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 y).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 ms and using TR ¼ 200 ms, the optimum parameters were found to be: y % 60 , and TE2 % 15 ms, when the second echo is acquired using a gradient echo and y % 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.

High-resolution morphologic and ultrashort time-to-echo quantitative magnetic resonance imaging of the temporomandibular joint

“…The MR properties of the tissue will reflect the structural changes; therefore quantification of those properties is essential to recognize early alterations. As any fibrocartilaginous structure, the articular disc has short T2 components that cannot be evaluated with the standard MR techniques [13–15,31–33], that is why the application of UTE techniques is especially useful in the evaluation of the articular disc and other structures with short T2 components in the TMJ.…”

“…In the TMJ some tissues such as the cortical bone and the fibrocartilage present in the disc and in the articulating surfaces, have a majority of short T2 components [12–14]. As conventional MRI sequences use longer TEs, signal from those short T2 tissues has decayed before imaging acquisition [13–15]. …”

“…Recently implemented ultrashort time-to-echo (UTE) pulse sequences, which use much shorter TEs (down to 8 μs) as compared with conventional MRI, allow the detection of signal from tissues with short T2 components [13–15]. Quantitative MRI using UTE pulse sequences facilitate the evaluation of such tissues [26–30].…”

UTE MRI of the Osteochondral Junction

“…2d, 4d). For this technique, short T2 contrast can be modulated by varying TEs, usually the later TE [33]. A variation of this technique, such as rescaled or weighted digital subtraction [34, 35], is also available.…”

4D ultra-short TE (UTE) phase-contrast MRI for assessing stenotic flow and hemodynamics.

“…This technique has been used for several clinical applications such as cortical bone [129][130][131], Tendons and ligaments [132,133], Atherosclerotic Plaque [134][135][136], knee [129,[137][138][139], Articular cartilage [140][141][142][143][144], spine [145], temporomandibular joint (TMJ) disk [146], liver [147,148] and neuroimaging in brain and central nervous system [149,150]. Recently, a 2-D phase-contrast MR sequence was presented based on the ultra-short TE (UTE) technique with TE reduced to 0.65 msec [12].…”