Biophysical Basis of Muscle Functional MRI

肌肉功能 MRI 的生物物理学基础

基本信息

批准号：
7350257
负责人：
BRUCE M. DAMON
金额：
$ 27.78万
依托单位：
VANDERBILT UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-01-10 至 2009-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7350257
关键词：
Accounting Acidosis Affect Alkalosis Amphibia Biochemical Biomechanics Blood Blood Volume Blood capillaries Cell Membrane Permeability Cell Respiration Chemicals Clinical Research Complex Computer Simulation Creatine Kinase Data Dependence Development Diffusion Disease Electric Stimulation Elements Evaluation Event Exercise Exercise stress test Functional Magnetic Resonance Imaging Future Glycolysis Goals Health Human Image Isometric Contraction Joints Kinetics Knowledge Magnetic Resonance Imaging Magnetism Mammals Measures Membrane Metabolic Minor Modeling Muscle Muscle Development Outcome Oxygen Patients Physiological Predisposition Proteins Protocols documentation Protons Rate Reaction Relative (related person)Relaxation Research Personnel Rest Signal Transduction Skeletal Muscle Spinal cord injury Testing Theoretical model Time Tissues Update Variant Water base blood oxygen level dependent capillary falls hemodynamics improved in vivo insight interest magnetic field metabolic abnormality assessment neuromuscular function neuromuscular system practical application programs research study response tool

项目摘要

DESCRIPTION (provided by applicant): Identifying the muscles used in different functional activities and evaluating the metabolic and hemodynamic responses to this activity are essential components of both basic and clinical studies of neuromuscular function. A recent approach to these questions is "muscle functional Magnetic Resonance Imaging" (mfMRI), in which active muscles appear with higher signal intensity (SI) in certain MR images than do inactive muscles. These SI changes result from an increase in the transverse relaxation time constant (T2) of muscle water and a Blood Oxygenation Level Dependent (BOLD) contrast. The physiological events that contribute to these phenomena combine to produce a complex SI time course that is characterized by 1) an initial rise, lasting through the first one or two images; 2) an early dip, extending from the end of the initial rise through the first approximately 60 s; and finally 3) a long-latency increase, which reaches a plateau after about 2 min. We propose that this time course is produced by a complex superposition of metabolic and hemodynamic events, which affect transverse relaxation through mechanisms such as chemical and diffusive exchange and variations in blood magnetic susceptibility. The overall goal of the proposed experiments is therefore to describe quantitatively the biophysical basis of the mfMRI SI time course, with the aim that such an understanding would clarify the relationships between MR imaging and physiological parameters of interest and thereby accelerate the development of mfMRI into practical applications. We will: 1) examine the effects of physiological variables on proton exchange between free intracellular water and intracellular proteins; 2) examine membrane permeability alterations during exercise in vivo; 3) quantify the BOLD effect's contribution to mtMRI SI changes; and 4) develop a comprehensive model that describes quantitatively how physiological and biochemical variables altered during exercise determine mfMRI SI. The outcome of these experiments will be a comprehensive and quantitative description of the physiological and biophysical influences on transverse relaxation in skeletal muscle in vivo, and how experimental variables (such as image type and timing) can be altered to enhance the sensitivity of mfMRI to particular physiological phenomena. Future applications of this knowledge may include studies of metabolic and hemodynamic responses of muscles to exercise in health and disease, the development of improved biomechanical models of functionally relevant multi-joint actions, and the evaluation of functional electrical stimulation protocols for patients with spinal cord injury.

描述（由申请人提供）：确定在不同功能活性中使用的肌肉并评估对该活性的代谢和血液动力学反应是神经肌肉功能的基本和临床研究的重要组成部分。这些问题的最新方法是“肌肉功能磁共振成像”（MFMRI），其中活性肌肉在某些MR图像中以更高的信号强度（SI）出现，而不是非活性肌肉。这些SI的变化是由于肌肉水的横向松弛时间常数（T2）和血液氧合水平（BOLD）对比的增加而导致的。有助于这些现象的生理事件结合在一起，产生复杂的Si时间过程，其特征是1）初始上升，持续到第一个或两个图像； 2）早期倾斜，从初始上升的末端延伸到大约60 s；最后3）长期增加，大约2分钟后达到平稳。我们建议，这种时间过程是由代谢和血液动力学事件的复杂叠加产生的，这些事件通过化学和扩散交换以及血液磁敏感性的变化来影响横向松弛。因此，提出的实验的总体目标是在定量地描述MFMRI SI时间过程的生物物理基础，目的是这样的理解将阐明MR成像与感兴趣的生理学参数之间的关系，从而阐明MFMRI在实际应用中的发展。我们将：1）检查生理变量对游离细胞内水和细胞内蛋白之间质子交换的影响； 2）检查体内运动过程中的膜渗透性改变； 3）量化大胆效应对mtmri si变化的贡献； 4）开发一个综合模型，该模型在锻炼过程中定量描述生理和生化变量如何改变MFMRI SI。这些实验的结果将是对体内骨骼肌横向松弛的生理和生物物理影响的全面和定量描述，以及如何更改实验变量（例如图像类型和时间）以增强MFMRI对特定物理学现象的敏感性。这些知识的未来应用可能包括对肌肉在健康和疾病中运动的代谢和血液动力学反应的研究，改善功能相关的多关节作用的生物力学模型的发展以及对脊髓损伤患者的功能电刺激方案的评估。