Volumetric HRCT in Stable COPD Patients.

The Role of Volumetric High-Resolution Computed Tomography (HRCT) of the Chest in the Assessment of Patients With Stable Chronic Obstructive Pulmonary Disease (COPD)

This study evaluates the role of volumetric high-resolution computed tomography (HRCT) of the chest in assessing patients with stable chronic obstructive pulmonary disease (COPD). COPD is a heterogeneous lung condition characterized by chronic pulmonary symptoms, structural airway/alveolar changes, and progressive airflow limitation. While spirometry provides a global assessment of lung function, it cannot localize or fully characterize specific structural abnormalities. Volumetric HRCT allows for detailed, quantitative imaging of lung parenchyma, emphysema extent, air trapping, and airway wall thickness. The primary objective of this cross-sectional observational study is to quantify emphysema, air trapping, and bronchial wall thickness in patients with stable COPD and to evaluate the relationship between these volumetric HRCT findings and clinical measures of disease severity. By identifying objective imaging parameters, this study aims to improve patient evaluation, disease staging, and clinical management.

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.

Inclusion Criteria:Patients with stable chronic obstructive pulmonary disease (COPD)

Diagnosed according to GOLD criteria (post-bronchodilator FEV1/FVC < 0.70)

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Exclusion Criteria:

1. Patient in exacerbation defined as change in the patient's baseline dyspnea, cough, and/or sputum beyond normal day-to-day variations within 14 days . (Ko, Fanny W., et al 2016)

2. Connective tissue disease .

3. Previously diagnosed Interstitial lung disease

4. Contraindication to PFT According to ATS (Stanojevic S., et al 2021)

   • Recent Myocardial Infarction Within 1 week
   • Blood Pressure Instability Severe hypertension or systemic hypotension
   • Arrhythmias Significant, uncontrolled atrial or ventricular arrhythmias
   • Decompensated heart failure
   • Pulmonary Circulation Issues: Uncontrolled pulmonary hypertension, acute cor pulmonale, or clinically unstable pulmonary embolism
   • History of Syncope Loss of consciousness related to coughing or forced expiration
   • Cerebral Aneurysm
   • Recent Brain Surgery: Within 4 weeks
   • Concussion: Recent concussion with prolonged symptoms
   • Eye Surgery: Recent eye surgery within 1 week
   • Pneumothorax: Active or untreated pneumothorax Recent Thoracic Surgery: Within 4 weeks Recent Abdominal Surgery: Within 4 weeks Late-Term Pregnancy

5. Contraindicatins of 6MWT according to ATS :

Absolute contraindications

• Unstable Angina Experienced during the previous 1 month.

• Recent Myocardial Infarction : Within the previous 1 month. Relative contraindications

• Resting Tachycardia: Resting heart rate > 120{ bpm}.

• Severe Uncontrolled Hypertension:

  • Systolic Blood Pressure > 180{ mmHg}
  • Diastolic Blood Pressure > 100{ mmHg}

• Symptomatic/Severe Cardiac Conditions: High-degree atrioventricular (AV) block, hypertrophic cardiomyopathy, or symptomatic severe aortic stenosis.