Quantitative computed tomography and predictive modelling for COPD exacerbations

In COPD, acute exacerbations (AECOPD) are major contributors to morbidity and mortality, emphasising the need for effective stratification of individuals at high risk. Quantitative computed tomography (qCT) refers to the extraction of numerical data from CT images to objectively characterise anatomical and functional features, and it has been increasingly investigated in COPD assessment. We systematically reviewed the literature to evaluate the use of qCT for the diagnosis and prognosis of AECOPD. Of 362 screened records, 18 studies were included in this review. No studies were identified that used qCT features to diagnose AECOPD in CT scans made at the point of exacerbation. 11 studies reported qCT features identified in CT scans performed in stable COPD that are associated with frequent AECOPD and seven studies developed and tested models integrating CT features for the prediction of AECOPD. Across these studies, greater emphysema extent, thicker bronchial walls and increased air trapping were associated with higher exacerbation risk. However, current evidence is limited by heterogeneity in study design and lack of prospective validation. This review highlights the potential of quantitative CT analysis, which may be further enhanced by the integration of automated software, to support the development of imaging biomarkers for AECOPD. Future research is needed to refine qCT features for diagnosing AECOPD and establish CT-based tools that can predict AECOPD.