Quantitative CT evaluation of extrapulmonary lesions in chronic obstructive pulmonary disease: a narrative review

Chronic obstructive pulmonary disease (COPD) is a significant global health challenge characterized by persistent respiratory symptoms and airflow limitation. Recent advancements in computed tomography (CT) have enhanced our understanding of COPD, particularly in diagnosing extrapulmonary comorbidities. This review aims to summarize the current findings on extrapulmonary manifestations in COPD patients and the role of quantitative computed tomography (QCT) in evaluating these comorbidities.

A comprehensive literature search was conducted using PubMed and Web of Science databases, covering studies from January 1999 to May 2024. Keywords included "COPD", "chronic obstructive pulmonary disease", "muscle", "adipose tissue", "coronary artery calcification", "bone density", "extrapulmonary manifestations", and "Quantitative Computed Tomography". Inclusion criteria focused on studies involving COPD patients using QCT to identify extrapulmonary manifestations, published in peer-reviewed journals and available in English.

The review highlights significant findings, such as the reduction in muscle mass and bone density and the increase in coronary artery calcification (CAC) in COPD patients, all closely associated with disease severity and prognosis. Key metrics evaluated include mid-thigh muscle cross-sectional area, pectoralis muscle area, erector spinae muscles, and bone density. Advanced CT analysis techniques, including artificial intelligence (AI) and machine learning, are emphasized as crucial for improving assessment accuracy and efficiency. Subcutaneous fat reduction and CAC are identified as critical indicators of mortality and disease progression.

Quantitative CT evaluation is vital for understanding and managing extrapulmonary lesions in COPD. Future research should focus on establishing suitable measurement tools and methods and defining critical thresholds for treatment efficacy. The integration of advanced CT techniques and interdisciplinary approaches is essential for enhancing diagnostic accuracy and developing personalized treatment strategies for COPD patients.