Diffusion Tensor Imaging of Tendons and Ligaments at Ultra-High Magnetic Fields

Injuries to tendons and ligaments are a common problem limiting daily activities and athletic participation across all age groups. Conventional magnetic resonance imaging (MRI) is reliable for detecting complete tears in tendons and ligaments, but it has difficulty identifying low-grade injuries due to poor contrast and low intensity signal. We describe recent MRI advances using ultra-high magnetic fields and very short time echoes which overcome many of the limitations of the low signal and the short T2 of connective tissues. Using diffusion and relaxometry measurements at 11.7 T, we measured the high field relaxation times, mean diffusivity, and the fractional anisotropy of rabbit semitendinosus tendons and medial collateral ligaments. We found that ultra-high field diffusion tensor imaging and tractography provide repeatable and quantitative maps of fiber organization, which could improve injury diagnosis and therapeutic treatments and assist in presurgical planning.