title: The in vivo effects of unloading and compression on T1-Gd (dGEMRIC) relaxation times in healthy articular knee cartilage at 3.0 Tesla.
abstract: OBJECTIVE
  The purpose was to investigate the in vivo effects of unloading and compression on T1-Gd relaxation times in healthy articular knee cartilage.
  
  
  METHODS
  Ten volunteers were enrolled, and dGEMRIC images of their right knee joints were obtained using 3.0-T MR at three timepoints: directly following exercise ("baseline"), approximately 15 min after unloading ("unloading") and during application of a compressive force (50% of the body weight) generated by a loading device via a footplate ("compression").
  
  
  RESULTS
  Our analysis of variance of pooled data from all cartilage zones demonstrated a significant mean T1-Gd decrease of 56.6 ms between baseline and compression (p < 0.001), and a significant mean decrease of 42.1 ms between unloading and compression (p < 0.001). No significant difference was found between baseline and unloading. Higher mean T1-Gd values were observed in the cartilage contact zone (central femoral and tibial zones; 698.3 +/- 162.2 ms) than in the non-contact zone (anterior and posterior femoral and tibial zones, and dorsal femoral zone; 662.9 +/- 149.3 ms; p < 0.01).
  
  
  CONCLUSIONS
  T1-Gd times appear to be sensitive to mechanical cartilage stress, and thus, further studies are warranted that investigate the relationship between the biochemical load response and the biomechanical properties of articular cartilage.
authors.affiliation: Department of Radiology, MR Center, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria.
authors.forename: Marius E
authors.initials: ME
authors.lastname: Mayerhoefer
authors.forename: Goetz H
authors.initials: GH
authors.lastname: Welsch
authors.forename: Tallal C
authors.initials: TC
authors.lastname: Mamisch
authors.forename: Franz
authors.initials: F
authors.lastname: Kainberger
authors.forename: Michael
authors.initials: M
authors.lastname: Weber
authors.forename: Stefan
authors.initials: S
authors.lastname: Nemec
authors.forename: Klaus M
authors.initials: KM
authors.lastname: Friedrich
authors.forename: Albert
authors.initials: A
authors.lastname: Dirisamer
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
mesh_terms: D000328:Adult; D002358:Cartilage, Articular / Q000033:anatomy & histology* / Q000502:physiology*; D019245:Compressive Strength / Q000502:physiology; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology* / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D005082:Physical Exertion / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult