title: Intraobserver variability in the MR determination of tumor volume in squamous cell carcinoma of the pharynx.
abstract: OBJECTIVE
  If tumor volumes are to be used for evaluating responses to treatment and long-term outcomes of patients with primary pharyngeal carcinomas, the reproducibility of these measurements must be established. We determined the intraobserver variability of MR imaging-based volume measurements of these cancers and their regional metastases.
  
  
  METHODS
  We used an interactive computer program (IDL) that enables the extraction of tumor volumes from 3D MR data to obtain 202 volume measurements in 17 patients with pharyngeal carcinoma (two to five time points each). The primary cancer and largest nodal mass were manually outlined on every T2-weighted image of each MR study. The same neuroradiologist reanalyzed this MR dataset 2-41 weeks later. Measurement error and percentage measurement error (intraobserver variability) were determined. Differences in intraobserver variability between primary lesions and nodes, as well as between stages of treatment were tested with a Wilcoxon rank sum test.
  
  
  RESULTS
  The mean and median percentage measurement errors, respectively, were 13% and 12% (range, 0-53%; 95% CI: 10%, 16%) for primary tumors and 9% and 7% (range, 0-37%; 95% CI: 7%, 12%) for nodal metastases. The difference in the percentage measurement error between primary lesions and cervical nodes approached statistical significance (P =.07). Differences in the variation of volume measurements based on the stage of therapy were significant (P =.01).
  
  
  CONCLUSIONS
  Our results suggest that MR imaging-based tumor volumes are reliably reproducible. Such measurements may be important in predicting patient outcome, determining appropriate therapy, and conducting patient follow-up.
authors.affiliation: Department of Radiology, University of Pennsylvania Medical Center, Philadelphia 19104, USA.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Gordon
authors.forename: Laurie A
authors.initials: LA
authors.lastname: Loevner
authors.forename: Amita
authors.initials: A
authors.lastname: Shukla-Dave
authors.forename: Regina O
authors.initials: RO
authors.lastname: Redfern
authors.forename: Adina I
authors.initials: AI
authors.lastname: Sonners
authors.forename: Alex M
authors.initials: AM
authors.lastname: Kilger
authors.forename: Mark A
authors.initials: MA
authors.lastname: Elliott
authors.forename: Mitchell
authors.initials: M
authors.lastname: Machtay
authors.forename: Randal S
authors.initials: RS
authors.lastname: Weber
authors.forename: Jerry D
authors.initials: JD
authors.lastname: Glickson
authors.forename: David I
authors.initials: DI
authors.lastname: Rosenthal
mesh_terms: D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010610:Pharyngeal Neoplasms / Q000473:pathology*