肺泡蛋白沉着症定量CT分析与肺功能相关性研究

目的 探讨定量CT参数与肺功能检杳指标在肺泡蛋白沉着症(PAP)全肺灌洗术前后的相关性及应用价值.方法 对20例PAP患者共37次肺CT及同期肺功能检查结果进行相关性分析.对15例20次(两肺19次,单肺1次)行全肺灌洗前后的CT资料进行对比分析.定量CT参数采用患者的最大吸气末全肺容积、全肺质量、全肺含气体积、平均肺体积、平均肺密度及全肺含气体积/全肺容积.肺功能检查指标采用用力肺活量(FVC)、第1秒用力呼吸量(FEV_1)、1秒率(FEV_1/FVC)、呼吸峰流速(PEF)、肺一氧化碳弥散量(D_LCO)以及肺一氧化碳弥散常数(D_LCO/VA),以中国成人肺功能正常参考值作为正常预计值,分别取其占正常预计值的百分比进行相关性分析.结果 (1)全肺质量与FVC%、FEV_1%具有相关性(均P<0.05);全肺含气体积与FVC%、(FEV_1/FVC)%、D_LCO%、D_LCO/VA%之间存在相关性(均P<0.05);平均肺体积、平均肺密度及全肺含气体积/全肺容积分别与FVC%、FEV_1%、(FEV_1/FVC)%、PEF%、D_LCO%、(DLCO/VA)%之间具有相关性(均P<0.05);在所有指标中以全肺含气体积/全肺容积与D_LCO%、(D_LCO/VA)%关系最密切(r=0.725、0.725,均P=0.000).(2)PAP患者经全肺灌洗术后,定最CT检查全肺质量显著减低(1613±459)g比(1293±351)g,P=0.000],两肺的平均肺密度明显减低(0.5178±0.15)g/ml比(0.4312±0.10)g/ml,P=0.000],平均肺体积明显增加(1.216±0.70)ml/g比(1.573±0.61)ml/g,P=0.001],全肺含气体积/全肺容积升高(0.5110±0.14比0.6005±0.10,P=0.000).全肺灌洗前后的全肺容积与全肺含气体积呈正相关(r=0.911,P=0.000).结论 通过最大吸气末行螺旋CT扫描获得的PAP的定量CT参数与肺功能各项指标之间相关性好,因而本法是一种有效的CT肺功能成像技术.全肺灌洗术后以定量CT结果中的全肺质量、平均肺密度及平均含气肺体积改善明显.

Correlation between quantitative CT findings and pulmonary function tests in pulmonary alveolar proteinosis

Objective To evaluate the use and correlation of quantitative CT findings and pulmonary function tests (PFTs) before and after whole lung lavage (WLL) in pulmonary alveolar proteinosis (PAP). Methods Correlation between findings of 37 pulmonary CT scans and contemporary PFTs was analyzed in 20 patients with PAP. A comparison was performed in 15 PAP patients between their quantitative CT findings before and after a total of 20 sessions of WLL (19 of both-lung lavage and 1 of single-lung lavage). Parameters of quantitative CT analysis included maximal end-tidal total lung volume, total lung weight, airspace volume, mean lung volume, mean lung density and the ratio of airspace volume over total lung volume. PFTs were used to measure forced vital capacity (FVC), forced expiratory volume in one second (FEV_1), FEV_1/FVC, peak expiratory flow(PEF), diffusion capacity for carbon monoxide of the lung(D_LCO) and carbon monoxide diffusing capacity per liter of alveolar(D_LCO/VA). The Chinese adult normal reference values of pulmonary function were regarded as the normal predictive values, and the ratios of measured values/normal predictive values were used for correlation analysis. Results (1) Total lung weight showed correlation with FVC% and FEV_1% (both P<0.05). Airspace volume showed correlation with FVC% , (FEV_1/FVC) %, D_LCO%, (D_LCO/VA) % (All/P<0.05). Mean lung volume, mean lung density and airspace volume/total lung volume were correlated well with FVC%, FEV_1%, (FEV_1/FVC)%, PEF%, D_LCO%, (D_LCO/VA)% (all P<0.05). The highest correlation was found between airspace volume/total lung volume and D_LCO% , (D_LCO/VA)% (r=0.725, 0.725, P=0.000, 0.000, respectively). (2) Following WLL, significant changes were found in total lung weight (1613±459)g vs (1293±351)g, P=0.000], mean lung density (0.5178±0.15) g/ml vs (0.4312±0.10) g/ml, P=0.000], mean lung volume (1.216±0.70) ml/g vs (1.573±0.61) ml/g, P=0.001] and airspace volume/total lung volume (0.5110±0.14 vs 0.6005±0.10, P= 0.000). The total lung volume was positively correlated with the airspace volume before and after WLL (r= 0.911, P=0.000). Conclusions Spiral CT scanning with maximal end-tidal volume can provide pulmonary quantitative analysis which shows good correlation with PFTs, and therefore may be an effective method for quantitative pulmonary function study. Significant changes in total lung weight, mean lung density and airspace volume/total lung volume are observed by quantitative CT after WLL.