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目的 用呼吸门控定量CT分析慢性阻塞性肺气肿、慢性支气管炎的平均肺密度 (MLD)和像素指数 (PI)的分布。方法 40例正常人、2 3例肺气肿病人及 15例慢性支气管炎患者 ,在 5 0 %肺活量 (VC)时用螺旋CT扫描全肺 ,在 10 %VC和 90 %VC时于隆突层及隆突上、下各 5cm处行高分辨率CT(HRCT)扫描 ,分析不同病种不同呼吸时相的MLD和 <- 910HU的肺区所占的比例 ,即PI的变化 ,并与肺功能 (PFTs)和形态学结果比较。结果 10 %VC时 ,肺气肿组与慢性支气管炎组的MLD降低 ,平均值分别为 - 831 8HU和 - 796 8HU ,与正常组为 - 745 3HU比较 ,统计学上差异有非常显著性意义 (P <0 0 1) ;90 %VC时 ,仅肺气肿组MLD下降 ,统计学上差异有显著性意义 (P <0 0 5 ) ;PI变化有同样规律 ,只是PI表现为增加。定量CT提示的病变与形态学一致 ,定量CT较肺功能敏感 ,呼气末定量CT还可以弥补CT形态学发现率低的不足。结论 CT与定量CT结合实现了形态与功能的统一 ,可以提供更多的诊断信息 ,完善疾病的诊断。
OBJECTIVE: To determine the distribution of mean lung density (MLD) and pixel index (PI) of chronic obstructive pulmonary emphysema and chronic bronchitis by quantitatively using respiratory gated CT. Methods Forty normal subjects, 23 patients with emphysema and 15 patients with chronic bronchitis were scanned by spiral CT at 50% vital capacity (VC) And 5cm above and below the carina underwent high resolution CT (HRCT) scanning. The proportion of MLD in different respiratory phases and the proportion of <- 910HU lung area, ie, changes in PI, were analyzed and compared with pulmonary function (PFTs) and morphological results. Results MLD in emphysematous group and chronic bronchitis group were lower at 10% VC, the average values were -831 8HU and -796 8HU, respectively, which were significantly different from those in normal group (-745 3HU) P <0.01). MLD in emphysema group decreased only at 90% VC, the difference was statistically significant (P <0 05). The same pattern was observed in PI, but PI was increased. Quantitative CT tips and morphological lesions consistent quantitative lung function-sensitive CT, quantitative end-expiratory CT can make up for the lack of detection of CT morphology. Conclusion CT combined with quantitative CT to achieve the unity of morphology and function, can provide more diagnostic information, improve the diagnosis of the disease.