Combined T1-T2 mapping of human femoro-tibial cartilage with turbo-mixed imaging at 1.5T

Abstract

Purpose: To evaluate the influence of Gd-DTPA on cartilage T2 mapping using turbo-mixed (tMIX) imaging, and to show the possible usefulness of the tMIX technique for simultaneously acquiring T1 and T2 Information in cartilage. Materials and Methods: Twenty volunteers underwent MRI of the knee using the tMIX sequence before and after gadolinium administration, T1 and T2 maps were calculated. The mean T1 was determined on the pre- and post-contrast T1 maps. T2 relaxation values before and after gadolinium administration were statistically analyzed. Results: The obtained relaxation values are in correspondence with previously published data. The mean T1 before gadolinium administration was 449 msec ± 34.2 msec (SD), and after gadolinium administration it was 357 msec ± 55.8 msec (SD), The postcontrast T1 relaxation range was 221.5-572.8 msec. The mean T2 of the precontrast T2 maps was 34.2 msec ± 3.1 msec (SD), and the mean T2 of the postcontrast T2 maps was 32.5 msec ± 3.1 msec (SD), These are statistically significant different values. A correction for the postcontrast T2 values, using a back-calculation algorithm, yielded a 98% correlation with the precontrast T2 values. Conclusion: The absolute difference of pre- and postcontrast T2 is very small and is ruled out using the back-calculation algorithm. Combined T1-T2 tMIX cartilage mapping is a valuable alternative for separate T1 and T2 cartilage mapping. © 2005 Wiley-Liss, Inc.