Objectives: A dual approach of endoscopic endonasal pituitary surgery with intraoperative MRI
has been advocated as providing increased total resection rates, better visualization
and enhanced illumination. Since the opening of our iMRI suite in May 2017, we report
our experience with a 3T iMRI to assess endoscopic endonasal pituitary adenoma surgery.
Subjects: Between May 2017 and June 2018, twenty-one patients had iMRI-assisted endoscopic
resection of pituitary tumors. They consisted of 16 macroadenomas, 3 giant adenomas
(>4 cm), and 2 functioning microadenomas.
Methods: The authors prospectively reviewed all endoscopic transsphenoidal surgeries performed
in the iMRI suite of their institution. Following endoscopic resection of the pituitary
tumor, iMRI was performed when maximal resection was felt to have been achieved. All
radiological images were independently reviewed by a neuroradiologist, and the histopathology
results were checked and confirmed. If resectable residual tumor was identified, the
patient underwent further resection and iMRI was repeated. A 3T Skyra scanner (SIEMENS)
equipped with a NORAS coil was used for iMRI.
Results: In 14 of the cases, the initial iMRI confirmed the intraoperative assessment: GTR
was obtained in 9, an anticipated unresectable residuum in 3, and suprasellar residual
component requiring craniotomy in 2 giant tumors.
In seven (33%) cases, the iMRI findings prompted an unanticipated return to theater.
Further tumor resection was performed in four (19%), resulting in a GTR in two cases.
In three cases, residual tumor was not found on surgical reexploration.
Permanent DI was noted in 29% of the patients.
Conclusion: Rates of complete adenoma resection improved with the use of iMRI, and tumor volume
reduction improved in cases where the entire tumor could not be resected. There was
an increased rate of postoperative diabetes insipidus and the cases took longer.
Recurrence rates over a longer follow-up period and the cost-effectiveness of this
dual approach are criteria we intend to investigate in the future.
