MRI Biomarkers in Assessing Articular Cartilage Health

磁共振成像(Mri)保持其作为软骨可视化的金标准的地位。 并对软骨组织形态进行全面评价。然而，软骨最早的标志物 变性发生在组织水平，因此不能作为形态变化来检测。在… 目前，还没有有效的方法来客观地、非侵入性地评估软骨健康的这一因素。 缺乏对软骨状况的定量测量阻碍了治疗计划和有意义的 关节损伤的评估。已经提出了许多基于MR的非侵入性显示方法 并量化软骨细胞外基质中这些元素的组成和完整性的变化 (ECM)为蛋白多糖(PG)和体内胶原含量。在已应用于 临床受试者，T2 MRI对涉及软骨退变的几个过程很敏感。延迟 Gd增强的软骨磁共振成像(DGEMRIC)提供了一个与PG最直接相关的指标 内容，但依赖于静脉注射造影剂的选择性摄取。T1rho MRI利用 磁化准备脉冲而无需对比剂管理，以产生参数图，该参数图还 与PG含量密切相关。MRI生化指标的临床解释也仍未得到证实 通过临床或台式核磁共振生物化学研究。还没有研究直接比较核磁共振测量结果 在临床(活体)中对同一组织进行MRI-生化-生物力学测量研究 环境(体外)，为研究结果直接转化为临床解释搭建一座桥梁。这个 这里提出的研究将检验这样的假设，即无创PG敏感MRI与 水/胶原敏感MRI可作为急性损伤后软骨状态的早期诊断手段 在损伤后2年，作为关节和关节健康的客观评价。我们建议SA1) 直接量化PG敏感的体内临床MRI与体外MRI生化指标的一致性 关节软骨的组织化学、生化和生物力学测量 部分；SA2)以展示作为生物标志物的T1RH0/T2松弛序列指标的组合 评估软骨健康和机械功能，SA3)；在损伤时临床应用T1rho/T2MRI作为 作为急性损伤后治疗效果的基准，并作为康复和结果衡量标准。

Magnetic resonance imaging (MRI) maintains its position as the gold standard for visualization of cartilage defects and overall assessment of cartilage morphology. However, the earliest markers of cartilage degeneration occur at the tissue level and are therefore not detectable as changes in morphology. At present, there exists no effective way to objectively assess this element of cartilage health noninvasively. The lack of quantitative measures of cartilage condition hampers treatment planning and meaningful assessment of joint injuries. Numerous MR-based methods have been proposed to noninvasively display and quantitate changes in the composition and integrity of such elements of cartilage extracellular matrix (ECM) as proteoglycan (PG) and collagen content in vivo. Among techniques that have been applied in clinical subjects, T2 MRI is sensitive to several processes involved in cartilage degeneration. Delayed Gadolinium-enhanced MRI of cartilage (dGEMRIC) provides an index that is most directly correlated to PG content, but relies on the selective uptake of intravenously administered contrast agent. T1rho MRI utilizes magnetization preparation pulses without contrast administration, to yield parametric maps that also correlate strongly with PG content. Clinical interpretation of MRI biochemical metrics is still unproven, either by clinical or by benchtop MRI-biochemistry studies. No studies have directly compared MRI measurements in the clinic (in vivo) with MRI-biochemistry-biomechanics measurements on that same tissue in the research environment (ex vivo), to build a bridge for direct translation of research results to clinical interpretation. The research here proposed will test the hypothesis that noninvasive PG-sensitive MRI in combination with water/collagen-sensitive MRI provides an early diagnostic measure of cartilage condition after acute injury and at 2 years post-injury, as an objective evaluation of joint and articular health. We propose SA1) to directly quantify the concordance between PG-sensitive in vivo clinical MRI and ex vivo MRI biochemical metrics with histochemical, biochemical, and biomechanical measurements within articular cartilage sections; SA2) to demonstrate a combination of T1rho/T2 relaxation sequence metrics as a biomarkerto assess cartilage health and mechanical function, SA3); to apply T1rho/T2 MRI clinically at time of injury as a benchmark for acute post-injury treatment effectiveness, and as a rehabilitation and outcomes measure.