Investigation into the effect of spin-lock frequency on the angular dependence of T1rho in in-vivo measurements of femoral knee cartilage at 3T

Given the use of T1rho as a measure of cartilage health and an early indicator for osteoarthritis, it is important to understand the T1rho relaxation mechanism including its somewhat unexplained angular dependence. In the hope of finding a range of spin-lock frequencies (FSLs) with a decreased angular dependence, we generated T1rho maps of in-vivo femoral knee cartilage at various FSLs from 100Hz to 1kHz. We found a visible angular dependence in T1rho measurements for all FSLs including 1kHz. If there exists a range of FSL with little or no angular dependence it is higher than 1kHz.