Name the emphysema subtype (centrilobular, panlobular, paraseptal) and severity, the airway wall thickening and air trapping — and the findings that change care: lung cancer, bronchiectasis, pulmonary artery enlargement, and suitability for valve or volume-reduction therapy.
Orient first
- Centrilobular: upper zones, smokers; panlobular: lower zones, alpha-1 antitrypsin deficiency; paraseptal: subpleural, bullae, pneumothorax risk.
- The Fleischner Society visual grading describes severity (trace to advanced destructive — verify).
- PA:aorta ratio > 1 suggests pulmonary hypertension and predicts exacerbations.
Acquire the study
- Non-contrast CT chest, thin sections, inspiratory and expiratory; quantitative densitometry where available.
The manoeuvre
- Lung window: emphysema subtype and zone; visual severity grade.
- Quantitative: % of lung below −950 HU on inspiration (if software available).
- Airway wall thickening; expiratory air trapping.
- Pulmonary artery diameter in mm and PA:aorta ratio.
- Nodules and masses (lung cancer risk); fissure integrity for endobronchial valves.
What confirms it
- Low-attenuation areas without walls with the subtype and severity stated, with spirometry.
What licenses you to exclude it
- CT emphysema does not define COPD — spirometry does.
The classic misread
- Calling paraseptal bullae cysts.