imaging (MRI) scans from 45 patients with PMAs were independently reviewed by 3 blinded radiologists. For each case, the signal intensity (SI) of the adenoma and of the middle cerebellar peduncle was measured, and the ACP ratio (SI_adenoma/SI_peduncle) was calculated. Tumor consistency (soft or fibrous) was determined intraoperatively by a single neurosurgeon.Intraoperative assessment classified 29 PMAs (64.4%) as soft and 16 (35.6%) as fibrous. Isolated adenoma SI on T2WI differed significantly between soft and fibrous tumors (p = 0.013), while the ACP ratio demonstrated stronger discriminatory power (p < 0.0001). The receiver operating characteristic (ROC) curve yielded an area under the curve of 0.939 for the ACP ratio. Threshold values > 1.59 were highly predictive of soft tumors (sensitivity 72.4%; specificity 100.0%), whereas values < 1.27 were associated with fibrous tumors (sensitivity 100.0%; specificity 37.5%).Although isolated adenoma SI on T2WI showed statistical significance, it was not sufficient for consistent preoperative prediction of tumor consistency. The ACP ratio provided superior accuracy and clinical utility, supporting its role as a noninvasive imaging biomarker to enhance preoperative assessment and surgical planning in patients with pituitary macroadenomas.