title: Cross-relaxation imaging of human patellar cartilage in vivo at 3.0T.
abstract: OBJECTIVE
  To compare quantitative magnetization transfer (qMT) parameters of patellar cartilage measured using cross-relaxation imaging (CRI) in asymptomatic volunteers and patients with osteoarthritis.
  
  
  METHODS
  The study was performed with Institutional Review Board approval and with all subjects signing informed consent. CRI of the knee joint was performed at 3.0T on 20 asymptomatic volunteers and 11 patients with osteoarthritis. The fraction of macromolecular bound protons (f), the exchange rate constant between macromolecular bound protons and free water protons (k), and the T2 relaxation time of macromolecular bound protons (T2(B)) of patellar cartilage were measured. Mann-Whitney-Wilcoxon rank-sum tests were used to compare qMT parameters between asymptomatic volunteers and patients with osteoarthritis.
  
  
  RESULTS
  Average f, k, and T2(B) of patellar cartilage was 12.46%, 7.22 s(-1), and 6.49 μs respectively for asymptomatic volunteers and 12.80%, 6.13 s(-1), and 6.80 μs respectively for patients with osteoarthritis. There were statistically significant differences between groups of subjects for k (P < 0.01) and T2(B) (P < 0.0001) but not f (P = 0.38) of patellar cartilage.
  
  
  CONCLUSIONS
  Patients with osteoarthritis had significantly lower k and significantly higher T2(B) of patellar cartilage than asymptomatic volunteers which suggests that qMT parameters can detect changes in the macromolecular matrix of degenerative cartilage.
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-3252, USA. Electronic address: nade@cae.wisc.edu.
authors.forename: N
authors.initials: N
authors.lastname: Sritanyaratana
authors.affiliation: Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-3252, USA; Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-3252, USA.
authors.forename: A
authors.initials: A
authors.lastname: Samsonov
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-3252, USA.
authors.forename: P
authors.initials: P
authors.lastname: Mossahebi
authors.affiliation: Department of Orthopedic Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-3252, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Wilson
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-3252, USA; Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-3252, USA.
authors.forename: W F
authors.initials: WF
authors.lastname: Block
authors.affiliation: Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-3252, USA.
authors.forename: R
authors.initials: R
authors.lastname: Kijowski
mesh_terms: D000328:Adult; D002358:Cartilage, Articular / Q000473:pathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology*; D010329:Patella / Q000473:pathology*; D057071:Patellofemoral Joint / Q000473:pathology*; D059629:Signal-To-Noise Ratio; D055815:Young Adult
keywords: Cartilage; MRI; Magnetization transfer; Osteoarthritis