title: Surveillance after resection of vestibular schwannoma: measurement techniques and predictors of growth.
abstract: OBJECTIVE
  To compare different methods of measuring tumor growth after resection of vestibular schwannoma and to identify predictors of growth.
  
  
  METHODS
  Retrospective case review.
  
  
  METHODS
  Tertiary referral center, inpatient surgery with ambulatory follow-up.
  
  
  METHODS
  All patients who underwent vestibular schwannoma resection by the senior author from September 1991 to April 2012 and had two or more postoperative MRI scans.
  
  
  METHODS
  Vestibular schwannoma resection. Measurement of tumor size and enhancement pattern on postoperative magnetic resonance imaging scans.
  
  
  METHODS
  Tumor size as measured in one (linear), two (planar), and three (volumetric) dimensions using standard radiology workstation tools versus time elapsed since surgical resection.
  
  
  RESULTS
  Eighty-eight patients were included with mean follow-up of 3.9 years. Linear measurement of tumor size was found to have modest correlation with planar and volumetric measurements. Excellent correlation was found between the planar and volumetric methods. Nodular enhancement increased risk for tumor growth (OR 6.25, p = 0.03 on planar analysis). If there was growth, tumors with nodular enhancement typically showed increase in size beginning 2 years postoperatively, whereas those with linear or no enhancement were typically stable in size through 5 years. Younger age and larger preoperative tumor size were also risk factors for growth (OR 0.9/p = 0.01 and OR 1.09/p = 0.02).
  
  
  CONCLUSIONS
  Simple planar measurement is an efficient method that correlates well with the more time-consuming volumetric method. The major risk factor for tumor growth is nodular enhancement on a baseline scan, a finding that warrants annual MRI beginning 2 years postoperatively. Younger age and larger preoperative size minimally increased risk of growth.
authors.affiliation: *Department of Otolaryngology-Head and Neck Surgery, Weill Cornell Medical College, New York, New York; †Department of Medicine, Weill Cornell Medical College, New York, New York; ‡Tufts University School of Medicine, Boston, Massachusetts; §Department of Radiology, Weill Cornell Medical College, New York, New York; ∥Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York; ¶Department of Neurosurgery, George Washington University School of Medicine, Washington DC; #Department of Neurological Surgery, Weill Cornell Medical College, New York, New York; **Department of Neurosurgery, Memorial Sloan-Kettering Cancer Center, New York, New York; ††Weill Cornell Medical College, New York, New York; ‡‡Department of Otolaryngology-Head and Neck Surgery, Weill Cornell Medical College, New York, New York; and §§Department of Neurosurgery, Memorial Sloan-Kettering Cancer Center, New York, New York.
authors.forename: Shan
authors.initials: S
authors.lastname: Tang
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Griffin
authors.forename: Julian A
authors.initials: JA
authors.lastname: Waksal
authors.forename: C Douglas
authors.initials: CD
authors.lastname: Phillips
authors.forename: Carl E
authors.initials: CE
authors.lastname: Johnson
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Comunale
authors.forename: Sasan
authors.initials: S
authors.lastname: Karimi
authors.forename: Tiffany L
authors.initials: TL
authors.lastname: Powell
authors.forename: Philip E
authors.initials: PE
authors.lastname: Stieg
authors.forename: Philip H
authors.initials: PH
authors.lastname: Gutin
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Brown
authors.forename: Matthew
authors.initials: M
authors.lastname: Sheehan
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Selesnick
mesh_terms: D000328:Adult; D000367:Age Factors; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000473:pathology / Q000601:surgery*; D011184:Postoperative Period; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome