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: 9325034
• 负责人: Rizwan Ahmad
• 金额: $ 19.25万
• 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 2019-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9325034
• 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; Clinical; 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; tau Proteins

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，肺高血压和先天性心脏病可能会损害 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。在主肺动脉中测得的混合静脉氧气安全是准确的标记 血液和氧的全身递送，可提供关键的诊断和预后价值。但是，是真的 混合静脉安全需要导管进入主肺动脉，并且可能不足为 由于侵入性和风险的相关水平，诊断措施。无创的手段来快速和 准确测量主肺动脉，心脏腔内的O2饱和度（O2SAT），理想情况下 体内任何地方，不仅会减少对侵入性导管程序的需求，而且还会减少 提供可能无法获得或无法获得的重要物理信息。 在血液中，磁共振横向松弛时间（T2）与氧饱和有关 先前已经提出了血红蛋白和MR弛豫计量法以在体内估计血液O2满意度； 但是，这些估计依赖于对每个患者的不切实际的体外校准，结果具有 我们被流动引起的人工制品所破坏。以前在我们的实验室开发的一种技术，用于快速，单发T2 已修改了映射以减少流量伪像并提高流动血液中测得的T2的准确性。 加上这种修改的脉冲序列，我们提出了一种解决LUZ-Meiboom的全新方法 （L-M）描述血液中T2和O2SAT之间关系的方程式。我们假设使用 各种准备脉冲时序以及易于访问的患者特定参数的直接测量 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血液O2SAT的评估，即使在有限的位置， 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仪 通过达到以下特定目标。目标1：我们将定义适当的获取参数限制 和180在流量幻像中，并使用统计灵敏度分析优化采集参数。目标2：我们 将在验证级别低氧血症的猪模型中验证源自T2的O2SAT，该模型能够 目标3：我们将 评估一小部分心力衰竭患者的可行性 混合静脉O2SAT测量的导管插入术。 通过解决T2制备脉冲的流动敏感性和由 对T2与O2SAT相关的模型的简化，我们预计准确性和可重复性水平 对于此技术，将提高心血管疾病患者的临床应用所需的技术。 τ