High-Resolution Computed Tomography in the Early Detection of Pulmonary Emphysema: Imaging Patterns, Quantitative Assessment, and Clinical Implications

Background: Pulmonary emphysema, a major structural component of chronic obstructive pulmonary disease (COPD), is characterized by irreversible destruction of alveolar walls and permanent enlargement of distal airspaces. Early emphysematous changes often remain clinically silent and may not be detected by conventional chest radiography or spirometry. With advances in imaging technology, high-resolution computed tomography (HRCT) has emerged as the most sensitive and specific imaging modality for detecting early and subclinical emphysema, allowing detailed visualization of lung parenchyma and subtle structural abnormalities. Objectives: This review aims to comprehensively analyze the imaging spectrum of early pulmonary emphysema on HRCT, describe qualitative and quantitative imaging patterns, and critically evaluate their clinical relevance, prognostic implications, and correlation with functional impairment. Materials and Methods: A systematic narrative review of published literature was conducted using electronic databases including PubMed/MEDLINE, Google Scholar, Scopus, Web of Science, and Embase. Original research articles, review articles, meta-analyses, and consensus statements published in English were included. Studies focusing on HRCT features of emphysema, early disease detection, quantitative CT analysis, and clinico-radiological correlations were reviewed. Relevant data were extracted, synthesized, and analyzed descriptively. Results: HRCT demonstrates superior sensitivity in detecting early emphysematous changes compared to conventional imaging and pulmonary function tests. Characteristic findings include focal and diffuse low-attenuation areas, centrilobular lucencies, subpleural emphysematous spaces, and loss of normal vascular markings. Quantitative CT parameters, particularly low-attenuation area percentage (LAA%), correlate strongly with disease severity, symptom burden, and functional decline. HRCT phenotyping allows differentiation of emphysema subtypes with important clinical and prognostic significance. Conclusion: HRCT plays a pivotal role in the early diagnosis, phenotypic classification, and longitudinal assessment of pulmonary emphysema. Integration of qualitative and quantitative HRCT findings with clinical and functional data enhances disease characterization, supports early intervention strategies, and improves patient management and prognostication