Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Coreline Soft, Co., Ltd, Seoul, Korea.
Korean J Radiol. 2021 Oct;22(10):1719-1729. doi: 10.3348/kjr.2021.0033. Epub 2021 Jul 1.
Emphysema and small-airway disease are the two major components of chronic obstructive pulmonary disease (COPD). We propose a novel method of quantitative computed tomography (CT) emphysema air-trapping composite (EAtC) mapping to assess each COPD component. We analyzed the potential use of this method for assessing lung function in patients with COPD.
A total of 584 patients with COPD underwent inspiration and expiration CTs. Using pairwise analysis of inspiration and expiration CTs with non-rigid registration, EAtC mapping classified lung parenchyma into three areas: Normal, functional air trapping (fAT), and emphysema (Emph). We defined fAT as the area with a density change of less than 60 Hounsfield units (HU) between inspiration and expiration CTs among areas with a density less than -856 HU on inspiration CT. The volume fraction of each area was compared with clinical parameters and pulmonary function tests (PFTs). The results were compared with those of parametric response mapping (PRM) analysis.
The relative volumes of the EAtC classes differed according to the Global Initiative for Chronic Obstructive Lung Disease stages ( < 0.001). Each class showed moderate correlations with forced expiratory volume in 1 second (FEV) and FEV/forced vital capacity (FVC) ( = -0.659-0.674, < 0.001). Both fAT and Emph were significant predictors of FEV and FEV/FVC (R² = 0.352 and 0.488, respectively; < 0.001). fAT was a significant predictor of mean forced expiratory flow between 25% and 75% and residual volume/total vital capacity (R² = 0.264 and 0.233, respectively; < 0.001), while Emph and age were significant predictors of carbon monoxide diffusing capacity (R² = 0.303; < 0.001). fAT showed better correlations with PFTs than with small-airway disease on PRM.
The proposed quantitative CT EAtC mapping provides comprehensive lung functional information on each disease component of COPD, which may serve as an imaging biomarker of lung function.
肺气肿和小气道疾病是慢性阻塞性肺疾病（COPD）的两个主要组成部分。我们提出了一种新的定量计算机断层扫描（CT）肺气肿空气滞留复合（EAtC）映射方法来评估每个 COPD 成分。我们分析了该方法在评估 COPD 患者肺功能方面的潜在用途。
共 584 例 COPD 患者接受了吸气和呼气 CT 检查。使用吸气和呼气 CT 的非刚性配准进行成对分析，EAtC 映射将肺实质分为三个区域：正常、功能性空气滞留（fAT）和肺气肿（Emph）。我们将 fAT 定义为吸气 CT 密度小于-856 HU 且密度变化小于 60 HU 的区域。比较了每个区域的体积分数与临床参数和肺功能测试（PFT）的关系。结果与参数反应映射（PRM）分析进行了比较。
EAtC 类别的相对体积因全球慢性阻塞性肺疾病倡议（GOLD）分期不同而有所不同（<0.001）。每个类别与 1 秒用力呼气量（FEV）和 FEV/FVC 均呈中度相关（=-0.659 至-0.674，<0.001）。fAT 和 Emph 都是 FEV 和 FEV/FVC 的重要预测因子（R²分别为 0.352 和 0.488，均<0.001）。fAT 是 25%至 75%用力呼气流量和残气量/总肺活量的重要预测因子（R²分别为 0.264 和 0.233，均<0.001），而 Emph 和年龄是一氧化碳弥散量的重要预测因子（R²为 0.303；<0.001）。fAT 与 PFT 的相关性优于 PRM 中的小气道疾病。
所提出的定量 CT EAtC 映射为 COPD 的每个疾病成分提供了全面的肺功能信息，可作为肺功能的影像学生物标志物。
