T2 of articular cartilage in the presence of Gd-DTPA2-

T-2 information, and delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) are both used to characterize articular cartilage. They are currently obtained in separate studies because Gd-DTPA(2-) (which is needed for dGEMRIC) affects the inherent T-2 information. In this study, T-2 was simulated and then measured at 8.45 T in 20 sections from two human osteochondral samples equilibrated with and without Gd-DTPA(2-). Both the simulations and data demonstrated that Gd-DTPA(2-) provides a non-negligible mechanism for relaxation, especially with higher 0 mM) equilibrating Gd-DTPA(2-) concentrations, and in areas of tissue with high T. (due to weak inherent T-2 mechanisms) and high tissue Gd-DTPA(2-) (due to a low glycosaminoglycan concentration), Nonetheless, T-2-weighted images of cartilage equilibrated in 1 mM Gd-DTPA(2-) showed similar T-2 contrast with and without Gd-DTPA(2-), demonstrating that the impact on T-2 was not great enough to affect identification of T-2 lesions. However, T-2 maps of the same samples showed loss of conspicuity of T-2 abnormalities. We back-calculated inherent T-2's (T-2,T-bc) using a T-2-relaxivity value from a 20% protein phantom (r(2) = 9.27 +/- 0.09 mM(-1)s(-1)) and the Gd-DTPA2- concentration calculated from T-1,T-Gd. The back-calculation restored the inherent T-2 conspicuity, and a correlation between T-2 and T-2,T-bc of r = 0.934 (P < 0.0001) was found for 80 regions of interest (ROIs) in the sections. Back-calculation of T-2 is therefore a viable technique for obtaining T-2 Maps at high equilibrating Gd-DTPA(2-) concentrations. With T-2-weighted images and/or low equilibrating Gd-DTPA(2-) concentrations, it may be feasible to obtain both T-2 and dGEMRIC information in the presence of Gd-DTPA(2-) without such corrections. These conditions can be designed into ex vivo studies of cartilage. They appear to be applicable for clinical T-2 studies, since pilot clinical data at 1.5 T from three volunteers demonstrated that calculated T-2 maps are comparable before and after "double dose" Gd-DTPA(2-) (as utilized in clinical dGEMRIC studies). Therefore, it may be possible to perform a comprehensive clinical examination of dGEMRIC, T-2, and cartilage volume in one scanning session without T-2 data correction. (C) 2004 Wiley-Liss, Inc.