Value of precontrast T1 for dGEMRIC of native articular cartilage.

Purpose To evaluate if the difference between pre- and post-Gd-DTPA^2- relaxation rate (ΔR₁) provides better differentiation of osteoarthritic patients (OA) from healthy subjects (HS) with dGEMRIC, as compared to post-Gd-DTPA^2- spin-lattice relaxation time (T_1Gd). Materials and Methods Seventeen OA and 14 HS underwent pre- and 90 minutes postcontrast (Gd-DTPA^2-) magnetic resonance imaging (MRI) of the knee, using inversion recovery fast spin-echo and/or Lock-Locker sequences for T₁ mapping. Effect sizes for T_1pre, T_1Gd, and ΔR₁ were calculated, and receiver operating characteristic (ROC) curve and regression analysis were also performed to assess the effectiveness of each parameter in the separation of OA and HS. Results T_1Gd and ΔR₁ were almost identical in terms of areas under ROC curves (0.903 and 0.914, respectively), and effect sizes (1.34 and 1.31, respectively). These were significantly higher than T_1pre. In addition, a high inverse correlation was observed between ΔR₁ vs. T_1Gd (R = 0.96). Conclusion Either T_1Gd or ΔR₁ could be used as an index in the evaluation of native cartilage. However, considering the practical logistical cost involved in terms of time and effort to acquire precontrast T₁ measurements, our data further support the continued use of T_1Gd as the dGEMRIC index in the evaluation of native cartilage. J. Magn. Reson. Imaging 2009;29:494-497. © 2009 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]