Volumetric HRCT in Stable COPD Patients.

Background and Rationale: Chronic Obstructive Pulmonary Disease (COPD) is characterized by persistent respiratory symptoms (such as dyspnea, cough, and sputum production) resulting from airway and/or alveolar abnormalities that cause progressive airflow obstruction. While irreversible airflow obstruction (post-bronchodilator FEV1/FVC \< 0.70) measured by spirometry confirms the diagnosis, global spirometric tests lack the spatial resolution required to assess regional parenchymal destruction, emphysema distribution, or peripheral air trapping. Volumetric High-Resolution Computed Tomography (HRCT) enables detailed, three-dimensional quantitative assessment of lung parenchyma and structural alterations in COPD. Study Objectives: To quantify emphysema extent, air trapping, and airway wall thickness using volumetric HRCT. To assess the relationship between quantitative volumetric HRCT findings and clinical measures of COPD severity. Methods and Procedures: This cross-sectional observational study is conducted at Mansoura University Hospital (smoking clinic and chest disease general clinic) under ethics approval code MS.25.02.3101. Enrolled participants include patients with stable COPD diagnosed according to GOLD guidelines. All participants undergo the following assessments: Clinical Evaluation: Comprehensive history taking (symptoms, smoking status), physical examination, and mMRC Dyspnea Scale grading. Pulmonary Function Testing \& Lung Volumes: Spirometry (FEV1, FVC, FEV1/FVC, MMEF), 6-Minute Walk Test (6MWT), and lung volume measurements (RV, TLC, RV/TLC%). Laboratory Tests: Complete Blood Count (CBC) with calculation of Neutrophil-to-Lymphocyte Ratio (NLR) and Platelet-to-Lymphocyte Ratio (PLR), and Arterial Blood Gas (ABG) analysis. HRCT Imaging Protocol: Multidetector HRCT (minimum 64-slice, ≤1,5 mm slice thickness, 512x512 matrix) performed during full inspiratory breath-hold (with optional expiratory scanning for air trapping evaluation). Dedicated high-resolution algorithms and window settings are applied to quantify parenchymal and bronchial changes. nd bronchial changes.