title: Intra- and interobserver variability of linear and volumetric measurements of brain metastases using contrast-enhanced magnetic resonance imaging.
abstract: OBJECTIVE
  To compare the intra- and interobserver variability of diameter and semiautomated volume measurements of brain metastases on contrast-enhanced magnetic resonance imaging (CE-MRI) data.
  
  
  METHODS
  About 75 MRI staging examinations of patients with metastasized renal cell carcinoma, thyroid cancer, or malignant melanoma (mean age, 56 years; range, 40-75 years) were included. Patients had been examined with a routine MRI protocol, including a CE 3D T1-weighted MP-RAGE sequence (1-mm slice thickness). MRI data were retrospectively analyzed using the OncoTREAT segmentation system (MeVis, Bremen, Germany, version 1.6). Volume of 355 enhancing brain metastases included in the analysis as well as the largest diameter according to Response Evaluation Criteria for Solid Tumors were measured by 2 radiologists. Intra- and interobserver variability was calculated.
  
  
  RESULTS
  Metastases (n = 355) had a mean diameter of 12.2 mm (range, 3.4-44.3 mm) and a mean volume of 1.4 cm(3) (range, 12-25.1 cm(3)). With respect to interobserver variability analysis revealed broader limits of agreement for response evaluation criteria for solid tumor measurements of all lesions (range, +/-27.8%-+/-33.0%; unsigned mean: 0.2%-2.5%) than for volume measurements (range, +/-21.4%-+/-23.3%; unsigned mean, 0.1%-0.3%) with statistically significant differences between diameter and volume measurements (P <or= 0.001). Limits of agreement were similar for intra- and interobserver comparisons.
  
  
  CONCLUSIONS
  Semiautomated segmentation of brain metastases on the basis of CE-MRI yielded reproducible volume measurements with a lower variability compared with linear measurements. Volumetry of contrast-enhancing brain metastases appears to be a suitable method for size determination in oncologic follow-up imaging.
authors.affiliation: Department of Radiology, Charité Campus Mitte, Charité-Universitätsmedizin Berlin, Berlin, Germany. christian.bauknecht@charite.de
authors.forename: Hans-Christian
authors.initials: HC
authors.lastname: Bauknecht
authors.forename: Valentina C
authors.initials: VC
authors.lastname: Romano
authors.forename: Patrik
authors.initials: P
authors.lastname: Rogalla
authors.forename: Randolf
authors.initials: R
authors.lastname: Klingebiel
authors.forename: Claudia
authors.initials: C
authors.lastname: Wolf
authors.forename: Lars
authors.initials: L
authors.lastname: Bornemann
authors.forename: Bernd
authors.initials: B
authors.lastname: Hamm
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Hein
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000556:secondary*; D003287:Contrast Media / Q000008:administration & dosage; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D009367:Neoplasm Staging; D015588:Observer Variation; D011859:Radiography; D047368:Tumor Burden
chemical_list: D003287:Contrast Media