Optimizing MR signal contrast of the temporomandibular joint disk.

ABSTRACT

PURPOSE: To use a tissue specific algorithm to numerically optimize UTE sequence parameters to maximize contrast within temporomandibular joint (TMJ) donor tissue. MATERIALS AND METHODS: A TMJ specimen tissue block was sectioned in a true sagittal plane and imaged at 3 Tesla (T) using UTE pulse sequences with dual echo subtraction. The MR tissue properties (PD, T(2) , T(2) *, and T(1) ) were measured and subsequently used to calculate the optimum sequences parameters (repetition time [TR], echo time [TE], and θ). RESULTS: It was found that the main contrast available in the TMJ could be obtained from T(2) (or T(2) *) contrast. With the first echo time fixed at 8 µs and using TR = 200 ms, the optimum parameters were found to be θ ≈ 60°, and TE2 ≈ 15 ms, when the second echo is acquired using a gradient echo and θ ≈ 120°, and TE2 ≈ 15 ms, when the second echo is acquired using a spin echo. CONCLUSION: Our results show that MR signal contrast can be optimized between tissues in a systematic manner. The MR contrast within the TMJ was successfully optimized with facile delineation between disc and soft tissues.