MRI Susceptometry for Measuring Hemoglobin Saturation In Vivo

用于测量体内血红蛋白饱和度的 MRI 敏感度测定法

• 批准号: 7471852
• 负责人: Felix W Wehrli
• 金额: $ 23.63万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-05-01 至 2010-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7471852
• 关键词: Address; Arteries; Blood; Blood Circulation; Blood Gas Analysis; Blood Volume; Brain; Caliber; Calibration; Cardiopulmonary Bypass; Chronic Obstructive Airway Disease; Clinical; Condition; Congenital Heart Defects; Depth; Development; Diabetes Mellitus; Disease; Equation; Error Sources; Erythrocytes; Forearm; Hematocrit procedure; Hemodilution; Hemoglobin; Human; Human Volunteers; Hypoxemia; Image; Individual; Ischemia; Kidney; Laboratories; Length; Limb structure; Liver; Magnetic Resonance; Magnetic Resonance Imaging; Magnetism; Maps; Measurement; Measures; Methodology; Methods; Modeling; Near-Infrared Spectroscopy; Noise; Numbers; Optics; Organ; Oxygen; Oxygen saturation measurement; Peripheral; Peripheral Vascular Diseases; Phase; Physiologic pulse; Physiological; Predisposition; Process; Protons; Public Health; Pulse taking; Pump; Radiation; Rate; Relative (related person); Relaxation; Reproducibility; Research; Resolution; Rest; Shapes; Signal Transduction; Solutions; Source; Stimulus; Structure of popliteal artery; Techniques; Technology; Testing; Time; Tissues; Traction; Training; Tweens; Validation; Variant; Veins; Venous; Water; Whole Blood; Work; base; deoxyhemoglobin; design; human subject; in vivo; magnetic field; response; tissue oxygenation; transmission process; water diffusion

DESCRIPTION (provided by applicant): Changes in blood oxygen saturation are of pivotal importance in a multitude of clinical conditions, including peripheral vascular disease, congenital cardiac abnormalities, diabetes, hypoxemias such as in chronic obstructive pulmonary disease, and ischemic disease of various organs. Current noninvasive methods are based on near infrared spectroscopy (NIRS) which can measure tissue oxygen saturation. These methods, however, are hampered by poor resolution. Further, the relative opacity of mammalian tissue to optical radiation precludes measurements of deep-lying tissues, and the method is unable to target specific arteries and veins. Quantitative MRI resting on a measurement of blood T2 has proven useful but the method requires extensive calibration and its implementation is involved. In this project we propose the development, implementation and validation of a new method for measuring blood oxygen saturation that involves virtually no calibration, allows for rapid and reliable measurement of hemoglobin saturation in arteries and veins at high spatial resolution. The method's principle is based on a measurement of the bulk magnetic susceptibility of blood, which is a function of the blood's hemoglobin oxygen saturation. In a vessel that can be modeled as a cylinder whose diameter is much less than its length, the demagnetizing field has a simple closed-form solution. From the intra-to-extravascular induced magnetic field difference obtained by phase mapping, the blood's volume susceptibility can be computed and thus hemoglobin saturation obtained. We show in preliminary work the method's feasibility and demonstrate its ability to quantify the response to a physiologic stimulus in the peripheral circulation. In four specific aims we propose to further develop and evaluate the image acquisition and processing methodology and quantify potential sources of error, both computationally and experimentally. We plan to validate the method in human subjects in models of peripheral limb ischemia and compare the baseline and post-occlusion hyperemic response with those of blood gas analysis as well as with tissue oxygen saturation measured by NIRS. PUBLIC HEALTH RELEVANCE: Venous and arterial oxygen saturation are among the most important physiological parameters. Currently, there exist no robust noninvasive techniques for measuring hemoglobin saturation in individual deep-lying vessels. Magnetic resonance susceptometry has substantial promise to fill this gap.

描述（由申请人提供）：血氧饱和度的变化在多种临床病症中至关重要，包括外周血管疾病、先天性心脏异常、糖尿病、慢性阻塞性肺病等低氧血症以及各种器官的缺血性疾病。目前的无创方法基于近红外光谱 (NIRS)，可以测量组织氧饱和度。然而，这些方法因分辨率差而受到阻碍。此外，哺乳动物组织对光辐射的相对不透明度阻碍了对深层组织的测量，并且该方法无法针对特定的动脉和静脉。基于血液 T2 测量的定量 MRI 已被证明是有用的，但该方法需要大量校准并且涉及其实施。在这个项目中，我们建议开发、实施和验证一种测量血氧饱和度的新方法，该方法几乎不需要校准，可以以高空间分辨率快速可靠地测量动脉和静脉中的血红蛋白饱和度。该方法的原理基于对血液整体磁化率的测量，该磁化率是血液血红蛋白氧饱和度的函数。在可以建模为直径远小于其长度的圆柱体的容器中，退磁场具有简单的封闭式解。根据相位映射获得的血管内外感应磁场差，可以计算出血液体积的磁化率，从而获得血红蛋白饱和度。我们在初步工作中展示了该方法的可行性，并证明了其量化外周循环中生理刺激反应的能力。在四个具体目标中，我们建议进一步开发和评估图像采集和处理方法，并通过计算和实验量化潜在的误差源。我们计划在人类受试者的周围肢体缺血模型中验证该方法，并将基线和闭塞后充血反应与血气分析以及 NIRS 测量的组织氧饱和度进行比较。公共卫生相关性：静脉和动脉氧饱和度是最重要的生理参数之一。目前，还没有强大的非侵入性技术来测量单个深层血管中的血红蛋白饱和度。磁共振敏感度测定法有望填补这一空白。