Radiology glossary

Emphysema — What It Means on Your Report

Part of: Chest findings, explained

Full explainer: Emphysema — What It Means on Your Report

The lung's tiny air sacs have been damaged and enlarged — the structural change behind the breathlessness of emphysema. Healthy lungs contain millions of elastic air sacs with thin walls that transfer oxygen; in emphysema those walls break down, the sacs merge into larger, floppier spaces, and the lung loses both surface area and elasticity — like a sponge whose holes have merged into caverns. Smoking is by far the commonest cause, though long-term dust or fume exposure and a rare inherited condition can also produce it. On imaging the lungs look darker and less dense than normal, sometimes with visible holes or blebs, and the chest can appear overexpanded with a flattened diaphragm. Emphysema usually develops gradually over years and is one of the main conditions grouped under COPD. The damage itself cannot be reversed, which is why the finding often prompts a conversation about smoking cessation and lung health — but many people with mild emphysema on a scan have few symptoms, and the report's description is a starting point for evaluation, not a measure of how you feel.

What it means on CT

CT is the definitive test for emphysema: thin slices show the destroyed air sacs directly as areas of abnormally low density — dark holes where lung tissue should be — and reveal the pattern (centered on the airways, as in smoking-related disease, or along the septa). CT quantifies how much lung is involved and shows complications like large blebs or bullae that can rupture. It is also the test that distinguishes emphysema from other causes of breathlessness. Low-dose CT is used for lung screening in eligible smokers.

What radiologists look at next

For emphysema, the radiologist assesses the pattern and extent of low-density lung destruction on CT — whether it clusters around the airways, lines the septa, or involves the whole secondary lobule — and estimates how much of the lungs is affected. They look for complications: bullae or blebs, especially large ones near the lung surface that could rupture, and any superimposed nodules or scarring. The airways are checked for coexisting bronchial wall thickening, since chronic bronchitis often travels with emphysema. Comparison with prior scans tracks progression over years.

Where it commonly shows up

• lungs
• upper lobes
• right lung
• left lung
• chest

Questions to ask your doctor

• How extensive is the emphysema?
• What pattern is it, and what does that suggest about the cause?
• Are there any bullae or complications?
• Do I need breathing tests?
• What can I do to protect my remaining lung function?

Common questions

What causes emphysema?

Smoking is the dominant cause — the irritants in smoke gradually destroy the air sacs' walls over years. Long-term exposure to dust, fumes, or air pollution can contribute, and a rare inherited deficiency (alpha-1 antitrypsin) causes early emphysema in some families. If you smoke, stopping is the single most important step; discuss it with your doctor.

Can emphysema be reversed?

The destroyed air sacs cannot be rebuilt — the structural damage is permanent. But the progression can be slowed dramatically, especially by stopping smoking, and treatments can improve symptoms, exercise capacity, and quality of life. Pulmonary rehabilitation, vaccinations, and prescribed medications all have roles your doctor can explain.

What is the difference between emphysema and COPD?

COPD (chronic obstructive pulmonary disease) is the umbrella clinical diagnosis for persistent airflow limitation, usually from smoking; emphysema is one of the structural lung changes under that umbrella, alongside chronic bronchitis. Doctors diagnose COPD with breathing tests (spirometry), while emphysema is the anatomical description seen on CT. They frequently coexist.

Related conditions

• Pulmonary Nodule — What It Means on Your Report
• Atelectasis — What It Means on Your Report
• Mass — What It Means on Your Report