gms | German Medical Science

Objective: This retrospective study evaluates the impact of intraoperative MRI (iMRI) on the extent of transsphenoidal revision surgery in patients presenting with recurrent or persisting non-functioning pituitary adenomas.

Method: Between 2002 and 2012, 109 patients were re-operated at our institution and included in this study. The 1.5 T Magnetom Sonata Maestro Class scanner (Siemens) was used for intraoperative imaging. Control iMRI scans were made if gross total resection (GTR) was supposed or if no further removal seemed possible. For further tumor removal datasets for neuronavigation were updated based on these sequences. The results were evaluated by Fisher's exact test and the paired t test.

Results: Revision surgery was indicated because of tumor persistence in 26 (23%), and regrowth in 85 (77%) patients. Seventy two (65%) patients were operated by a single procedure. Combinations of transsphenoidal and transcranial approaches were used in 26 (67%) patients. Histological analysis showed gonadotrope adenoma (n=68; 61%), null cell adenoma (n=31; 28%) and corticotrope adenoma (n=8; 7%). Preoperative hypopituitarism was detected in 67 (60%), and visual compromise in 36 (33%) patients. On the first intraoperative control scan, GTR was confirmed in 19 (17%) patients. The remnants were located as follows: cavernous sinus, n=65 (71%); suprasellar space, n=35 (38%); retrosellar space, n=9 (10%). Additional resection was possible in 62 (67%) patients. The volume reduction thus made possible by iMRI was significant (p<0.0001). The final GTR rate was 49%, which was significantly higher than on the first iMRI scans (p<0.0001). Invasive tumors were less likely to be totally resected (p<0.0001; RR=7.5, 95% CI 2.9-19.1), while tumor volume <10 cm³ did not correlate with a higher GTR rate. Improvement of vision was seen in 29 (86%) patients. Ten (15%) patients showed recovery of pituitary function, while 11 (12%) patients postoperatively suffered from impaired pituitary axes. Another surgical procedure due to tumor remnants was indicated in 7(6%) patients. In 29 (27%) patients remnants were treated by radiotherapy. None of the patients with GTR suffered from tumor recurrence during follow-up of 3.8±2.4 years.

Conclusions: The use of iMRI in transsphenoidal reoperations for non-functioning pituitary adenomas leads to significantly higher GTR rates. It thus prevents additional operations and reduces the number of unexpected remnants.