4种评估肺气肿的CT指标的比较及层厚和重建方式的影响

发布时间：2018-10-21 17:44

【摘要】：目的探讨在慢性阻塞性肺疾病(COPD)患者中,评估肺气肿各CT指标与肺功能的相关性,分析层厚和重建方式对其的影响。方法入选COPD稳定期患者39例,完成肺功能各项检测和吸气相胸部CT扫描。CT图像以层厚0.625、1.25、5、7.5和10 mm进行标准重建,以层厚0.625 mm和1.25mm进行高频重建。用最佳阈值及默认阈值测量低衰减区比例(LAA%)、全肺像素CT值直方图上第15百分位点对应的CT值(Perc 15)、平均肺密度和全肺体积。分析不同层厚和重建方式对这些指标的影响,以及这些指标与肺功能的相关性。结果LAA%随层厚增大而减小,高频重建高于标准重建。Perc 15、平均肺密度随层厚增加升高,高频重建低于标准重建。而全肺体积的测量所受影响较小。在各层厚及重建方式下,第1秒用力呼气容积(FEV1)、FEV1占预计值的百分比(FEV1%pred)、FEV1占用力肺活量(FVC)的比例(FEV1/FVC)、最大呼气中段流量占预计值的百分比(MMEF%pred)、一氧化碳弥散量(DLCO)、DLCO占预计值的百分比(DLCO%pred)、单位弥散量占预计值的百分比(DLCO/VA%pred)与LAA%呈负相关(P0.05),与Perc 15呈正相关(P0.05)。FEV1%pred、FEV1/FVC与平均肺密度呈正相关(P0.05)。肺总量(TLC)、残气量(RV)、残总比(RV/TLC)与CT所示全肺体积呈正相关(P0.05)。对于肺通气指标和弥散指标,LAA%和Perc 15与其的相关性高于平均肺密度和全肺体积。对于肺容积指标,CT所示全肺体积高于其他参数。层厚对肺气肿CT评估结果和肺功能的相关性影响不大;而LAA%、Perc 15与部分肺通气指标(如FEV1)的相关性,高频重建高于标准重建。结论在胸部CT中测算LAA%、Perc15能较好反映肺功能中的通气和弥散指标,CT所示全肺体积能较好反映肺功能中的容积指标。进行CT肺气肿评估时,应注意层厚、重建方式的同一性,若有不同,需进行相应修正。
[Abstract]:Objective to investigate the correlation between CT and pulmonary function in patients with chronic obstructive pulmonary disease (COPD). Methods 39 patients with stable COPD were enrolled in this study. Lung function was measured and chest CT scanning was performed on inspiratory phase. CT images were reconstructed with standard slice thickness of 0.625 ~ 1.25U 57.5 and 10 mm, and high frequency reconstruction with slice thickness of 0.625 mm and 1.25mm. The low attenuation area ratio (LAA%), the CT value (Perc 15) corresponding to the 15th percentile on the histogram, the mean lung density and the whole lung volume were measured by the best threshold and default threshold. The influence of different thickness and reconstruction mode on these indexes and the correlation between these indexes and lung function were analyzed. Results LAA% decreased with the increase of lamellar thickness, high frequency reconstruction was higher than standard reconstruction, Perc 15, the mean pulmonary density increased with the increase of lamellar thickness, and high frequency reconstruction was lower than the standard reconstruction. The measurement of whole lung volume was less affected. Under the thickness of each layer and the method of reconstruction, Forced expiratory volume (FEV1), percentage of FEV1 to predicted value (FEV1%pred), ratio of FEV1 occupancy to vital capacity (FVC) (FEV1/FVC), maximum mid-expiratory flow (MMEF%pred), percentage of carbon monoxide dispersion (DLCO), DLCO) to predicted value (DLCO%pred), unit diffusion volume (DLCO%pred) The percentage of predicted value (DLCO/VA%pred) was negatively correlated with LAA% (P0.05) and positively correlated with Perc 15 (P0.05). FEV1%pred,FEV1/FVC was positively correlated with mean pulmonary density (P0.05). There was a positive correlation between the total (TLC), residual volume of lung (RV/TLC) and the whole lung volume as shown by CT (P0.05). The correlation between LAA% and Perc 15 was higher than that of mean lung density and whole lung volume for pulmonary ventilation index and diffusion index. For lung volume index, CT showed that the whole lung volume was higher than other parameters. Lamellar thickness had little effect on the correlation between CT evaluation results and pulmonary function, while LAA%,Perc 15 had a higher correlation with some pulmonary ventilation indexes (such as FEV1), and high frequency reconstruction was higher than that of standard reconstruction. Conclusion the measurement of LAA%,Perc15 in chest CT can better reflect the ventilation and diffusion index in lung function, and the whole lung volume in CT can better reflect the volume index of lung function. In evaluating CT emphysema, we should pay attention to the thickness of layers and the identity of reconstruction methods.
【作者单位】：上海交通大学医学院附属瑞金医院北院呼吸内科;上海交通大学医学院附属瑞金医院放射科;
【基金】：上海申康医院发展中心慢性病综合防治项目(SHDC12012305) 上海交通大学医学院附属瑞金医院北院研究基金(2015ZY04)~~
【分类号】：R563.3;R816.4

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