MRI T2 mapping for quantitative assessment of venous oxygen saturation

用于定量评估静脉血氧饱和度的 MRI T2 映射

• 批准号: 9182512
• 负责人: Rizwan Ahmad
• 金额: $ 23.1万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-02 至 2018-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9182512
• 关键词: Address; Americas; Blood; Blood Gas Analysis; Blood flow; Calibration; Cardiac; Cardiac Catheterization Procedures; Cardiac Output; Cardiovascular Diseases; Cardiovascular system; Catheterization; Catheters; Cause of Death; Congenital Heart Defects; Coronary sinus structure; Data; Diagnostic; Diagnostic Procedure; Equation; Estimation Techniques; Family suidae; Generic Drugs; Health; Heart; Heart failure; Hematocrit procedure; Hemoglobin; Hypoxemia; In Vitro; Ischemia; Limb structure; Location; Magnetic Resonance; Magnetic Resonance Imaging; Maps; Measurement; Measures; Metabolic; Methodology; Modeling; Morphologic artifacts; Myocardial; Oxygen; Oxygen saturation measurement; Patients; Physiologic pulse; Physiological; Population; Preparation; Procedures; Pulmonary Artery Catheterization; Pulmonary Hypertension; Pulmonary artery structure; Relaxation; Reproducibility; Risk; Signal Transduction; Statistical sensitivity; Techniques; Time; Tissues; Venous; base; body system; clinical application; clinically relevant; cohort; congenital heart disorder; improved; in vivo; individual patient; meetings; novel strategies; prevent; prognostic value; success

Heart failure, pulmonary hypertension, and congenital heart disease can compromise the capacity of the cardiovascular system to deliver sufficient oxygen (O2) to meet the varying metabolic demands of the organ systems. Mixed venous oxygen saturation measured in the main pulmonary artery is an accurate marker of the systemic delivery of blood and oxygen that provides key diagnostic and prognostic value. However, a true mixed venous saturation requires catheter access to the main pulmonary artery and may be underutilized as a diagnostic measure due to the associated level of invasiveness and risk. A non-invasive means to quickly and accurately measure O2 saturation (O2sat) in the main pulmonary artery, the cardiac chambers, and ideally anywhere in the body, would not only reduce the need for invasive catheterization procedures, but would also provide important physiological information that may be otherwise unavailable or unobtainable. In the blood, the magnetic resonance transverse relaxation time (T2) is related to the oxygen saturation of hemoglobin, and MR relaxometry has been previously proposed for in vivo estimation of blood O2 saturation; however, these estimates have relied on an impractical in vitro calibration on each patient, and results have been corrupted by flow-induced artifacts. A technique previously developed in our lab for rapid, single-shot T2 mapping has been modified to reduce flow artifacts and improve the accuracy of T2 measured in flowing blood. Together with this modified pulse sequence, we propose an entirely new approach to solving the Luz-Meiboom (L-M) equation that describes the relationship between T2 and O2sat in blood. We hypothesize that the use of varied preparation pulse timing along with direct measurement of easily accessible patient specific parameters will support the application of non-linear parameter estimation techniques to provide an accurate quantitative assessment of blood O2sat in the heart and deep vessels, even in locations having limited accessibility with other diagnostic techniques. We propose to optimize and validate this approach to non-invasive blood oximetry by meeting the following specific aims. Aim 1: We will define appropriate limits for acquisition parameters TE and 180 in a flow phantom and optimize acquisition parameters using statistical sensitivity analysis. Aim 2: We will empirically validate O2sat derived from T2 in a porcine model of graded hypoxemia that enables simultaneous acquisition of T2 and invasive O2sat measurement over a broad range of values. Aim 3: We will evaluate feasibility in a small cohort of heart failure patients undergoing clinically indicated pulmonary artery catheterization for mixed venous O2sat measurement. By addressing the flow sensitivity of the T2 preparation pulse and the inaccuracies introduced by oversimplification of the model relating T2 to O2sat, we anticipate that the level of accuracy and reproducibility for this technique will be raised to that required for clinical application in patients with cardiovascular disease. τ

心力衰竭、肺动脉高压和先天性心脏病会损害心脏的功能， 心血管系统提供足够的氧气（O2），以满足器官的不同代谢需求 系统.在主肺动脉中测量的混合静脉血氧饱和度是肺动脉高压的准确标志。 全身输送血液和氧气，提供关键的诊断和预后价值。然而，一个真正的 混合静脉饱和需要导管进入主肺动脉， 诊断措施，由于相关的侵入性和风险水平。一种非侵入性的方法， 准确测量主肺动脉、心腔中的氧饱和度（O2 sat）， 在身体的任何地方，不仅可以减少对侵入性导管插入术的需要，而且还可以 提供了重要的生理信息，否则这些信息可能无法获得或无法获得。 在血液中，磁共振横向弛豫时间（T2）与血液中的氧饱和度有关。 血红蛋白，并且MR弛豫测定法先前已经被提出用于血液O2饱和度的体内估计; 然而，这些估计依赖于对每个患者的不切实际的体外校准，并且结果 被流动引起的伪影破坏了我们实验室以前开发的快速单次T2成像技术 已经修改了映射以减少流动伪影并提高在流动血液中测量的T2的准确性。 与此修改后的脉冲序列，我们提出了一个全新的方法来解决Luz-Meiboom (L-M)描述血液中T2和O2 sat之间关系的方程。我们假设使用 不同的准备脉冲定时沿着直接测量易于获取的患者特定参数 将支持非线性参数估计技术的应用，以提供准确的定量 评估心脏和深血管中的血氧饱和度，即使在使用 其他诊断技术。我们建议优化和验证这种方法的非侵入性血氧饱和度 实现以下具体目标。目标1：我们将定义采集参数TE的适当限值 和180，并使用统计灵敏度分析优化采集参数。目标2：我们 将在分级低氧血症的猪模型中根据经验验证来自T2的O2 sat， 在广泛的数值范围内同时采集T2和侵入性O2 sat测量。目标3：我们 评估在接受临床指征肺动脉栓塞的心力衰竭患者小队列中的可行性 混合静脉血氧饱和度测量导管插入术。 通过解决T2准备脉冲的流量灵敏度和由T2准备脉冲引入的不准确性， 由于T2与O2 sat相关模型过于简化，我们预计准确性和再现性水平 因为这项技术将提高到临床应用于心血管疾病患者所需的水平。 τ