title: Intraoperative high-field MRI for transsphenoidal reoperations of nonfunctioning pituitary adenoma.
abstract: OBJECTIVE
  The loss of anatomical landmarks, frequently invasive tumor growth, and tissue changes make transsphenoidal reoperation of nonfunctioning pituitary adenomas (NFAs) challenging. The use of intraoperative MRI (iMRI) may lead to improved results. The goal of this retrospective study was to evaluate the impact of iMRI on transsphenoidal reoperations for NFA.
  
  
  METHODS
  Between September 2002 and July 2012, 109 patients underwent reoperations in which 111 transsphenoidal procedures were performed and are represented in this study. A 1.5-T Magnetom Sonata Maestro Class scanner (Siemens) was used for iMRI. Follow-up iMRI scans were acquired if gross-total resection (GTR) was suspected or if no further removal seemed possible.
  
  
  RESULTS
  Surgery was performed for tumor persistence and regrowth in 26 (23%) and 85 (77%) patients, respectively. On the initial iMRI scans, GTR was confirmed in 19 (17%) patients. Remnants were located as follows: 65 in the cavernous sinus (71%), 35 in the suprasellar space (38%), 9 in the retrosellar space (10%). Additional resection was possible in 62 (67%) patients, resulting in a significant volume reduction and increased GTR rate (49%). The GTR rates of invasive tumors on initial iMRI and postoperative MRI (poMRI) were 7% and 25%, respectively. Additional remnant resection was possible in 64% of the patients. Noninvasive tumors were shown to be totally resected on the initial iMRI in 31% of cases. After additional resection for 69% of the procedures, the GTR rate on poMRI was 75%. Transcranial surgery to resect tumor remnants was indicated in 5 (5%), and radiotherapy was performed in 29 (27%) patients. After GTR, no recurrence was detected during a mean follow-up of 2.2 ± 2.1 years.
  
  
  CONCLUSIONS
  The use of iMRI in transsphenoidal reoperations for NFA leads to significantly higher GTR rates. It thus prevents additional operations and reduces the number of tumor remnants. The complication rates do not exceed the incidences reported in the literature for primary transsphenoidal surgery. If complete tumor resection is not possible, iMRI guidance can facilitate tumor volume reduction.
authors.affiliation: Department of Neurosurgery, University Hospital Erlangen, Erlangen;
authors.forename: Sven
authors.initials: S
authors.lastname: Berkmann
authors.forename: Sven
authors.initials: S
authors.lastname: Schlaffer
authors.forename: Christopher
authors.initials: C
authors.lastname: Nimsky
authors.forename: Rudolf
authors.initials: R
authors.lastname: Fahlbusch
authors.forename: Michael
authors.initials: M
authors.lastname: Buchfelder
mesh_terms: D000236:Adenoma / Q000601:surgery*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000601:surgery; D019635:Neurosurgical Procedures / Q000379:methods*; D010901:Pituitary Function Tests; D010911:Pituitary Neoplasms / Q000601:surgery*; D012086:Reoperation; D012189:Retrospective Studies; D013100:Sphenoid Bone / Q000601:surgery; D025321:Surgery, Computer-Assisted / Q000379:methods*; D055815:Young Adult
keywords: DI = diabetes insipidus; FSH = follicle-stimulating hormone; GKS = Gamma Knife surgery; GTR = gross-total resection; LH = luteinizing hormone; NFA = nonfunctioning pituitary adenoma; VA = visual acuity; VF = visual field; iMRI = intraoperative MRI; intraoperative MRI; pituitary adenoma; pituitary surgery; poMRI = postoperative MRI; reoperation; transsphenoidal surgery; tumor recurrence