Berger Patrick, Perot Vincent, Desbarats Pascal, Tunon-de-Lara José Manuel, Marthan Roger, Laurent François
Laboratoire de Physiologie Cellulaire Respiratoire, Institut National de la Santé et de la Recherche Médicale, E-0356, Université Victor Ségalen, Bordeaux, France.
Radiology. 2005 Jun;235(3):1055-64. doi: 10.1148/radiol.2353040121. Epub 2005 Apr 15.
To design and validate a dedicated software tool to measure airway dimensions on thin-section computed tomographic (CT) images and to use the tool to prospectively compare airway wall thickness in nonsmokers with normal lung function with that in smokers with and without chronic obstructive pulmonary disease (COPD).
All subjects gave written informed consent. The study was approved by local ethics committee. With Laplacian of Gaussian algorithm, software was tested in phantom and excised sheep lung fixed in inflation and validated with Bland-Altman analysis. Study prospectively included nine nonsmokers (six women, three men; mean age, 53 years +/- 5.6 [standard error of the mean]) with normal lung function (group 1), seven smokers (three women, four men; mean age, 56 years +/- 5.6) with normal lung function (group 2), and eight smokers (zero women, eight men; mean age, 65 years +/- 4.0) with COPD. Calculations were determined with spirometrically gated CT: For each selected bronchus, the wall area (WA), internal area (IA), airway caliber (sum of IA and WA), and WA/IA ratio were calculated. For each patient, summation of WA to summation of IA (SigmaWA/SigmaIA) ratio, which reflected normalized airway wall thickness, was calculated. Groups were compared by using analysis of variance with generalized linear model and unpaired t test. Pearson correlation coefficient was used to assess correlation between software measurements and pulmonary function test results.
Comparison of measurements in phantom and excised sheep lung with algorithm measurements revealed that the latter were reliable and repeatable. In clinical study, SigmaWA/SigmaIA ratio was significantly different among three groups (P < .001). Normalized airway wall thickness and IA were significantly related to lung function test data, including forced expiratory volume in 1 second (r = -0.54, P = .006), specific airway conductance (r = -0.45, P = .03), and forced expiratory flow between 25% and 75% of vital capacity (r = -0.65, P < .001).
This software provides accurate and reproducible measurements of IA and WA of bronchi on thin-section CT images and demonstrates that in vivo normalized airway wall thickness was larger in smokers with COPD than it was in smokers or nonsmokers without COPD.
设计并验证一款专用软件工具，用于在薄层计算机断层扫描（CT）图像上测量气道尺寸，并使用该工具前瞻性地比较肺功能正常的非吸烟者与患有和未患有慢性阻塞性肺疾病（COPD）的吸烟者的气道壁厚度。
所有受试者均签署了书面知情同意书。该研究获得了当地伦理委员会的批准。使用高斯-拉普拉斯算法，在模型以及充气固定的离体羊肺中对软件进行测试，并通过布兰德-奥特曼分析进行验证。前瞻性研究纳入了9名肺功能正常的非吸烟者（6名女性，3名男性；平均年龄53岁±5.6[平均标准误差]）（第1组）、7名肺功能正常的吸烟者（3名女性，4名男性；平均年龄56岁±5.6）（第2组）以及8名患有COPD的吸烟者（0名女性，8名男性；平均年龄65岁±4.0）。通过肺活量计门控CT进行计算：对于每个选定的支气管，计算壁面积（WA）、内部面积（IA）、气道管径（IA与WA之和）以及WA/IA比值。对于每位患者，计算WA总和与IA总和的比值（SigmaWA/SigmaIA），该比值反映了标准化气道壁厚度。使用广义线性模型的方差分析和不成对t检验对各组进行比较。采用Pearson相关系数评估软件测量值与肺功能测试结果之间的相关性。
模型和离体羊肺测量值与算法测量值的比较表明，算法测量值可靠且可重复。在临床研究中，三组之间的SigmaWA/SigmaIA比值存在显著差异（P <.001）。标准化气道壁厚度和IA与肺功能测试数据显著相关，包括第1秒用力呼气量（r = -0.54，P =.006）、比气道传导率（r = -0.45，P =.03）以及肺活量25%至75%之间的用力呼气流量（r = -0.65，P <.001）。
该软件可在薄层CT图像上准确且可重复地测量支气管的IA和WA，并表明患有COPD的吸烟者体内标准化气道壁厚度大于未患有COPD的吸烟者或非吸烟者。
