  T1rho imaging is a promising non-invasive diagnostic tool for early detection
of articular cartilage degeneration. A mono-exponential model is normally used
to describe the T1rho relaxation process. However, mono-exponentials may not
adequately to describe NMR relaxation in complex, heterogeneous, and
anisotropic materials, such as articular cartilage. Fractional-order models
have been used successfully to describe complex relaxation phenomena in the
laboratory frame in cartilage matrix components. In this paper, we develop a
time-fractional order (T-FACT) model for T1rho fitting in human articular
cartilage. Representative results demonstrate that the proposed method is able
to fit the experimental data with smaller root mean squared error than the one
from conventional mono-exponential relaxation model in human articular
cartilage.
