title: Equivalence and precision of knee cartilage morphometry between different segmentation teams, cartilage regions, and MR acquisitions.
abstract: OBJECTIVE
  To compare precision and evaluate equivalence of femorotibial cartilage volume (VC) and mean cartilage thickness over total area of bone (ThCtAB.Me) from independent segmentation teams using identical Magnetic Resonance (MR) images from three series: sagittal 3D Dual Echo in the Steady State (DESS), coronal multi-planar reformat (DESS-MPR) of DESS and coronal 3D Fast Low Angle SHot (FLASH).
  
  
  METHODS
  Nineteen subjects underwent test-retest MR imaging at 3 T. Four teams segmented the cartilage using prospectively defined plate regions and rules. Mixed models analysis of the pooled data were used to evaluate the effect of acquisition, team and plate on precision and Pearson correlations and mixed models were used to evaluate equivalence.
  
  
  RESULTS
  Segmentation team differences dominated measurement variability in most cartilage regions for all image series. Precision of VC and ThCtAB.Me differed significantly by team and cartilage plate, but not between FLASH and DESS. Mean values of VC and ThCtAB.Me differed by team (P < 0.05) for DESS, FLASH and DESS-MPR. FLASH VC was 4-6% larger than DESS in the medial tibia and lateral central femur, and FLASH ThCtAB.Me was 5-6% larger in the medial tibia, but 4-8% smaller in the medial central femur. Correlations between DESS and FLASH for VC and ThCtAB.Me were high (r = 0.90-0.97), except for DESS vs FLASH medial central femur ThCtAB.Me (r = 0.81-0.83).
  
  
  CONCLUSIONS
  Cartilage morphology metrics from different image contrasts had similar precision, were generally equivalent, and may be combined for cross-sectional analyses if potential systematic offsets are accounted for. Data from different teams should not be pooled unless equivalence is demonstrated for cartilage metrics of interest.
authors.affiliation: Imaging Institute, Cleveland Clinic, Cleveland, OH 44195, USA. schneie1@ccf.org
authors.forename: E
authors.initials: E
authors.lastname: Schneider
authors.forename: M
authors.initials: M
authors.lastname: Nevitt
authors.forename: C
authors.initials: C
authors.lastname: McCulloch
authors.forename: F M
authors.initials: FM
authors.lastname: Cicuttini
authors.forename: J
authors.initials: J
authors.lastname: Duryea
authors.forename: F
authors.initials: F
authors.lastname: Eckstein
authors.forename: J
authors.initials: J
authors.lastname: Tamez-Pena
mesh_terms: D000328:Adult; D000368:Aged; D002358:Cartilage, Articular / Q000473:pathology*; D005260:Female; D005269:Femur / Q000473:pathology; D006801:Humans; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000503:physiopathology*; D010865:Pilot Projects; D011446:Prospective Studies; D015203:Reproducibility of Results; D013977:Tibia / Q000473:pathology