title: Pituitary surgery and volumetric assessment of extent of resection: a paradigm shift in the use of intraoperative magnetic resonance imaging.
abstract: OBJECTIVE
  The aim of this study was to quantitatively assess the role of intraoperative high-field 3-T MRI (3T-iMRI) in improving the gross-total resection (GTR) rate and the extent of resection (EOR) in endoscopic transsphenoidal surgery (TSS) for pituitary adenomas.
  
  
  METHODS
  Radiological and clinical data from a prospective database were retrospectively analyzed. Volumetric measurements of adenoma volumes pre-, intraoperatively, and 3 months postoperatively were performed in a consecutive series of patients who had undergone endoscopic TSS. The quantitative contribution of 3T-iMRI was measured as a percentage of the additional rate of GTR and of the EOR achieved after 3T-iMRI.
  
  
  RESULTS
  The cohort consisted of 50 patients (51 operations) harboring 33 nonfunctioning and 18 functioning pituitary adenomas. Mean adenoma diameter and volume were 21.1 mm (range 5-47 mm) and 5.23 cm(3) (range 0.09-22.14 cm(3)), respectively. According to Knosp's classification, 10 cases were Grade 0; 8, Grade 1; 17, Grade 2; 12, Grade 3; and 4, Grade 4. Gross-total resection was the surgical goal (targeted [t]GTR) in 34 of 51 operations and was initially achieved in 16 (47%) of 34 at 3T-iMRI and in 30 (88%) of 34 cases after further resection. In this subgroup, the EOR increased from 91% at 3T-iMRI to 99% at the 3-month MRI (p < 0.05). In the 17 cases in which subtotal resection (STR) had been planned (tSTR), the EOR increased from 79% to 86% (p < 0.05) and GTR could be achieved in 1 case. Intrasellar remnants were present in 20 of 51 procedures at 3T-iMRI and in only 5 (10%) of 51 procedures after further resection (median volume 0.15 cm(3)). Overall, the use of 3T-iMRI led to further resection in 27 (53%) of 51 procedures and permitted GTR in 15 (56%) of these 27 procedures; thus, the GTR rate in the entire cohort increased from 31% (16 of 51) to 61% (31 of 51) and the EOR increased from 87% to 95% (p < 0.05).
  
  
  CONCLUSIONS
  The use of high-definition 3T-iMRI allowed precise visualization and quantification of adenoma remnant volume. It helped to increase GTR and EOR rates in both tGTR and tSTR patient groups. Moreover, it helped to achieve low rates of intrasellar remnants. These data support the use of 3T-iMRI to achieve maximal, safe adenoma resection.
authors.affiliation: Departments of 1 Neurosurgery.
authors.forename: Carlo
authors.initials: C
authors.lastname: Serra
authors.affiliation: Departments of 1 Neurosurgery.
authors.forename: Jan-Karl
authors.initials: JK
authors.lastname: Burkhardt
authors.affiliation: Departments of 1 Neurosurgery.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Esposito
authors.affiliation: Departments of 1 Neurosurgery.
authors.forename: Oliver
authors.initials: O
authors.lastname: Bozinov
authors.affiliation: Neuroradiology.
authors.forename: Athina
authors.initials: A
authors.lastname: Pangalu
authors.affiliation: Neuroradiology.
authors.forename: Antonios
authors.initials: A
authors.lastname: Valavanis
authors.affiliation: Otorhinolaryngology, Head and Neck Surgery, and.
authors.forename: David
authors.initials: D
authors.lastname: Holzmann
authors.affiliation: Endocrinology and Diabetes, University Hospital of Zürich, University of Zürich, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schmid
authors.affiliation: Departments of 1 Neurosurgery.
authors.forename: Luca
authors.initials: L
authors.lastname: Regli
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging* / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D010911:Pituitary Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery; D011446:Prospective Studies; D012189:Retrospective Studies; D047368:Tumor Burden; D055815:Young Adult
keywords: ACTH = adrenocorticotropic hormone; EOR = extent of resection; GH = growth hormone; GTR = gross-total resection; NFA = nonfunctioning pituitary adenoma; PA = pituitary adenoma; STR = subtotal resection; TSS = transsphenoidal surgery; TVDT = tumor volume doubling time; endoscopy; iMRI = intraoperative MRI; intraoperative MRI; pituitary adenoma; t = targeted; transsphenoidal surgery; volumetry