Enhanced MR for morphological characterization of ligaments, tendons and bone

项目摘要/摘要 根据残疾意识理事会的说法，肌肉骨骼系统和结缔组织的疾病， 在美国，韧带、肌腱和骨骼是导致残疾的头号原因。磁共振成像有 日益成为评估和管理这些疾病的首选诊断工具 以及损伤，因为它不仅可以提供关于解剖结构的信息，而且还可以提供功能方面的信息 非侵入性的。然而，磁共振成像研究人类韧带、肌腱和骨骼的能力受到以下因素的限制 灵敏度不足，对传统磁共振技术的获取缓慢。半固体/固体组织，包括 富含胶原的组织，如钙化的韧带和肌腱，以及骨膜，皮质骨和 小梁骨，由于其非常短的横向(T2)，与传统MRI相比提供的MR信号非常少 放松时间为几毫秒或更短。此外，在漫长的收购时间里，非自愿的 人体受试者的运动引入了运动伪影，这对获得高分辨率的图像构成了关键挑战。 具有诊断价值的分辨率图像。最近开发的几项技术有可能解决 这些限制。超高场7T核磁共振、并行成像和压缩传感显示出独特的 具有灵敏度高、体内获取快等优点。超声在肌肉骨骼成像中的应用研究 短回波时间(UTE)和零回波时间(ZTE)方法已经显示出无与伦比的成像能力 T2物种通常在MRI中是看不见的。然而，这些技术在超高场中的实施是 由于所需的高频多通道线圈阵列的设计困难以及 与超高场相关的问题，例如，磁化率增加、B1不均匀和SAR增加。 在这项研究中，通过协同生物工程研究伙伴关系，我们提出了一个全面的项目 用于在7T下开发高级硬件和成像方法，以实现形态和功能 人体韧带、肌腱和骨骼的特征。这些开发旨在生产高度敏感的、 1例具有临床相关对比的半固体结缔组织的各向同性~100-150微米分辨率图像 分钟扫描时间。硬件开发将包括用于膝盖和四肢的多通道线圈阵列，使用 超材料解耦的正交柔性阵列技术及其在热解中的应用 用于减少磁化率伪影的石墨材料。成像采集的开发将基于 改进的UTE/ZTE序列，并提出了改进的半固态组织的新的集成技术 使用并行成像和压缩传感的对比度、运动校正和加速。我们还将 验证开发的方法并评估性能和安全性/合成孔径雷达。这项研究将提供 用于韧带、肌腱和骨骼的形态和功能表征的灵敏成像工具， 这对于研究半固体结缔组织是非常必要和必要的。我们期待着这项研究 将对肌肉骨骼系统疾病和损伤的管理产生长期的临床影响。

PROJECT SUMMARY/ABSTRACT According to Council for Disability Awareness, diseases of the musculoskeletal system and connective tissue, such as the ligaments, tendons and bone are the #1 cause of disability in the United States. MR imaging has been increasingly becoming the diagnostic tool of choice for evaluation and management of these diseases and injuries due to its potential of providing information on not only anatomic structure but also function noninvasively. However, the capability of MRI in studying human ligaments, tendons and bone is limited by inadequate sensitivity and slow acquisitions of conventional MR technology. Semi-solid/solid tissues, including collagen-rich tissues such as calcified ligaments and tendons, as well as periosteum, cortical bone and trabecular bone, provide very little MR signal with traditional MRI due to their very short transverse (T2) relaxation time of a few milliseconds or less. In addition, during the long acquisition times, involuntary movements of human subjects introduce motion artifacts, posing a critical challenge in obtaining high- resolution images with diagnostic value. Several recently developed technologies have the potential to address these limitations. Ultrahigh field 7T MRI, parallel imaging, and compressed sensing have demonstrated unique advantages of high sensitivity and fast acquisitions in vivo. Studies on musculoskeletal imaging using ultra- short echo time (UTE) and zero echo time (ZTE) methods have shown unparalleled capability to image short T2 species normally invisible in MRI. However, the implementation of these technologies at ultrahigh fields is challenging due to design difficulties of the required high frequency multichannel coil arrays, as well as the problems associated with ultrahigh fields, e.g. increased susceptibility, B1 inhomogeneity, and increased SAR. In this study, through a synergistic bioengineering research partnership, we propose a comprehensive project for developing advanced hardware and imaging methods at 7T to enable morphological and functional characterization of human ligaments, tendons and bone. These developments aim to produce highly sensitive, isotropic ~100-150um resolution images of semi-solid connective tissues with clinically relevant contrast in 1 minute scan time. Hardware developments will include multichannel coil arrays for knee and extremities using quadrature and flexible array technology with metamaterial decoupling, as well as application of pyrolytic graphite materials for reducing susceptibility artifacts. Imaging acquisition developments will be based on improved UTE/ZTE sequences, and we propose new integrated techniques for improved semi-solid tissue contrast, motion correction, and acceleration using parallel imaging and compressed sensing. We will also validate the methods developed and assess the performance and safety/SAR. This research would provide sensitive imaging tools for morphological and functional characterization of ligaments, tendons and bone, which are highly demanded and essential for studying semi-solid connective tissues. We expect this research will have a long-term clinical impact in the management of musculoskeletal system diseases and injuries.