title: Diffusion-tensor imaging of human articular cartilage specimens with early signs of cartilage damage.
abstract: OBJECTIVE
  To assess the use of diffusion-tensor (DT) imaging of articular cartilage to detect and grade early cartilage damage in human specimens with early signs of cartilage damage.
  
  
  METHODS
  This study was approved by the institutional review board. Forty-three cartilage-on-bone samples drilled from 21 human patellae were examined with 17.6-T magnetic resonance (MR) imaging and a diffusion-weighted spin-echo sequence (spatial resolution, 50 × 100 × 800 μm). Subsequently, samples underwent histologic analysis with safranin O staining. Cartilage damage on safranin O histologic slides was quantified with Osteoarthritis Research Society International (OARSI) grades; grades ranged from 0 (healthy) to 6 (bone remodeling). Maps of longitudinal diffusivity (λ(l)), transverse diffusivity (λ(t)), mean diffusivity (MD), and fractional anisotropy (FA) were calculated. Cartilage was segmented, and region of interest (ROI) analysis was performed and compared with histologic findings. Significant differences in MR parameters between the OARSI groups were assessed with the Tukey test. The value of DT imaging in the diagnosis and grading of cartilage damage was assessed with logistic regression analysis.
  
  
  RESULTS
  Samples had OARSI grades of 0 (n = 14), 1 (n = 11), 2 (n = 12), 3 (n = 4), and 4 (n = 2). Samples with an OARSI grade greater than 0 had significantly increased λ(l), λ(t), and MD (7%-25% increase) in the superficial cartilage growing deeper into cartilage with increasing OARSI grade. Samples with an OARSI grade greater than 0 showed significantly decreased FA in the deep cartilage (-25% to -35% decrease), suggesting that changes in the collagen architecture may occur early in cartilage degradation. DTI showed excellent performance in the detection of cartilage damage (accuracy, 0.95; 41 of 43 samples) and good performance in the grading of cartilage damage (accuracy, 0.74; 32 of 43 samples).
  
  
  CONCLUSIONS
  DT imaging of articular cartilage can enable physicians to detect and grade early cartilage damage.
authors.affiliation: Department of Radiology, New York University Langone Medical Center, 660 First Ave, 4th Floor, New York, NY 10016, USA. jose.raya@nyumc.org
authors.forename: José G
authors.initials: JG
authors.lastname: Raya
authors.forename: Gerd
authors.initials: G
authors.lastname: Melkus
authors.forename: Silvia
authors.initials: S
authors.lastname: Adam-Neumair
authors.forename: Olaf
authors.initials: O
authors.lastname: Dietrich
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Mützel
authors.forename: Maximilian F
authors.initials: MF
authors.lastname: Reiser
authors.forename: Reinhard
authors.initials: R
authors.lastname: Putz
authors.forename: Thorsten
authors.initials: T
authors.lastname: Kirsch
authors.forename: Peter M
authors.initials: PM
authors.lastname: Jakob
authors.forename: Christian
authors.initials: C
authors.lastname: Glaser
mesh_terms: D000293:Adolescent; D000328:Adult; D002358:Cartilage, Articular / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult