3D adiabatic T_1ρ prepared ultrashort echo time cones sequence for whole knee imaging

To develop a 3D adiabatic T_1ρ prepared ultrashort echo time cones (3D AdiabT_1ρ UTE-Cones) sequence for whole knee imaging on a clinical 3T scanner.

A train of adiabatic full passage pulses were used for spin locking, followed by time-efficient multispoke UTE acquisition to detect signals from both short and long T₂ tissues in the whole knee joint. A modified signal model was proposed for multispoke UTE data fitting. The feasibility of this 3D AdiabT_1ρ UTE-Cones technique was demonstrated through numerical simulation, phantom, and ex vivo knee sample studies. The 3D AdiabT_1ρ UTE-Cones technique was then applied to 6 in vivo knee joints of healthy volunteers to measure T_1ρ values of quadriceps tendon, patellar tendon, anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), meniscus, patellar cartilage, and muscle.

Numerical simulation, phantom and ex vivo knee sample studies demonstrated the feasibility of whole knee imaging using the proposed multispoke 3D AdiabT_1ρ UTE-Cones sequence. The healthy volunteer knee study demonstrated an averaged T_1ρ of 13.9 ± 0.7 ms for the quadriceps tendon, 9.7 ± 0.8 ms for the patellar tendon, 34.9 ± 2.8 ms for the ACL, 21.6 ± 1.4 ms for the PCL, 22.5 ± 1.9 ms for the meniscus, 44.5 ± 2.4 ms for the patellar cartilage, and 43.2 ± 1.1 ms for the muscle.

The 3D AdiabT_1ρ UTE-Cones sequence allows volumetric T_1ρ assessment of both short and long T₂ tissues in the knee joint on a clinical 3T scanner.