MRI-Based Method to Evaluate Engineered Cartilage

描述(申请人提供)：关节软骨对人类腹股沟关节的正常功能至关重要。软骨具有独特的机械和摩擦学特性，通过提供几乎无摩擦和耐磨的承载关节表面来允许运动。骨关节炎是最常见的风湿性疾病，与不同程度的软骨退化和关节力学改变(即对外加载荷的变形)有关。修复和再生因骨关节炎和其他退变过程影响的软骨组织一直是最近新兴的组织工程领域的焦点，组织工程是为受损或病变器官的功能恢复而设计和制造新组织的科学。组织工程学的基础科学研究旨在成功地修复软骨的功能，最终依赖于诱导信号、反应干细胞和细胞外基质支架。 这项研究将(1)开发一种新的非侵入性方法来测量正常和组织工程软骨构建物体积内的不均匀三维(3D)变形；(2)评估牛关节软骨移植修复缺损的效果。在过去的十年中，磁共振成像(MRI)技术或脉冲序列的重大进步已被证明在通过跟踪3D空间中特定组织区域的运动来测量变形方面非常有效。此外，申请者为了完成他的研究生研究，初步开发了一种基于MRI的方法来确定软骨的3D变形。该方法使用定制的MRI脉冲序列、加载装置和图像处理算法来量化整个牛关节软骨移植体积的不均匀机械变形。在这项拟议的研究中，软骨组织区域将通过使用MRI脉冲序列Dante(用于定制激发的延迟和章动交替)和FS-FSE(脂肪抑制的快速自旋回波)来跟踪它们的变形。变形测量将被用来近似正常和组织工程软骨的3D有限应变张量场。

DESCRIPTION (provided by applicant): Articular cartilage is critical to the normal function of human diarthrodial joints. Cartilage has unique mechanical and tribological properties that allows for locomotion by providing a nearly frictionless and wear-resistant load bearing joint surface. Osteoarthritis is the most common rheumatic disease and is associated with various degrees of cartilage degradation and altered joint mechanics (i.e. deformation in response to applied loads). Efforts to repair and regenerate cartilage tissue effected by osteoarthritis and other degenerative processes has been the focus of the recently emerging field of tissue engineering, which is the science of design and manufacture of new tissues for the functional restoration of impaired or diseased organs. Basic science studies in tissue engineering aimed at the successful functional restoration of cartilage ultimately depend on inductive signals, responding stem cells, and extracellular matrix scaffolding. The research proposed here will (1) develop a novel noninvasive method to measure heterogeneous three dimensional (3D) deformations throughout the volume of normal and tissue-engineered cartilage constructs and (2) to evaluate the efficacy of defect repairs in bovine articular cartilage explants. Within the past decade, significant advances in magnetic resonance imaging (MRI) techniques, or pulse sequences, have proven highly effective at measuring deformation by tracking the motion of specific tissue regions in 3D space. Further, the initial development of an MRI-based method to determine 3D deformations in cartilage was developed by the applicant to complete his graduate research. This method quantified heterogeneous mechanical deformations throughout the volume of bovine articular cartilage explants using a custom MRI pulse sequence, loading apparatus, and image processing algorithm. In the proposed research, cartilage tissue regions will be tracked as they deform with the use of the MRI pulse sequences DANTE (delays alternating with nutations for tailored excitation) and FS-FSE (fat-suppressed fast spin echo). The deformation measurements will be used to approximate the 3D finite strain tensor field throughout normal and tissue engineered cartilage.