Delayed contrast-enhanced MRI of cartilage: comparison of nonionic and ionic contrast agents.

The objective of this study was to evaluate if cartilage fixed charge density is the only factor determining the distribution of the measured delayed gadolinium-enhanced magnetic resonance imaging of cartilage index, T(1) (Gd-DTPA(2-) ), across cartilage in the clinical delayed gadolinium-enhanced magnetic resonance imaging of cartilage protocol. Nineteen subjects with osteoarthritis and 14 controls were included. Cartilage T(1) (Gd) was measured following administration of 0.2 mmol kg(-1) of nonionic (Gd-DTPA-BMA) and, at a different date, anionic (Gd-DTPA(2-). T(1) (Gd-DTPA-BMA) was plotted against T(1) (Gd-DTPA(2-); a slope of 0 would indicate domination by charge effects; a nonzero slope would suggest that other factors influence T(1) (Gd-DTPA-BMA), and hence potentially T(1) (Gd-DTPA(2-). The low slope of the curve found in osteoarthritis subjects (0.31) indicates that Gd-DTPA-BMA penetrated most osteoarthritis cartilage to the same extent, and T(1) (Gd-DTPA-BMA) did not differentiate cartilages, which were differentiated by T(1) (Gd-DTPA(2-). The higher slopes in control subjects (0.88) are possibly due to inhibited transport of contrast agent into healthier cartilage, potentially exaggerated by the fast body clearance of the nonionic contrast agent. Overall, the use of anionic Gd-DTPA(2-) for delayed gadolinium-enhanced magnetic resonance imaging of cartilage is indicated for better discrimination of the health status of cartilage. Future studies could be designed to use contrast-enhanced dynamics to understand the transport properties of tissues in the joint and to evaluate the concentration of tissue constituents.