中文摘要：

目的 利用64层CT灌注成像（CTPI）研究兔放射性肺损伤（RILI）发病进程中血流动力学变化规律,并探讨其病理基础.方法 健康新西兰大白兔72只,利用随机数字表分为2组：实验组（36只）25 Gy单侧全肺单次照射,对照组（36只）单侧全肺假照射,2组按照射后1、6、12、24、48、72 h,和1、2、4、8、16、24周各分为12个亚组.每只兔于照射前和照射后所处亚组时间点做HRCT和CTPI,后取肺组织行光镜、电镜观察,将同期CTPI表现、病理变化及HRCT征象作对照分析.实验组与对照组CTPI参数比较采用t检验,CTPI参数与病理观察值的相关性采用两变量直线相关分析,CTPI与HRCT对RILI检出率比较采用x2检验.结果 （1）对照组肺CTPI参数在各时间点上保持在相对稳定的水平.实验组肺实质相对血流量（rBF）、相对血容量（rBV）和毛细血管相对通透性（rPS）在照射前和照射后72 h、2周分别为1.01±0.09、1.86±0.20、1.43±0.12,1.03±0.08、1.63±0.19、1.56±0.14,0.96±0.12、1.54±0.17、1.83±0.24,各时间点差异均有统计学意义（t=2.90～6.37,P值均＜0.05）.（2）实验组受照射肺病理变化以毛细血管内皮细胞、基底膜和肺泡上皮细胞损伤为主,并随时间呈现一定规律性.实验组照射后肺rBF、rBV与病理改变有显著相关性（r值分别为0.74、0.83,P值均＜0.05）,rPS与毛细血管外红细胞数、毛细血管基底膜破坏之间有显著依存关系（r值分别为0.87、0.88,P值均＜0.01）.（3）CTPI对RILI的检出率（72.2％,26/36）高于HRCT（16.7％,6/36）,两者差异有统计学意义（x2=4.37,P=0.036）.结论 CTPI参数初步揭示了RILI过程中的血流动力学演变规律,并间接反映以血管内皮细胞损伤为主要变化的病理生理状态；RILI的CTPI异常在时间上先于HRCT,有望用于RILI早期预报.

英文摘要：

Objective To study the hemodynamic changes and pathologic foundation of rabbit models of radiation-induced lung injury （RILI） via 64-slice CT pulmonary perfusion imaging （ CTPI）,in order to seek the correlation between the alterations of the hemodynamic parameters and pathophysiology.Methods Seventy-two healthy New Zealand rabbits were randomly classified into two groups：test group （ n =36）,received 25 Gy with single fraction irradiation in a whole unilateral lung; control group （ n =36）,received sham-irradiation.Each group was divided into 12 subgroups respectively according to post- and pseudo-irradiation time points （1,6,12,24,48,72 h and 1,2,4,8,16,24 w）.Each rabbit underwent HRCT and CTPI at every pre- and post-radiation time point.All rabbits were sacrificed,and morphology of specimens was observed using light- and electron microscope. The changing regularity of HRCT,CTPI parameters and pathology were analyzed and compared with each other in order to find the correlation among them.The CTPI parameters of the test and control groups were compared using t test.The CTPI parameters and pathological values were analyzed using linear correlation with two variables,the detection rates of RILI by CTPI and HRCT was compared using Chi-square test.Results （ 1 ） The changes of CTPI parameters from control group after irradiation was relatively stable,but in test group those parameters including rBF,rBV and rPS,at pre- and post-irradiation time points （0,72 h and 2 w）,were respectively 1.01 ± 0.09,1.86 ± 0.20,1.43 ±0.12,1.03 ±0.08,1.63 ±0.19,1.56±0.14,0.96±0.12,1.54 ±0.17 and 1.83 ±0.24.The corresponding parameters before and after irradiation were significantly different （ t =2.90-6.37,P 〉 0.05）.（2）In test group,capillary endothelial cells,basement membrane and alveolar epithelial cells,as the main injury targets,showed certain alterations in pathology.There was a significant correlation between the changes of CTPI parameters （ rBF and rBV） and pathophysiology in con