Zagers H, Vrooman H A, Aarts N J, Stolk J, Schultze Kool L J, Dijkman J H, Van Voorthuisen A E, Reiber J H
Department of Diagnostic Radiology and Nuclear Medicine, Leiden University Hospital, The Netherlands.
Invest Radiol. 1996 Dec;31(12):761-7. doi: 10.1097/00004424-199612000-00005.
The authors assessed the progression of pulmonary emphysema by means of quantitative analysis of computed tomography images.
Twenty-three patients suffering from emphysema due to an alpha 1-antitrypsin deficiency, aged 45 +/- 7 years and exsmokers, were scanned twice with a 1-year time interval. At 90% of the vital lung capacity, slices with a thickness of 1.5 mm were acquired at the level of the carina and 5 cm above the carina; slices with a thickness of 1 cm were acquired 5 cm below the carina. The entire lung was scanned spirally at a respiratory status, corresponding with 75% of the total lung capacity at baseline. The mean lung densities (MLD) were calculated in an objective manner with new analytic software featuring automated detection of the lung contours.
Mean lung densities decreased by 14.2 +/- 12.0 Hounsfield units (HU; P < 0.001) above the carina, by 18.1 +/- 14.4 HU (P < 0.001) at the carina level, by 23.6 +/- 15.0 HU (P < 0.001) below the carina, and by 12.8 +/- 22.2 HU (P < 0.01) for the entire lung. The decrease in MLD was most obvious in the lower lung lobes. For the same patient group, the annual decrease in the forced expiratory volume (FEV1) and the carbon monoxide-diffusion were 120 +/- 190 mL (P < 0.01) and 10 +/- 70 mmol/kg/minute ( P < 0.2), respectively. No significant correlation was found between the decrease in MLD and the decrease in FEV1.
Progression of emphysema can be assessed in an objective manner based on the mean lung density (MLD), measured from computed tomography volume scans as well as from single-slice scans. Mean lung density has proved to be more sensitive than FEV1 and carbon monoxide-diffusion.
作者通过对计算机断层扫描图像进行定量分析来评估肺气肿的进展情况。
23例因α1-抗胰蛋白酶缺乏而患肺气肿的患者，年龄45±7岁，已戒烟，在1年的时间间隔内进行了两次扫描。在肺活量的90%时，于隆突水平及隆突上方5 cm处获取厚度为1.5 mm的切片；在隆突下方5 cm处获取厚度为1 cm的切片。在与基线时肺总量的75%相对应的呼吸状态下对整个肺部进行螺旋扫描。使用具有自动检测肺轮廓功能的新型分析软件以客观方式计算平均肺密度（MLD）。
隆突上方平均肺密度下降14.2±12.0亨氏单位（HU；P<0.001），隆突水平下降18.1±14.4 HU（P<0.001），隆突下方下降23.6±15.0 HU（P<0.001），整个肺部下降12.8±22.2 HU（P<0.01）。MLD的下降在肺下叶最为明显。对于同一患者组，用力呼气量（FEV1）和一氧化碳弥散量的年下降分别为120±190 mL（P<0.01）和10±70 mmol/kg/分钟（P<0.2）。未发现MLD的下降与FEV1的下降之间存在显著相关性。
基于从计算机断层扫描容积扫描以及单层扫描测量得到的平均肺密度（MLD），可以客观地评估肺气肿的进展情况。平均肺密度已被证明比FEV1和一氧化碳弥散更为敏感。
