Spirometric assessment of emphysema presence and severity as measured by quantitative CT and CT-based radiomics in COPD

Abstract

Background The mechanisms underlying airflow obstruction in COPD cannot be distinguished by standard spirometry. We ascertain whether mathematical modeling of airway biomechanical properties, as assessed from spirometry, could provide estimates of emphysema presence and severity, as quantified by computed tomography (CT) metrics and CT-based radiomics. Methods We quantified presence and severity of emphysema by standard CT metrics (VIDA) and co-registration analysis (ImbioLDA) of inspiratory-expiratory CT in 194 COPD patients who underwent pulmonary function testing. According to percentages of low attenuation area below − 950 Hounsfield Units (%LAA -950insp ) patients were classified as having no emphysema (NE) with %LAA -950insp < 6, moderate emphysema (ME) with %LAA -950insp ≥ 6 and < 14, and severe emphysema (SE) with %LAA -950insp ≥ 14. We also obtained stratified clusters of emphysema CT features by an automated unsupervised radiomics approach (CALIPER). An emphysema severity index (ESI), derived from mathematical modeling of the maximum expiratory flow-volume curve descending limb, was compared with pulmonary function data and the three CT classifications of emphysema presence and severity as derived from CT metrics and radiomics. Results ESI mean values and pulmonary function data differed significantly in the subgroups with different emphysema degree classified by VIDA, ImbioLDA and CALIPER ( p < 0.001 by ANOVA). ESI differentiated NE from ME/SE CT-classified patients (sensitivity 0.80, specificity 0.85, AUC 0.86) and SE from ME CT-classified patients (sensitivity 0.82, specificity 0.87, AUC 0.88). Conclusions Presence and severity of emphysema in patients with COPD, as quantified by CT metrics and radiomics can be estimated by mathematical modeling of airway function as derived from standard spirometry. Electronic supplementary material The online version of this article (10.1186/s12931-019-1049-3) contains supplementary material, which is available to authorized users.

A Comparative Evaluation of Computed Tomography Images for the Classification of Spirometric Severity of the Chronic Obstructive Pulmonary Disease with Deep Learning

“…Although there was no direct relationship between severe COPD exacerbation and visual structure on CT images [ 9 ], another report showed that quantitative assessment using fractal exponent D detected the changes associated with exacerbations [ 36 ]. Moreover, the lung condition depending on the severity of the disease is characterized on CT images [ 8 ], and the image classification by deep learning can be used for the spirometirc severity classification. Additionally, in the two-class classification by threshold image, the recall and precision are over 0.8 in GOLD ≥ 1, and symmetry is observed in dataset C in the McNemar–Bowker test.…”

“…It is important for the early diagnosis of COPD to perform spirometry to measure forced expiratory volume in 1 s (FEV 1 )/forced vital capacity (FVC). In particular, there is an abundance of studies [ 8 , 9 , 10 , 11 , 12 , 13 , 14 ] using CT, which have reported important findings on the loss of lung function, progression, and prognosis over time. However, in patients with clinical findings or contact history suspected of recent COVID-19 infection, pulmonary function tests may be discontinued or postponed, and there is concern that performing procedures such as deep breathing or forced expiration with maximal effort may cause the spread of contaminated droplets and aerosols to the surrounding area, resulting in the spread of infection.…”

Automated computed tomography quantification of fibrosis predicts prognosis in combined pulmonary fibrosis and emphysema in a real-world setting: a single-centre, retrospective study

“…Fibrosis extent was defined as the sum volume of honeycombing, ground glass, and reticular opacities [ 9 , 15 ]. The amount of normal lung was defined as the sum volume of normal lung and mild LAAs [ 16 ]. Emphysema was defined as the sum volume of moderate and severe LAAs.…”

Automated computed tomography quantification of fibrosis predicts prognosis in combined pulmonary fibrosis and emphysema in a real-world setting-A single-centre, retrospective study

“…Fibrosis extent was de ned as the sum volume of honeycombing, ground glass, and reticular opacities [9,15]. The amount of normal lung was de ned as the sum volume of normal lung and mild LAAs [16]. Emphysema was de ned as the sum volume of moderate and severe LAAs.…”