title: A novel, reproducible, and objective method for volumetric magnetic resonance imaging assessment of enhancing glioblastoma.
abstract: OBJECTIVE
  Robust methodology that allows objective, automated, and observer-independent measurements of brain tumor volume, especially after resection, is lacking. Thus, determination of tumor response and progression in neurooncology is unreliable. The objective of this study was to determine if a semi-automated volumetric method for quantifying enhancing tissue would perform with high reproducibility and low interobserver variability.
  
  
  METHODS
  Fifty-seven MR images from 13 patients with glioblastoma were assessed using our method, by 2 neuroradiologists, 1 neurosurgeon, 1 neurosurgical resident, 1 nurse practitioner, and 1 medical student. The 2 neuroradiologists also performed traditional 1-dimensional (1D) and 2-dimensional (2D) measurements. Intraclass correlation coefficients (ICCs) assessed interobserver variability between measurements. Radiological response was determined using Response Evaluation Criteria In Solid Tumors (RECIST) guidelines and Macdonald criteria. Kappa statistics described interobserver variability of volumetric radiological response determinations.
  
  
  RESULTS
  There was strong agreement for 1D (RECIST) and 2D (Macdonald) measurements between neuroradiologists (ICC = 0.42 and 0.61, respectively), but the agreement using the authors' novel automated approach was significantly stronger (ICC = 0.97). The volumetric method had the strongest agreement with regard to radiological response (κ = 0.96) when compared with 2D (κ = 0.54) or 1D (κ = 0.46) methods. Despite diverse levels of experience of the users of the volumetric method, measurements using the volumetric program remained remarkably consistent in all users (0.94).
  
  
  CONCLUSIONS
  Interobserver variability using this new semi-automated method is less than the variability with traditional methods of tumor measurement. This new method is objective, quick, and highly reproducible among operators with varying levels of expertise. This approach should be further evaluated as a potential standard for response assessment based on contrast enhancement in brain tumors.
authors.affiliation: Division of Neurosurgery, Department of Surgery.
authors.forename: Charles W
authors.initials: CW
authors.lastname: Kanaly
authors.forename: Ankit I
authors.initials: AI
authors.lastname: Mehta
authors.forename: Dale
authors.initials: D
authors.lastname: Ding
authors.forename: Jenny K
authors.initials: JK
authors.lastname: Hoang
authors.forename: Peter G
authors.initials: PG
authors.lastname: Kranz
authors.forename: James E
authors.initials: JE
authors.lastname: Herndon
authors.forename: April
authors.initials: A
authors.lastname: Coan
authors.forename: Ian
authors.initials: I
authors.lastname: Crocker
authors.forename: Anthony F
authors.initials: AF
authors.lastname: Waller
authors.forename: Allan H
authors.initials: AH
authors.lastname: Friedman
authors.forename: David A
authors.initials: DA
authors.lastname: Reardon
authors.forename: John H
authors.initials: JH
authors.lastname: Sampson
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000473:pathology*; D018450:Disease Progression; D005909:Glioblastoma / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D047368:Tumor Burden
keywords: ICC = intraclass correlation coefficient; RANO = Response Assessment in Neuro-Oncology Working Group; RECIST = Response Evaluation Criteria In Solid Tumors; brain neoplasm; disease progression; glioma; magnetic resonance imaging; oncology; recurrence