Novel 3T MRI of TMJ Using Short and Ultrashort Echo Time (UTE) Techniques

描述（由申请人提供）：颞下颌关节紊乱病（TMD）是导致疼痛和残疾的第二大常见肌肉骨骼疾病，结合了骨科原理和疼痛的生物心理社会模型。颞下颌关节具有复杂的解剖结构，主要由纤维软骨成分组成，在MRI上被表征为短T2组织（固有MR特性）。临床成像问题和背景：标准临床MRI序列将这些组织描绘为信号空白（黑色），使其难以视觉表征和定量评价。我们已经实现了高分辨率短TE序列，并开发了一种新的三维UTE技术，旨在最佳地表征TMJ组织。我们还开发了新的定量MR序列，将联合收割机UTE技术（允许从TMJ盘、纤维软骨、髁突软骨下骨采集信号）与T2和T1 rho应用相结合。UTE T2准备序列是一种混合定量MR技术，旨在准确评估2至10 msec范围内的短T2值（反映胶原蛋白方向和完整性）（如我们的初步研究确定的TMJ组织）。UTE T1 rho序列是一种定量MR技术，旨在评价短T2组织中蛋白聚糖的完整性。假设：我们假设我们的前瞻性随机研究将表明，与针对长T2组织定制的现有技术相比，我们针对TMJ髁突纤维软骨和椎间盘的短T2组织评估定制的新型3T短TE和UTE MRI技术将1）提供更准确的形态和结构数据，包括体外定性评估时的骨变化，2）当在体外定量评估时，作为生物化学和生物力学改变以及变性的更敏感的生物标志物，和3）提供与体内临床评估评分更强的定性和定量相关性。我们建议通过三个目标来解决这个问题。首先，我们将比较基于高分辨率2D短TE和新开发的3D UTE技术的形态学MR分级与针对长T2组织定制的MR分级的准确性。在第二部分中，我们将比较从UTE MRI技术（短T2和T1rho值）确定的定量MR特性与从针对长T2组织（长T2和T1rho值）定制的技术获得的定量MR特性对生化和生物力学改变以及组织病理学的敏感性。在第三项研究中，我们将在无症状志愿者和有症状患者中实施新型3T UTE MRI高分辨率形态学、3D UTE和定量UTE MR序列（2D T2*、UTE T2 Prep和UTE T1 rho），并将结果与临床评估评分系统相关联。创新：我们的研究是创新的，因为它使用新开发的MR脉冲序列，提出了组织的形态学和生物化学评价，并提出了新的概念，定制MRI参数，以特定的组织，并探索定量MR技术作为组织功能的生物标志物。

DESCRIPTION (provided by applicant): Temporomandibular disorders (TMDs) represent the second most commonly occurring musculoskeletal condition resulting in pain and disability, combining orthopedic principles with biopsychosocial models of pain. The TMJ has complex anatomy comprised largely of fibrocartilaginous components that on MRI are characterized as short T2 tissues (intrinsic MR property). Clinical Imaging Problem and Background: Standard clinical MRI sequences portray these tissues as signal void (black), making them difficult to visually characterize and to quantitatively evaluate. We have implemented high resolution short TE sequences and developed a new 3D UTE technique that was designed to optimally characterize the TMJ tissues. We have also developed novel quantitative MR sequences that combine UTE technique (to allow signal acquisition from TMJ disc, fibrocartilage, condylar subchondral bone) with T2 and T1 rho applications. The UTE T2 prep sequence is a hybrid quantitative MR technique designed to accurately evaluate short T2 values (reflecting collagen orientation and integrity) in the 2 to 10 msec range (as in TMJ tissues determined by our preliminary studies). The UTE T1 rho sequence is a quantitative MR technique that was designed to evaluate proteoglycan integrity in short T2 tissues. Hypothesis: We hypothesize that our prospective, randomized study will show that our novel 3T short TE and UTE MRI techniques tailored for short T2 tissue evaluation of TMJ condylar fibrocartilage and disc, compared to existing techniques tailored for long T2 tissues, will 1) provide more accurate morphologic and structural data including bony changes when evaluated qualitatively in vitro, 2) serve as more sensitive biomarkers of biochemical and biomechanical alterations, as well as degeneration, when evaluated quantitatively in vitro, and 3) offer stronger qualitative and quantitative correlates to in vivo clinical assessment scores. We propose to address this through 3 aims. In the first, we will compare the accuracy of morphologic MR grading based on high resolution 2D short TE and newly developed 3D UTE techniques to those tailored for long T2 tissues. In the second, we will compare sensitivity of quantitative MR properties determined from UTE MRI techniques (short T2 and T1rho values) to those obtained from techniques tailored for long T2 tissues (long T2 and T1rho values) to biochemical and biomechanical alterations, as well as histopathology. In the third we will implement novel 3T UTE MRI high resolution morphologic, 3D UTE, and quantitative UTE MR sequences (2D T2*, UTE T2 Prep and UTE T1 rho) sequences in asymptomatic volunteers and symptomatic patients and correlate findings with a clinical assessment scoring system. Innovation: Our study is innovative in that it uses newly developed MR pulse sequences that propose both morphologic and biochemical evaluation of tissue, and presents new concepts regarding tailoring MRI parameters to specific tissues, and exploring quantitative MR techniques as a biomarker for tissue function.