UBC Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, BC, Canada.
Respiration. 2017;94(4):336-345. doi: 10.1159/000478865. Epub 2017 Aug 23.
Disease accumulates in the small airways without being detected by conventional measurements.
To quantify small airway disease using a novel computed tomography (CT) inspiratory-to-expiratory approach called the disease probability measure (DPM) and to investigate the association with pulmonary function measurements.
Participants from the population-based CanCOLD study were evaluated using full-inspiration/full-expiration CT and pulmonary function measurements. Full-inspiration and full-expiration CT images were registered, and each voxel was classified as emphysema, gas trapping (GasTrap) related to functional small airway disease, or normal using two classification approaches: parametric response map (PRM) and DPM (VIDA Diagnostics, Inc., Coralville, IA, USA).
The participants included never-smokers (n = 135), at risk (n = 97), Global Initiative for Chronic Obstructive Lung Disease I (GOLD I) (n = 140), and GOLD II chronic obstructive pulmonary disease (n = 96). PRMGasTrap and DPMGasTrap measurements were significantly elevated in GOLD II compared to never-smokers (p < 0.01) and at risk (p < 0.01), and for GOLD I compared to at risk (p < 0.05). Gas trapping measurements were significantly elevated in GOLD II compared to GOLD I (p < 0.0001) using the DPM classification only. Overall, DPM classified significantly more voxels as gas trapping than PRM (p < 0.0001); a spatial comparison revealed that the expiratory CT Hounsfield units (HU) for voxels classified as DPMGasTrap but PRMNormal (PRMNormal- DPMGasTrap = -785 ± 72 HU) were significantly reduced compared to voxels classified normal by both approaches (PRMNormal-DPMNormal = -722 ± 89 HU; p < 0.0001). DPM and PRMGasTrap measurements showed similar, significantly associations with forced expiratory volume in 1 s (FEV1) (p < 0.01), FEV1/forced vital capacity (p < 0.0001), residual volume/total lung capacity (p < 0.0001), bronchodilator response (p < 0.0001), and dyspnea (p < 0.05).
CT inspiratory-to-expiratory gas trapping measurements are significantly associated with pulmonary function and symptoms. There are quantitative and spatial differences between PRM and DPM classification that need pathological investigation.
传统测量方法无法检测到小气道疾病的累积。
使用一种新的计算机断层扫描（CT）吸气到呼气方法（称为疾病概率测量（DPM））来量化小气道疾病，并研究其与肺功能测量的相关性。
从基于人群的 CanCOLD 研究中选取参与者，使用全吸气/全呼气 CT 和肺功能测量进行评估。对全吸气和全呼气 CT 图像进行配准，使用两种分类方法（参数响应图（PRM）和 DPM（VIDA Diagnostics，Inc.，Coralville，IA，USA））对每个体素进行分类，分类为肺气肿、与功能性小气道疾病相关的气体潴留（GasTrap）或正常。
参与者包括从不吸烟者（n = 135）、有风险者（n = 97）、慢性阻塞性肺疾病全球倡议 I 期（GOLD I）（n = 140）和 GOLD II 慢性阻塞性肺疾病（n = 96）。与从不吸烟者（p < 0.01）和有风险者（p < 0.01）相比，GOLD II 患者的 PRMGasTrap 和 DPMGasTrap 测量值显著升高，与有风险者相比，GOLD I 患者的测量值也显著升高（p < 0.05）。仅使用 DPM 分类，GOLD II 患者的气体潴留测量值显著高于 GOLD I（p < 0.0001）。总体而言，DPM 分类为气体潴留的体素明显多于 PRM（p < 0.0001）；空间比较显示，被 DPM 分类为 GasTrap 但被 PRM 分类为 Normal 的体素的 CT 呼气 HU（DPMNormal-PRMNormal = -785 ± 72 HU）明显低于两种方法均分类为 Normal 的体素（PRMNormal-DPMNormal = -722 ± 89 HU；p < 0.0001）。DPM 和 PRMGasTrap 测量值与 1 秒用力呼气量（FEV1）（p < 0.01）、FEV1/用力肺活量（p < 0.0001）、残气量/总肺容量（p < 0.0001）、支气管扩张剂反应（p < 0.0001）和呼吸困难（p < 0.05）均呈显著相关。
CT 吸气到呼气气体潴留测量与肺功能和症状显著相关。PRM 和 DPM 分类之间存在定量和空间差异，需要进行病理学研究。
