MICROMAGNETIC RESONANCE ELASTOGRAPHY

微磁共振弹性成像

• 批准号: 6904111
• 负责人: RICHARD L MAGIN
• 金额: $ 21.32万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-03-15 至 2007-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6904111
• 关键词: articular cartilage; bioengineering /biomedical engineering; bioimaging /biomedical imaging; biomedical equipment development; biophysics; cartilage disorder; elasticity; image enhancement; magnetic field; magnetic resonance imaging; mathematical model; microradiography; miniature biomedical equipment; nuclear magnetic resonance spectroscopy; tissue engineering

DESCRIPTION (provided by applicant): Magnetic resonance elastography (MRE) is a phase contrast-based MR imaging technique for observing acoustic strain waves propagating in soft materials (e.g., biological tissues: brain, liver, kidney, muscle, as well as gels, polymers and composites). Mechanical shear waves, typically with amplitudes of less than 100 um and frequencies of 100-500 Hz, are induced using either a piezoelectric or speaker coil oscillator directly coupled to the region of interest. By using multiple phase offsets and motion encoding gradients we acquire data that allows the generation of images that depict shear wave motion and the calculation of local values of the tissue viscoelastic properties. Current MRE studies using 1.5 T MRI systems are directed at establishing techniques for quantifying changes in the mechanical properties of tissues associated with developing disease: malignant tumors appear to be stiffer than benign tumors; fibrosis and cirrhosis tend to increase liver stiffness; and articular cartilage softens in developing osteoarthritis. Work to date suggests that MRE may in fact be able to detect both early stage and diffuse disease well before it can be visualized by conventional MRI, ultrasound or X-ray/CT techniques. Recent MRE investigations are increasingly being conducted at higher spatial resolution to establish histological correlations between elasticity maps and tissue structures; such micro MR elastography (uMRE) studies require stronger static fields, higher performance RF coils and gradients, and more compact, higher frequency mechanical actuators. The goal of the proposed exploratory/development project is to design, develop and validate a new high field (11.74 T) fMRE system (2 cm FOV), 5 kHz maximum acoustic frequency that will provide high spatial resolution (less than 100 fm3 voxel) for the measurement of shear moduli up to 2.5 MPa. These capabilities should allow fMRE to be used to evaluate the microstructure of complex materials, tissues such as articular cartilage and the micromechanical properties of tissue engineered constructs. The specific aims are: 1) Design and build a high resolution fMRE system that operates in the 10 mm diameter clear imaging bore available in an 11.74 T NMR spectrometer (500 MHz for proton); 2) Design, construct and evaluate new mechanical actuators suitable for higher frequency (up to 5 kHz) and multi-frequency shear wave excitation; and 3) Apply fMRE to investigate biological, polymer and composite materials at high spatial resolution.

描述（由申请人提供）：磁共振弹性图（MRE）是一种基于相对比的MR成像技术，用于观察在软材料中传播的声学应变波（例如生物组织：脑，肝脏，肾脏，肌肉，以及凝胶，聚合物，聚合物和复合材料）。使用幅度小于100 UM的振幅，频率为100-500 Hz的机械剪切波是使用压电或扬声器线圈振荡器直接耦合到感兴趣区域的。通过使用多个相位偏移和运动编码梯度，我们获取数据，这些数据允许生成描绘剪切波运动的图像以及组织粘弹性特性的局部值的计算。当前使用1.5 T MRI系统的MRE研究旨在建立技术，用于量化与发育中疾病相关的组织的机械性能变化：恶性肿瘤似乎比良性肿瘤更硬。纤维化和肝硬化倾向于增加肝脏僵硬。关节软骨在发生骨关节炎的过程中会变软。迄今为止的工作表明，MRE实际上可能能够通过常规MRI，超声或X射线/CT技术来表现出早期阶段和弥漫性疾病。最近在较高的空间分辨率上进行了越来越多的MRE研究，以建立弹性图和组织结构之间的组织学相关性。这种微MR弹性图（UMRE）研究需要更强的静态场，更高的性能RF线圈和梯度以及更紧凑的更高频率机械执行器。拟议的探索/开发项目的目的是设计，开发和验证新的高场（11.74 t）FMRE系统（2 cm FOV），5 kHz最大声学频率，该系统将提供高空间分辨率（小于100 fm3 voxel），以测量剪切模量最高2.5 mpa。这些功能应允许FMRE用于评估复杂材料的微观结构，例如关节软骨等组织和组织工程结构的微力特性。具体目的是：1）设计和构建一个高分辨率FMRE系统，该系统以10 mm直径的透明成像孔运行，可在11.74 T NMR光谱仪中使用（质子为500 MHz）； 2）设计，构造和评估适用于高频（最高5 kHz）和多频剪切波激发的新机械执行器； 3）应用FMRE以高空间分辨率研究生物学，聚合物和复合材料。