Enhanced MR for morphological characterization of ligaments, tendons and bone

项目概要/摘要 据残疾意识理事会称，肌肉骨骼系统和结缔组织疾病， 例如韧带、肌腱和骨骼是美国残疾的头号原因。MR成像具有 越来越成为评价和管理这些疾病的首选诊断工具 由于其不仅可以提供解剖结构信息，还可以提供功能信息， 非侵入性地。然而，MRI在研究人类韧带、肌腱和骨骼方面的能力受到以下因素的限制： 灵敏度不足和常规MR技术采集缓慢。半固体/固体组织，包括 富含胶原蛋白的组织，如钙化的韧带和肌腱，以及骨膜、皮质骨和 骨小梁，由于其非常短的横截（T2），传统MRI提供的MR信号非常少 此外，在长的采集时间期间，不自主的弛豫时间为几毫秒或更短。 人类主体的运动引入了运动伪影，这对获得高- 分辨率图像具有诊断价值。最近开发的几项技术有可能解决 这些限制。超高场7 T MRI、并行成像和压缩感知已经证明了其独特的 具有灵敏度高、体内采集速度快等优点。应用超声波进行肌肉骨骼成像的研究 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短回波的能力 T2物质在MRI中通常不可见。然而，这些技术的实施在Escherichfields是 由于所需的高频多通道线圈阵列的设计困难，以及 与电磁场相关的问题，例如，敏感性增加、B1不均匀性和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 用于开发先进的硬件和7 T成像方法， 人体韧带、肌腱和骨骼的表征。这些发展旨在生产高度敏感， 半固体结缔组织的各向同性~100- 150 um分辨率图像，具有临床相关对比度， 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， 正交和灵活的阵列技术与超材料去耦，以及应用热解 石墨材料，用于减少磁化率伪影。成像采集的发展将基于 改进的UTE/ZTE序列，我们提出了新的集成技术，改善半固体组织 使用并行成像和压缩感测的对比度、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/SAR。这项研究将提供 用于韧带、肌腱和骨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来说是非常需要和必需的。我们希望这项研究 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.