Integration of Early Postoperative MRI Increases Diagnostic Confidence and Concordance for Detection of Residual Tumor after Transsphenoidal Pituitary Surgery

Purpose: Controversy exists over the utility of early postoperative MRI after transsphenoidal resection for pituitary lesions. The purpose of this study was to determine whether inclusion of early postoperative MRI increases the diagnostic confidence in detection of residual tumor after transsphenoidal resection.

Methods: A total of 109 consecutive patients who underwent transsphenoidal resection of a pituitary lesion between January 1, 2013, and December 31, 2014, and had an early MRI were included. Patients were imaged at <2 days (early postoperative MRI), 3 months, and then yearly for at least four years. Two fellowship-trained neuroradiologists blinded to all clinical data assessed all 3-month postoperative imaging first without viewing any early postoperative imaging. The same radiologists reassessed all cases 2 weeks later, interpreting the 3-month postoperative scan with comparison to the early postoperative MRI. A four-point scoring system was created to assess diagnostic confidence for residual lesion: (1) poor level (2) low level (3) moderate level and (4) high level of confidence. Inter-reader reproducibility for presence or absence of residual lesion was compared for interpretations with and without reference to early postoperative images utilizing Cohen’s kappa coefficient.

Results: Confidence scores for the presence or absence of residual lesion on the three-month scan increased for both readers when given the ability to reference early postoperative images compared with interpretation without early postoperative images available (reader 1: 2.72 vs. 2.50, p = 0.048, reader 2: 3.92 vs. 3.62, p = 0.0001). The inter-reader agreement for the presence or absence of residual lesion was also higher with the inclusion of early postoperative imaging compared with interpretation of the three-month scan alone (kappa =0.67 and 0.62, respectively, p = 0.01)

Conclusion: An immediate postoperative MRI can be a valuable tool to increase the radiologist’s diagnostic confidence in identifying residual pituitary lesions and increases reader concordance.