Suprasellar Anterior-Posterior Diameter Optimizes the Use of Intraoperative MRI in Patients Undergoing Endoscopic Pituitary Surgery

Abstract

Background and objectives: Intraoperative MRI (iMRI) has been demonstrated to improve the extent of resection of pituitary neuroendocrine tumors resected using endoscopic endonasal approaches. We sought to establish if preoperative clinicoradiological parameters could be used to predict which patients are most likely to benefit from iMRI and thus allow more efficient use of this technology.

Methods: A prospectively maintained surgical database of all endoscopic pituitary tumor resections with iMRI guidance performed between May 2017 and September 2023 was accessed. Data were collected on clinical and radiological parameters that may predict reintervention after iMRI. Logistic regression models were constructed to assess the relationship between predictor variables and reintervention after iMRI.

Results: Seventy-three patients were included in the study. After review of the iMRI, 24/73 (33%) patients underwent surgical reintervention. The combined rate of gross total resection/near total resection was 64/73 (88%). The rate of biochemical cure of endocrine disease after surgery for a hormonally active tumor was 15/21 (71%). On univariate logistic regression analysis, the only factor significantly associated with reintervention after iMRI was the suprasellar anterior-posterior diameter (odds ratio 1.1, 95% CI 1.01-1.2, P = .030).

Conclusion: Suprasellar anterior-posterior diameter ≥15 mm predicts the requirement for reintervention after endoscopic resection of pituitary neuroendocrine tumor. Use of this easily obtained radiological parameter will allow iMRI to be used in those patients who are most likely to benefit.

Graphical abstract

FIGURE 1.

Contrast-enhanced sagittal T1-weighted MRI demonstrating a pituitary macroadenoma with suprasellar extension. The suprasellar anterior-posterior diameter (yellow line) is determined by measuring the longest anterior-posterior distance above and parallel to the planum line (green line).

FIGURE 2.

Flow diagram demonstrating the surgical and radiological workflow. After the operating surgeon feels that a maximal safe resection has been achieved, an iMRI is obtained and reviewed by a consultant radiologist. In this series, 24 iMRIs were felt to demonstrate resectable residual tumor. Further tumor was resected in 18/24 cases, but in 6/24 cases, the abnormalities on iMRI were found to be hematoma or hemostatic agents. GTR, gross total resection; iMRI, intraoperative MRI; NTR, near total resection; STR, subtotal resection.

FIGURE 3.

Graphical representation of the basic spline logistic regression model, demonstrating the variation in the probability of reintervention after intraoperative MRI with increasing suprasellar AP diameter. Gray shading indicates 95% CI of the estimate. AP, anterior-posterior.

FIGURE 4.

Receiver-operator characteristic curve demonstrating the performance of the suprasellar AP diameter as a predictor for reintervention after intraoperative MRI. The area under the curve was calculated to be 0.701, and the suprasellar AP diameter was found to significantly outperform a random classifier (P = .008). AUC, area under the curve; AP, anterior-posterior.

FIGURE 5.

Line graph demonstrating the performance of potential cut points in suprasellar AP diameter. A cut point of 15 mm was found to be optimal as assessed by Youden's J statistic. AP, anterior-posterior.

FIGURE 6.

A, Contrast-enhanced sagittal T1-weighted preoperative MRI demonstrating a large PitNET with a suprasellar AP diameter of 31.5 mm. B, T2-weighted intraoperative MRI demonstrating central debulking of the tumor, with a significant suprasellar residual component requiring operative reintervention. C, Contrast-enhanced sagittal T1-weighted preoperative MRI demonstrating a PitNET with suprasellar extension and a suprasellar AP diameter of 11.7 mm. D, T1-weighted intraoperative MRI demonstrating gross total resection. AP, anterior-posterior; PitNET, pituitary neuroendocrine tumor.