Pituitary residual tumor detection: incremental value of multimodal assessment

Introduction Postoperative residual tumor is associated with regrowth and recurrence in pituitary adenomas, making maximal safe resection an important therapeutic goal. We evaluated the incremental contribution of microscopy, endoscopic inspection, and 3.0-T intraoperative magnetic resonance imaging (iMRI) to residual tumor detection and assessment of the planned extent of resection. Methods In this retrospective single-center cohort study, 120 consecutive eligible patients undergoing transsphenoidal surgery for pituitary adenoma underwent sequential microsurgical resection, endoscopic inspection, and iMRI. Results Initial endoscopic inspection confirmed the planned extent of resection in 95/120 patients (79.2%) and indicated further resection in 25/120 (20.8%). After any indicated further resection, repeat endoscopic inspection confirmed planned extent of resection achievement before iMRI in all 120 patients. At iMRI, planned extent of resection was judged achieved in 85/120 patients (70.8%), whereas residual tumor was suspected in 35/120 (29.2%) before any iMRI-triggered resection. Among 95 patients considered complete at initial endoscopic inspection, iMRI identified suspected residual tumor in 21 (22.1%). Escalation beyond microscopy was more frequent in recurrent than primary adenomas (12/14, 85.7% vs 34/106, 32.1%; p < 0.001). Each doubling of preoperative tumor volume was associated with higher odds of iMRI-suspected residual tumor (OR 1.79, 95% CI 1.32-2.44; p < 0.001). Discussion Sequential endoscopic inspection and iMRI provided complementary information beyond microsurgical assessment. Additional assessment was more frequently required in recurrent adenomas, while increasing preoperative tumor volume was associated with iMRI-suspected residual tumor. These findings support prospective evaluation of risk-adapted multimodal intraoperative assessment.