title: Sensitivity to change of cartilage morphometry using coronal FLASH, sagittal DESS, and coronal MPR DESS protocols--comparative data from the Osteoarthritis Initiative (OAI).
abstract: OBJECTIVE
  The Osteoarthritis Initiative (OAI) is targeted at identifying sensitive biomarkers and risk factors of symptomatic knee osteoarthritis (OA) onset and progression. Quantitative cartilage imaging in the OAI relies on validated fast low angle shot (FLASH) sequences that suffer from relatively long acquisition times, and on a near-isotropic double echo steady-state (DESS) sequence. We therefore directly compared the sensitivity to cartilage thickness changes and the correlation of these protocols longitudinally.
  
  
  METHODS
  Baseline (BL) and 12 month follow-up data of 80 knees were acquired using 1.5 mm coronal FLASH and 0.7 mm sagittal DESS (sagDESS) sequences. In these and in 1.5 mm coronal multi-planar reconstructions (MPR) of the DESS the medial femorotibial cartilage was segmented with blinding to acquisition order. In the weight-bearing femoral condyle, a 60% (distance between the trochlear notch and the posterior femur) and a 75% region of interest (ROI) were studied.
  
  
  RESULTS
  The standardized response mean (SRM = mean change/standard deviation of change) in central medial femorotibial (cMFTC) cartilage thickness was -0.34 for coronal FLASH, -0.37 for coronal MPR DESS, -0.36 for sagDESS with the 60% ROI, and -0.38 for the 75% ROI. Using every second 0.7 mm sagittal slice (DESS) yielded similar SRMs in cMFTC for the 60% and 75% ROI from odd (-0.35/-0.36) and even slice numbers (-0.36/-0.39), respectively. BL cartilage thickness displayed high correlations (r > or = 0.94) between the three protocols; the correlations of longitudinal changes were > or = 0.79 (Pearson) and > or = 0.45 (Spearman).
  
  
  CONCLUSIONS
  Cartilage morphometry with FLASH and DESS displays similar longitudinal sensitivity to change. Analysis of every second slice of the 0.7 mm DESS provides adequate sensitivity to change.
authors.affiliation: Chondrometrics GmbH, Ainring, Germany. wolfgang.wirth@pmu.ac.at
authors.forename: W
authors.initials: W
authors.lastname: Wirth
authors.forename: M
authors.initials: M
authors.lastname: Nevitt
authors.forename: M-P
authors.initials: MP
authors.lastname: Hellio Le Graverand
authors.forename: O
authors.initials: O
authors.lastname: Benichou
authors.forename: D
authors.initials: D
authors.lastname: Dreher
authors.forename: R Y
authors.initials: RY
authors.lastname: Davies
authors.forename: J
authors.initials: J
authors.lastname: Lee
authors.forename: K
authors.initials: K
authors.lastname: Picha
authors.forename: A
authors.initials: A
authors.lastname: Gimona
authors.forename: S
authors.initials: S
authors.lastname: Maschek
authors.forename: M
authors.initials: M
authors.lastname: Hudelmaier
authors.forename: F
authors.initials: F
authors.lastname: Eckstein
mesh_terms: D000368:Aged; D002358:Cartilage, Articular / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007719:Knee Joint / Q000473:pathology; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology*; D012680:Sensitivity and Specificity