Quantitation of Lung Ventilation and Structure by 3He MR

超出所提供的空间。 肺气肿是美国和世界范围内的一个主要医疗问题。评估肺气肿的诊断方法应该对肺泡水平的局部肺结构敏感。超极化3He气体扩散MRI评估3He气体ADC（表观扩散系数）可以提供这种灵敏度。它提供了传统成像模式和肺功能测试无法提供的肺微观结构和功能信息。使用3He扩散MRI，可以评估肺泡大小和肺泡壁的完整性，即使肺泡太小而不能通过直接成像来分辨。这表明超极化3He气体ADC测量的临床应用潜力很大。然而，直到最近还不清楚3He气体ADC测量探测肺结构的具体特征。最近，我们提出了一个理论模型的基础上，大量的组织学数据，提供了这种解释。然而，如果我们要了解3He ADC测量并最佳地利用其诊断潜力，则必须回答大量问题。 在这个提议中，我们将扩展我们的数学模型，该模型将肺中的各向异性ADC测量与肺微结构参数相关联。该数学模型是基于肺的一个现实的结构，在腺泡水平的腺泡气道覆盖肺泡袖。肺内气体扩散的理论是基于我们的肺腺泡气道各向异性扩散的关键概念。 我们将对具有健康肺部的处死小鼠进行复杂的多维MR实验，以测试我们的数学模型的基本特征，ADC的各向异性。 我们将进一步开发并测试我们的新扩散3 He MRI技术，用于在生理学与人类相似的肺气肿犬模型上进行断层扫描“肺活检”，并建立CT确定的肺气肿严重程度与3 He之间的定量关系各向异性扩散系数。 我们将使用3He弥散和通气MRI与CT一起研究正常人和肺气肿患者。这三种技术的相互比较将建立CT、肺通气和各向异性ADC测量之间的定量关系，并将为每种方式获得的结果的新解释开辟可能性。 潜在的影响是巨大的。将建立肺气肿进展的综合临床图像，从肺泡变形的初始发作到以肺功能急剧丧失为特征的最终阶段。新的方法将是足够敏感的，以允许早期诊断肺气肿，这将改善病人的治疗。网站（==

EXCEEDTHESPACE PROVIDED. Emphysema is a major medical problem in the US and worldwide. Diagnostic methods for the evaluation of emphysema should be sensitive to regional lung structure at the alveolar level. Diffusion MRI with hyperpolarized 3He gas that evaluates the 3He-gas ADC (apparent diffusion coefficient) can provide this sensitivity. It offers information on lung microstructure and function not provided by traditional imaging modalities and pulmonary function tests. With 3He diffusion MRI, alveolar size and the integrity of alveolar walls can be evaluated, even though the alveoli are too small to be resolved by direct imaging. This points to the large potential for clinical application of ADC measurements with hyperpolarized 3He gas. However, until recently it was not clear what specific features of lung structure are probed by 3He gas ADC measurements. Recently we proposed a theoretical model based on a large body of histology data that provides this explanation. However, substantial questions must be answered if we are to understand the 3He ADC measurement and optimally exploit its diagnostic potential. In this proposal we will extend our mathematical model that relates anisotropic ADC measurements in lung to lung microstructural parameters. The mathematical model is based on a realistic structure of lung at the acinar level described in terms of acinar airways covered with alveolar sleeves. The theory of gas diffusion in lung is based on our key concept of anisotropic diffusion in lung acinar airways. We will conduct sophisticated multi-dimensional MR experiments on sacrificed mice with healthy lungs to test the fundamental feature of our mathematical model, the anisotropy of ADC. We will develop further and test our new diffusion 3He MRI technique for tomographic "lung biopsy" on a canine model of emphysema with physiology similar to human and establish a quantitative relationship between the severity of emphysema as determined by CT and the 3He anisotropic diffusivities. We will use 3He diffusion and ventilation MRI together with CT to study normal human subjects and patients with emphysema. Inter-comparison of these three techniques will establish quantitative relationships between CT, lung ventilation and anisotropic ADC measurements and will open up possibilities for new interpretations of results obtained by each modality. The potential implications are significant. A comprehensive clinical picture of emphysema progression, from initial onset of the alveolar deformation to the final stage, characterized by dramatic loss of lung function, will be established. New methods will be sensitive enough to allow early diagnosis of emphysema that will improve patient treatment. PERFORMANCESITE( ========================================Section End===========================================