DISCUSSION:
IMRI during transsphenoidal resection of pituitary tumors has the capacity to maximize outcomes in a busy community hospital setting. Our data shows that gross total resection was achieved and determined during surgery in the majority of our patients (67% compared to 33%). This shows that iMRI provides an advantage to help determine gross total resection of a pituitary mass during a case in real time. This has the potential to allow for maximal and safe complete removal of tumor bulk during transsphenoidal resection in addition to limiting overly aggressive resection in anatomically hazardous locations. The use of iMRI allowed our team to not only achieve maximum tumor resection, it also allowed the team to visualize decompression of vital nearby neurovascular structures that pituitary tumors usually adhere to. For example, decompression was able to be visualized in and around the cavernous sinus, carotid arteries, and optic apparatus.
Our study also shows that iMRI can be used typically only one time during a case. The frequency of iMRI use for our study was only one time during most cases and this allowed our team to be efficient with achieving the best results for our patients. IMRI was typically used once during two key phases of the operation. It was used to identify intraoperative residual tumor location or to confirm gross total resection before closing. Using iMRI multiple times during a case is a rare occurrence. Using iMRI only one time during a case can help to avoid excessive increase to the usual operative timing for a surgeon and increases in personnel needed for managing the iMRi.
We also found that there was a significant difference in the evidence of post-operative tumor residual detected. Our study demonstrates that the use of iMRI to achieve gross total resection in real time has the ability to decrease the presence of residual tumor postoperatively in patients. Our study found that there may be an enough positive correlation between these two measures as residual tumor was found in less patients post-operatively (32% compared to 68%). The reason for residual tumor being seen post-operatively in 32% of our patients may hinge on the variety of presentations and extent of tumor involvement especially in unresectable high risk regions. In these cases it is our impression that iMRI facilitates the decision to cease excessive manipulation thereby improving safety and possibly decreasing time spent during surgery in specific cases.