title: Semiautomated volumetric measurement on postcontrast MR imaging for analysis of recurrent and residual disease in glioblastoma multiforme.
abstract: OBJECTIVE
  A limitation in postoperative monitoring of patients with glioblastoma is the lack of objective measures to quantify residual and recurrent disease. Automated computer-assisted volumetric analysis of contrast-enhancing tissue represents a potential tool to aid the radiologist in following these patients. In this study, we hypothesize that computer-assisted volumetry will show increased precision and speed over conventional 1D and 2D techniques in assessing residual and/or recurrent tumor.
  
  
  METHODS
  This retrospective study included patients with native glioblastomas with MR imaging performed at 24-48 hours following resection and 2-4 months postoperatively. 1D and 2D measurements were performed by 2 neuroradiologists with Certificates of Added Qualification. Volumetry was performed by using manual segmentation and computer-assisted volumetry, which combines region-based active contours and a level set approach. Tumor response was assessed by using established 1D, 2D, and volumetric standards. Manual and computer-assisted volumetry segmentation times were compared. Interobserver correlation was determined among 1D, 2D, and volumetric techniques.
  
  
  RESULTS
  Twenty-nine patients were analyzed. Discrepancy in disease status between 1D and 2D compared with computer-assisted volumetry was 10.3% (3/29) and 17.2% (5/29), respectively. The mean time for segmentation between manual and computer-assisted volumetry techniques was 9.7 minutes and <1 minute, respectively (P < .01). Interobserver correlation was highest for volumetric measurements (0.995; 95% CI, 0.990-0.997) compared with 1D (0.826; 95% CI, 0.695-0.904) and 2D (0.905; 95% CI, 0.828-0.948) measurements.
  
  
  CONCLUSIONS
  Computer-assisted volumetry provides a reproducible and faster volumetric assessment of enhancing tumor burden, which has implications for monitoring disease progression and quantification of tumor burden in treatment trials.
authors.affiliation: From the Departments of Radiology (D.S.C., J.Q., X.G., V.Z.M., L.H.S., A.L., B.Z., C.G.F.).
authors.forename: D S
authors.initials: DS
authors.lastname: Chow
authors.forename: J
authors.initials: J
authors.lastname: Qi
authors.forename: X
authors.initials: X
authors.lastname: Guo
authors.forename: V Z
authors.initials: VZ
authors.lastname: Miloushev
authors.forename: F M
authors.initials: FM
authors.lastname: Iwamoto
authors.forename: J N
authors.initials: JN
authors.lastname: Bruce
authors.forename: A B
authors.initials: AB
authors.lastname: Lassman
authors.forename: L H
authors.initials: LH
authors.lastname: Schwartz
authors.forename: A
authors.initials: A
authors.lastname: Lignelli
authors.forename: B
authors.initials: B
authors.lastname: Zhao
authors.forename: C G
authors.initials: CG
authors.lastname: Filippi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D005909:Glioblastoma / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology*; D018365:Neoplasm, Residual; D059906:Neuroimaging / Q000379:methods*; D012189:Retrospective Studies; D047368:Tumor Burden
chemical_list: D003287:Contrast Media