title: Diffusion-weighted imaging for the follow-up of patients after matrix-associated autologous chondrocyte transplantation.
abstract: OBJECTIVE
  To evaluate the use of diffusion-weighted imaging (DWI) for the assessment of cartilage maturation in patients after matrix-associated autologous chondrocyte transplantation (MACT).
  
  
  METHODS
  Fifteen patients after MACT were examined by 3.0-T magnetic-resonance-tomography; the examination was up to 13 month after surgery in group 1, and later than 13 month after surgery in group 2. Both groups had a follow-up one-year later. DWI was acquired using a steady-state gradient-echo sequence. Mean values of the diffusion quotients of regions of interest within cartilage repair tissue and of reference regions were assessed. Each region-of-interest was subdivided into a deep, and a superficial area.
  
  
  RESULTS
  Mean diffusion quotients of cartilage repair tissues were 1.44 (baseline), and 1.44 (follow-up). Mean diffusion quotients of reference tissues were 1.29 (baseline) and 1.28 (follow-up). At the follow-up diffusion quotients of cartilage repair tissue were significantly higher than those of reference cartilage. In group 1 the diffusion quotients were significantly lower at the follow-up (1.45 versus 1.65); in group 2 no statistically significant differences between follow-up (1.39) and baseline (1.41) were found. Reference cartilages and cartilage repair tissues of group 2 showed a decrease of diffusion quotients from the deep to the superficial area being stable at the follow-up. In group 1 initially a significant increase (1.49 versus 1.78) of the diffusion quotients from deep to superficial area of the cartilage repair tissue was found changing into a decrease (1.65 versus 1.52) at the follow-up.
  
  
  CONCLUSIONS
  DWI detected changes of diffusion within cartilage repair tissue that may reflect cartilage maturation. Changes in diffusity occurred up to two years after surgery and were stable later. Zonal variations within cartilage could be measured.
authors.affiliation: Medical University Vienna, Department of Radiology, MR Center of Excellence, Vienna, Austria. klaus.friedrich@meduniwien.ac.at
authors.forename: Klaus M
authors.initials: KM
authors.lastname: Friedrich
authors.forename: Tallal C
authors.initials: TC
authors.lastname: Mamisch
authors.forename: Christina
authors.initials: C
authors.lastname: Plank
authors.forename: Georg
authors.initials: G
authors.lastname: Langs
authors.forename: Stefan
authors.initials: S
authors.lastname: Marlovits
authors.forename: Erich
authors.initials: E
authors.lastname: Salomonowitz
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
authors.forename: Götz
authors.initials: G
authors.lastname: Welsch
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002358:Cartilage, Articular / Q000473:pathology*; D019902:Chondrocytes / Q000637:transplantation*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D014182:Transplantation, Autologous; D016896:Treatment Outcome