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

描述（由申请人提供）：颞下颌紊乱（TMDs）是导致疼痛和残疾的第二常见肌肉骨骼疾病，结合了骨科原理和疼痛的生物心理社会模型。TMJ具有复杂的解剖结构，主要由纤维软骨组成，在MRI上表现为短T2组织（固有MR特性）。临床影像学问题和背景：标准的临床MRI序列将这些组织描绘为信号空洞（黑色），使其难以视觉表征和定量评估。我们已经实现了高分辨率的短TE序列，并开发了一种新的3D 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UTE技术（允许从TMJ椎间盘，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毫秒范围内（如我们初步研究确定的TMJ组织）的短T2值（反映胶原取向和完整性）。utt1 rho序列是一种定量MR技术，旨在评估短T2组织中的蛋白多糖完整性。假设:我们假设，我们的前瞻性随机研究将表明，与现有的专为长T2组织设计的技术相比，我们针对短T2组织评估的新型3T短TE和UTE MRI技术将1)在体外定性评估时提供更准确的形态学和结构数据，包括骨变化；2)作为生化和生物力学改变以及退变的更敏感的生物标志物。在体外定量评估时，3)与体内临床评估评分提供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分级的准确性与为长T2组织量身定制的准确性。在第二部分，我们将比较UTE MRI技术（短T2和T1rho值）和专为长T2组织（长T2和T1rho值）确定的定量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的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）序列，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，因为它使用了新开发的MR脉冲序列，提出了组织的形态和生化评估，并提出了针对特定组织定制MRI参数的新概念，并探索了定量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.