To evaluate if the difference between pre- and post-Gd-DTPA(2-) relaxation rate (DeltaR(1)) 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)).
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 T(1) mapping. Effect sizes for T(1pre), T(1Gd), and DeltaR(1) 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.
T(1Gd) and DeltaR(1) 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 DeltaR(1) vs. T(1Gd) (R = 0.96).
Either T(1Gd) or DeltaR(1) 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 T(1) measurements, our data further support the continued use of T(1Gd) as the dGEMRIC index in the evaluation of native cartilage.