超极化气体磁共振成像在实验性肺气肿测量中的应用

Magnetic resonance imaging with hyperpolarized gases for experimental pulmonary emphysema

磁共振成像(MRI)及以超极化3氦和129氙作为气体造影剂的MRI是肺功能整体评价的新方法,以气体极化为充足MR信号来源的MRI是有高度空间分辩的非侵入与非破坏性小动物纵向成像技术,具有肺气腔能呼吸超极化气体氦和氙直接成像的优点。MRI已成为一种研究肺疾病小动物模型形态学和功能变化有用的临床前药物评价工具。文中简要介绍小动物肺气肿模型MRI技术及其在药物研究中的应用,包括在弹性蛋白酶所致家兔肺气肿模型,比较超极化3氦和129氙扩散MRI的显微形态学和3氦和129氙ADC的肺组织学敏感性和可重复性,并评价3氦和129氙扩散MRI测定经时肺气肿程度变化的能力,以及质子MRI评价弹性蛋白酶所致自主呼吸肺气肿大鼠的肺形态学和功能变化。

Magnetic resonance imaging （MRI） and MRI with hyperpolarized ^3He and ^129Xe as gaseous contrast agents are new methods for evaluating lung function in vivo. MRI with polarized gases as rich MR signal sources offers a noninvasive and nondestructive technology for imaging small animals longitudinally with high spatial resolution. A major advantage of hyperpolarized gas MR is direct imaging of the gas spaces of the lung using breathable gases such as helium and xenon. MRI has become a valuable tool for drug evaluation in pre-clinical studies to reveal morphologic and functional changes in small animal models of lung diseases. This paper briefly introduced the progress in studies of MR imaging techniques for small animal models of pulmonary emphysema. Especially, it compared hyperpolarized ^3 He and ^129Xe diffusion MRI with lung morphometry, and the sensitivities and repeatability of ^3He and ^129Xe apparent diffusion coefficient （ADCs） with lung histology. The paper also evaluated the ability of ^3He and ^129Xe diffusion MRI to detect the changes in the degree of emphysema over time in rabbit model of elastase-induced emphysema. Proton MRI can be used as a noninvasive tool to assess elastase-induced lung damage in spontaneously breathing rats. These methods are useful for study of the drug.