Three-dimensional Ultrashort Echo Time Magnetic Resonance Imaging of Entheses

7.摘要 末端是肌腱、韧带和关节囊与骨骼相连的区域。他们是 柔性组织和刚性组织之间的过渡区，应力集中在两者之间的连接处 不同类型的组织，因为它们的机械性能有很大的差异。Enters非常常见地涉及到 在许多疾病中，包括过度使用综合征、早期骨关节炎(OA)和银屑病 关节病(PSA)。尽管终端炎很重要，但评估它是困难的。临床考试的依据是 直接触诊的压痛可能不敏感，也不特异。超声波可以显示鼻腔异常， 而是依赖于运算符。常规磁共振成像在显示关键组织方面没有帮助。 存在于T2*S较短且信号很少或没有信号的正常肠腔中。结果是正规型括号 与临床磁共振成像不能识别。此外，临床磁共振成像生物标记物如T2(A) 胶原生物标记物)和T1(蛋白多糖或PG的生物标记物)显示出很强的魔角效应， 可能导致T2和T1在组织纤维定向到B0场的~55时增加数倍。 我们研制了3D超短回波时间(UTE)序列，其TES为8微米，S为100~1000倍 比临床序列的TES更短，使我们能够成像。最近的研究表明，绝热 自旋锁定和磁化转移(MT)成像是魔角不敏感的。UTE的组合 绝热T1可用于魔角不敏感的PG变化评估。组合在一起 UTE和MT可以提供对水和胶原质子组分的魔角不敏感的评估和 以括号表示的汇率。UTE-绝热-T1和UTE-MT都需要T1补偿。UTE With Actual 翻转角度成像(AFI)可以准确地定位短T2组织的T1。我们的中心假设是 利用UTE序列直接成像和量化末端的能力将为关联提供新的选择 具有机械功能的结构，是识别疾病变化的重要方法。我们的目标 是使用UTE对PSA患者的肌腱和肌腱进行系统和全面的表征。在……里面 目的1我们将建立评估肌腱和肌腱中PG、胶原和水成分的UTE序列。 正常踝关节(n=10)。在目标2中，我们将比较UTE和临床序列 评价踝关节标本无异常(n=20)，并建立良好的PSA(n=20)。我们将相互关联 MRI测量包括组织病理学、PLM、生物化学和生物力学。在目标3中，我们将应用UTE 正常对照组(n=30)和无临床症状的PSA患者的跟腱连接序列 神经末端炎和活动性神经末端炎各30例。PSA患者将接受肿瘤坏死因子治疗 (肿瘤坏死因子)抑制剂，并将在2个月、6个月和12个月再次扫描，以了解纵向变化。我们会 将磁共振测量结果与体检和患者报告的结果(PRO)相关联。我们期待着 UTE MRI测量将与PROS、末端炎症和亚临床末端炎症高度相关。

7. Abstract Entheses are regions where tendons, ligaments and joint capsules are connected to bone. They are transition zones between flexible and rigid tissues, and stress concentrates at the junction between these two types of tissue as a result of their widely different mechanical properties. Entheses are very commonly involved in many diseases including the overuse syndromes, the early stages of osteoarthritis (OA) and psoriatic arthropathy (PsA). Despite its importance, assessment of enthesitis is difficult. Clinical exam based on tenderness on direct palpation may not be sensitive nor specific. Ultrasound can show enthesial abnormalities, but is operator dependent. Conventional MR imaging has not been helpful in demonstrating the key tissues present in normal entheses which have short T2*s and show little or no signal. As a result normal entheses have not been identifiable with clinical MR imaging. Furthermore, clinical MR imaging biomarkers like T2 (a biomarker of collagen) and T1 (a biomarker of proteoglycan or PG) show strong magic angle effects, which may result in a several fold increase in T2 and T1 when the tissue fibers are oriented ~55 to the B0 field. We have developed 3D ultrashort echo time (UTE) sequences with TEs of 8 µs that are 100~1000 times shorter than the TEs of clinical sequences, allowing us to image entheses. Recent studies show that adiabatic spin-locking and magnetization transfer (MT) imaging are magic angle insensitive. The combination of UTE and adiabatic T1 may allow magic angle insensitive assessment of PG changes in entheses. The combination of UTE and MT may provide magic angle insensitive evaluation of water and collagen proton fractions and exchange rates in entheses. Both UTE-adiabatic-T1 and UTE-MT require T1 compensation. UTE with actual flip angle imaging (AFI) allows accurate T1 mapping of short T2 tissues. Our central hypothesis is that the ability to directly image and quantify the entheses with UTE sequences will provide a new option for correlating structure with mechanical function, and an important method for recognizing change in disease. Our objective is to use UTE for systematic and comprehensive characterization of tendons and entheses in PsA patients. In Aim 1 we will develop UTE sequences for assessment of PG, collagen and water components in tendons and entheses in normal ankles (n=10). In Aim 2 we will compare UTE and clinical sequences for quantitative evaluation of ankle specimens with no abnormality (n=20), and well established PsA (n=20). We will correlate MRI measures with histopathology, PLM, biochemistry and biomechanics. In Aim 3 we will apply UTE sequences to the Achilles tendon enthesis in normal controls (n=30), PsA patients with no clinically evident enthesitis (n=30) and with active enthesitis (n=30). The PsA patients will be treated with tumor necrosis factor (TNF) inhibitors, and will be scanned again at two, six and 12 months to access longitudinal changes. We will correlate the MR measures with physical examination and patient reported outcomes (PROs). We expect that UTE MRI measures will be highly correlated with PROs, enthesial inflammation and subclinical enthesitis.