title: Three-dimensional computerized reconstruction. Illustration of incremental articular cartilage thinning.
abstract: OBJECTIVE
  The authors have addressed the ability of magnetic resonance (MR) imaging to resolve incremental thinning of articular cartilage by assessment of three-dimensional (3-D) and two-dimensional (2-D) representations.
  
  
  METHODS
  Using a porcine knee model, sequential cartilage shavings were characterized using a 3-D fat suppressed spoiled gradient-echo (SPGR) MR imaging protocol that provided good contrast between high-signal articular cartilage and lower signal surrounding tissues. Lesion dimensional measurements were made on both MR images and 3-D computerized reconstructions. Volumes of cartilage removed were approximately 0.06 mL.
  
  
  RESULTS
  Incremental articular cartilage thinning typically was apparent on 3-D reconstructed images. Three-dimensional articular cartilage reconstructions were effective in depicting location and orientation of shaved cartilage regions. Average percent error associated with length and with measurements based on 2-D MR images was approximately 19% for observer 1 and 33% for observer 2 when compared with direct measurements of the shaved cartilage. Average percent error of thickness measurements based on 2-D MR was approximately 21% for observer 1 and 37% for observer 2. Overall average errors associated with length, width, and thickness measurements were approximately 25%.
  
  
  CONCLUSIONS
  Incremental thinning of articular cartilage can be tracked qualitatively and quantitatively using 3-D computerized reconstructions and 2-D MR images. Errors associated with the quantitative measurements can be attributed to limitations of measurement methods and intrinsic limitation of MR resolution.
authors.affiliation: Imaging Resource Center, Kansas University School of Medicine, Kansas City 66103, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Tebben
authors.forename: T W
authors.initials: TW
authors.lastname: Pope
authors.forename: G
authors.initials: G
authors.lastname: Hinson
authors.forename: S
authors.initials: S
authors.lastname: Batnitzky
authors.forename: L H
authors.initials: LH
authors.lastname: Wetzel
authors.forename: D C
authors.initials: DC
authors.lastname: DePaolis
authors.forename: S
authors.initials: S
authors.lastname: Munns
authors.forename: S B
authors.initials: SB
authors.lastname: Wilkinson
authors.forename: M A
authors.initials: MA
authors.lastname: Gordon
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000473:pathology*; D004195:Disease Models, Animal; D007091:Image Processing, Computer-Assisted; D007719:Knee Joint / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015588:Observer Variation; D010003:Osteoarthritis / Q000175:diagnosis; D012680:Sensitivity and Specificity; D013552:Swine