我国是全球PM2.5污染程度最高的地区之一，PM2.5暴露导致人肺功能减低，严重者致COPD甚至肿瘤等重大疾病，是引起死亡重要因素。早期发现PM2.5致肺部微结构及局部功能变化，对于及早干预和治疗，改善预后有十分重要的意义。申请者前期运用MR首过法检出长期烟雾暴露健康人的局部肺灌注异常；成功建成香烟烟雾PM2.5暴露大鼠模型。microCT和同步辐射成像可直接显示肺组织的细支气管和肺泡结构，且SRI能定量腺泡容积、数量。环境空气PM2.5暴露后肺部微结构及局部功能变化的详情和规律，目前还不很清楚。本研究拟建立环境空气PM2.5慢性暴露的大鼠模型，利用MR灌注、microCT、同步辐射的多模态影像学手段综合评价大鼠血管、小气道、肺组织的演变规律，阐明PM2.5引起的肺部细微结构及局部功能的变化，明确早期影像特征，及其与病理组织学的对应关系,为PM2.5相关肺疾病的早期诊断和防治提供理论依据。

China is one of the world's regions with the highest degree of PM2.5 pollution, long-term exposure to PM2.5 will result in impairmentof lung function of healthy adults, even major diseases like COPD or lung cancer.PM2.5 is a great risk factor to death. The early detection of lung microstructure and local lung function caused by PM2.5 is very important to early intervention and improve the prognosis. MR perfusion imaging using first-pass could be implemented in early stage by applicants to detect the regional pulmonary perfusion abnormal of healthy smokers, and create a rat model of chronic exposure to PM2.5 in cigarette smoking. MicroCT and Synchrotron radiation imaging(SRI) can directly display the structure of the bronchioles and alveoli of the lung tissue；SRI could also quantify ration acinus volume, acinus surface area, alveolar quantity. So far it’s not quite clear to know the details and regularities of the variation of the microstructure and local features after exposure of PM 2.5 in ambient air. The study attempts to establish a rat model of chronic exposure to PM2.5 in ambient air, and evaluate the characteristics and early progress of vascular, airway and lung tissues using MR perfusion imaging, microCT and synchrotron radiation source, where it will help to define the early imaging features and the corresponding relationship between pathological histology, so as to provide a theoretical basis for early clinical intervention and treatment of PM2.5 associated lung diseases.