Zero Echo Time Imaging of Knee Joint

项目摘要 人类膝关节由许多不同的组织组成，包括关节软骨，钙化软骨， 关节、韧带、肌腱和骨骼，所有这些对关节的健康都很重要。最近的研究 表明骨关节炎（OA）不仅仅是透明软骨的疾病，而是整个关节的疾病。几 研究人员已经证明，T1ρ弛豫时间对蛋白聚糖（PG）含量更敏感， 而T2弛豫时间对胶原蛋白的取向、网络的完整性和 水合作用短T1椎弓根、钙化的软骨、肌腱和韧带是关节的组成部分 这些组织中的生物力学和异常可能影响关节退化和OA的发作。因此，我们认为， 定量评价这些组织中的弛豫时间可以提供早期的敏感的生化标记物， OA诊断和疾病进展。然而，传统的T1ρ-MRI序列（例如，GRE和FSE 读数）在检测半固体短T1ρ组织或组织中的早期大分子变化方面的价值有限 关节、韧带和肌腱等组成部分。大多数膝关节结构，包括膝关节， 韧带和肌腱都具有主要的短（与胶原蛋白和/或胶原蛋白相关的束缚/限制水）， 蛋白聚糖）和次要的长（与大分子结合的较少限制/游离水）组分。 因此，非常需要可靠的、非侵入性的、时间有效的、基于ZTE的双指数3D-T1ρ 用于定量评估膝关节中半固体结构的成像序列， 细胞外基质（ECM）中具有短和长松弛成分的早期生化变化及其 相应的分数。 该R21提案的总体目标是开发、优化和翻译中兴通讯（PETRA）基于 双指数3D-T1ρ成像脉冲序列，用于改善形态学和 膝关节中半固体短T1ρ结构的生物化学表征（膝关节、韧带和 肌腱）上的标准临床3 T扫描仪采用多线圈压缩传感（CS）。

PROJECT SUMMARY Human knee joints are composed of many different tissues including articular cartilage, calcified cartilage, menisci, ligaments, tendons and bone all of which are important for the health of the joint. Recent research suggests that osteoarthritis (OA) is not just a disease of hyaline cartilage, but rather of the entire joint. Several researchers have demonstrated that the T1ρ relaxation time is more sensitive to proteoglycan (PG) content of the cartilage, while T2 relaxation time is more sensitive to collagen orientation, integrity of network and hydration. The short T1ρ menisci, calcified cartilage, tendons, and ligaments are integral part of joint biomechanics and abnormalities in these tissues may impact joint degeneration and onset of OA. Therefore, quantitative evaluation of relaxation times in these tissues may provide sensitive biochemical markers for early OA diagnosis, and disease progression. However, conventional T1ρ-MRI sequences (e.g., GRE and FSE readouts) are limited value in detecting early macromolecular changes in semi-solid short T1ρ tissues or tissue components such as menisci, ligaments and tendons. Most of the knee joint structures, including menisci, ligaments and tendons have both dominant short (bound/restricted water associated with collagen and/or proteoglycans) and minor long (less restricted/free water associated with macromolecules) components. Therefore, there is a significant need for reliable, non-invasive, time efficient, ZTE-based biexponential 3D-T1ρ imaging sequence for quantitative assessment of semi-solid structures in the knee joint that could detect the early biochemical changes in extracellular matrix (ECM) with short and long relaxation components and their corresponding fractions. The overarching goal of this R21 proposal is to develop, optimize, and translate ZTE (PETRA)-based biexponential 3D-T1ρ imaging pulse sequence for improved quantitative assessment of morphological and biochemical characterization of semi-solid short T1ρ structures in the knee joint (menisci, ligaments and tendons) on a standard clinical 3T scanner employing multicoil compressed sensing (CS).