title: dGEMRIC (delayed gadolinium-enhanced MRI of cartilage) indicates adaptive capacity of human knee cartilage.
abstract: Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) is a new imaging technique to estimate joint cartilage glycosaminoglycan content by T1-relaxation time measurements after penetration of the hydrophilic contrast agent Gd-DTPA(2-). This study compares dGEMRIC in age-matched healthy volunteers with different levels of physical activity: Group 1 (n = 12): nonexercising individuals; Group 2 (n = 16): individuals with physical exercise averaging twice weekly; Group 3 (n = 9): male elite runners. dGEMRIC was performed 2 hr after an intravenous injection of Gd-DTPA(2-) at 0.3 mmol/kg body weight. T1 differed significantly between the three different levels of physical exercise. T1 values (mean of medial and lateral femoral cartilage) for Groups 1, 2, and 3 were: 382 +/- 33, 424 +/- 22 and 476 +/- 36, respectively (ms, mean +/- SD) (P = 0.0004, 1 vs. 2 and 0.0002, 2 vs. 3). Irrespective of the exercise level, T1 was longer in lateral compared to medial femoral cartilage (P = 0.00005; n = 37). In conclusion, this cross-sectional study indicates that human knee cartilage adapts to exercise by increasing the glycosaminoglycan content. Furthermore, results suggest a compartmental difference within the knee with a higher glycosaminoglycan content in lateral compared to medial femoral cartilage. A higher proportion of extracellular water, i.e., larger distribution volume, may to some extent explain the high T1 in the elite runners.
authors.affiliation: Department of Orthopedics, Malmö University Hospital, Lund University, Malmö, Sweden.
authors.forename: Carl Johan
authors.initials: CJ
authors.lastname: Tiderius
authors.forename: Jonas
authors.initials: J
authors.lastname: Svensson
authors.forename: Peter
authors.initials: P
authors.lastname: Leander
authors.forename: Thorsson
authors.initials: T
authors.lastname: Ola
authors.forename: Leif
authors.initials: L
authors.lastname: Dahlberg
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000378:metabolism / Q000502:physiology*; D003287:Contrast Media; D015444:Exercise / Q000502:physiology*; D005260:Female; D019786:Gadolinium DTPA; D006025:Glycosaminoglycans / Q000378:metabolism; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male
chemical_list: D003287:Contrast Media; D006025:Glycosaminoglycans; D019786:Gadolinium DTPA