dGEMRIC (delayed gadolinium‐enhanced MRI of cartilage) indicates adaptive capacity of human knee cartilage

Delayed gadolinium‐enhanced MRI of cartilage (dGEMRIC) is a new imaging technique to estimate joint cartilage glycosaminoglycan content by T 1 ‐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. T 1 differed significantly between the three different levels of physical exercise. T 1 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, T 1 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 T 1 in the elite runners. Magn Reson Med 51:286–290, 2004. © 2004 Wiley‐Liss, Inc.