MICROSCOPIC MRI T2 ANISOTROPY IN ARTICULAR CARTILAGE

缺乏非侵入性的标记来检测软骨退化， 阻碍了我们从根本上理解 骨关节炎（OA），以及早期诊断和干预， OA。与常规磁共振成像（MRI）不同， 仅比较软骨图像强度、面积或体积，显微镜MRI （muMRI）非常适合于关节炎的定量研究 软骨muMRI不仅可以产生水的定量图像， 分布，而且还具有反映分子水平的独特参数 组织中的信息。 在最近一项使用自旋-自旋弛豫时间（T2）的muMRI研究中，我们 在14 μ M像素分辨率下定量证明了（1）存在 犬关节软骨中独特的T2各向异性。我们的目标是利用 T2弛豫作为一个敏感的和非侵入性的MRI标记，以研究 关节软骨的组织结构和分子相互作用。我们 提出若干具体目标（1）以确定 在muMRI的T2各向异性和组织学方向之间， 研究T2胶原纤维的异质性 各向异性在不同的承载区域在一个关节;（3）检测 软骨中T2分布曲线的局部各向异性;（4） 为了确定软骨的蛋白多糖成分在 T2各向异性;（5）比较正常软骨的T2特征 与自然受损软骨的;和（6）确定 在加载期间软骨中的区域特异性特征。在 结合起来，这六个目标将产生否则不可用的新的 阐明各种生物物理、生物化学和生物学的信息 在分子水平上， 水平 我们的建议是独一无二的，它结合了muMRI的高分辨率特性， 定量T2测量和组织学信息。的 muMRI技术的完善是我们工作的最大优势。 我们现在可以检查个体组织学中的组织特性， 非侵入性地以显微镜分辨率观察软骨中的区域， 有助于了解并最终预防 关节炎

A lack of non-invasive markers to detect cartilage degradation has prevented a fundamental understanding of the development of osteoarthritis (OA), as well as early diagnosis of and intervention in OA. Unlike convention Magnetic Resonance Imaging (MRI) that measures or compares only cartilage image intensity, area or volume, Microscopic MRI (muMRI) is well-suited for the quantitative study of articular cartilage. The muMRI can produce quantitative images not only of water distribution, but also of unique parameters reflecting molecular level information in the tissue at microscopic resolution. In a recent muMRI study using the spin-spin relaxation time (T2), we demonstrated quantitatively at 14muM pixel resolution that (1) there is a unique T2 anisotropy in canine articular cartilage. Our goal is to use T2 relaxation as a sensitive and non-invasive MRI marker to study the tissue structure and molecular interactions in articular cartilage. We propose a number of specific aims (1) to determine the relationship between the T2 anisotropy by muMRI and the histological orientation of the collagen fibrils; (2) to study the heterogeneity of the T2 anisotropy at different load-bearing areas in a joint; (3) to detect the localized anisotropies of the T2 distribution profile in cartilage; (4) to determine the role of the proteoglycan component of cartilage on the T2 anisotropy; (5) to compare the T2 characteristics of normal cartilage with that of naturally lesioned cartilage; and (6) to determine the zone-specific characteristics in cartilage during loading. In combination, these six aims will yield otherwise unavailable new information to elucidate various biophysical, biochemical and biological mechanisms and properties in this important biomaterial at the molecular level. Our proposal is unique in combining the high-resolution nature of muMRI, the quantitative T2 measurement, and histological information. The perfection of the muMRI techniques is the greatest strength of our work. We can now examine the tissue properties in individual histological zones in cartilage non-invasively and at microscopic resolution, thus contributing to the understanding, and ultimately, prevention of arthritic disease.