gms | German Medical Science

Objective: The goal of this study was to assess the value of intraoperative high-field MRI (1,5 Tesla) in the treatment of a large cohort of unselected patients with pituitary adenomas undergoing elective surgery via the transsphenoidal approach.

Method: From July 2009 until April 2012, intraoperative MRI (1,5 Tesla, Siemens, Germany) was performed in 110 consecutive patients (63 females, 57 males) with pituitary adenomas operated by transsphenoidal surgery. Age distribution ranged from 9 to 88 years. 65 (59%) of the adenomas were hormone inactive, 45 (41%) revealed hormonal activity. 91 tumors (82,7%) were macroadenomas (>10 mm), 19 (17,3%) microadenomas (<10 mm). All resections were performed microscopically by an experienced (>150 cases) and a very experienced (>500 cases) neurosurgeon. MRI was performed after maximum safe resection was achieved.

Results: In 39 of 110 cases (35,5%) intraoperative MRI suggested remaining tumor tissue. This lead to neuronavigation-guided inspection without further resection in 16 patients (14,6%) and to continuing tumor resection in 23 patients (20,9%). The frequency of further resection depended on the size of the tumors and on endocrine activity. The highest rates were found in large inactive adenomas measuring between 30-39 mm with 5/11 continuing resections (45,5%) and in larger hormone expressing tumors sized 20-29 mm with 3/5 cases (60%). There were no complications related to MR imaging and patient transport to the scanner.

Conclusions: Intraoperative high-field MRI detected possible remaining tumor tissue in more than 30% of patients with pituitary adenomas and led to secondary resections in 20,9% of patients treated by experienced neurosurgeons. IOP MRI is of particular value to improve resection of hormone-active and of large adenomas >30 mm.