Highly sensitive CT scans can detect atypical air sacs, assess lung tissue loss, and pinpoint changes in lung density — key indicators of emphysema.

Emphysema, a severe lung condition involving a loss of elasticity in the air sacs in the lungs, can be challenging to identify through physical exams and X-rays alone.

But modern medical technology offers a powerful diagnostic tool: CT scans. By utilizing X-rays and advanced computer processing, CT scans provide detailed cross-sectional images that can unveil crucial information about the lungs.

Yes, doctors can detect emphysema on a CT (computed tomography) scan.

CT scans can show emphysema-related structural changes in the lungs, such as enlarged air sacs, thinning lung tissue, and areas of lung damage.

Types of CT scans

Doctors can use several types of CT scans to examine emphysema, including the following:

  • High resolution CT (HRCT): HRCT is the most commonly used CT scan for evaluating emphysema, as it provides detailed images of lung structures with high spatial resolution.
  • Low dose CT (LDCT): LDCT is a CT scan that uses a lower radiation dose than conventional CT scans. It can be an effective method for identifying emphysema in its early stages.
  • Quantitative CT (QCT): QCT scans analyze lung tissue density to measure emphysema’s extent and severity. They provide detailed information about the disease and can help monitor its progression and treatment effectiveness.
  • Dual-energy CT (DECT): DECT uses two X-ray energy levels to create CT images. It can provide additional tissue composition information and help distinguish emphysema from other lung conditions or assess coexisting diseases.

Emphysema is identifiable on a CT scan by the appearance of dark or low attenuation areas, indicating reduced X-ray absorption by the affected tissues. These areas indicate overinflation or damage in the air sacs, which are characteristic of emphysema.

Here’s how the three main types of emphysema might appear on a CT scan:

Centrilobular emphysema

Centrilobular emphysema mainly affects the central part of the lung lobules, small structural units within the lungs where gas exchange occurs. It’s common in emphysema caused by smoking.

On a CT scan, centrilobular emphysema shows up as small, round dark areas within the central part of the lung lobules.

Panlobular emphysema

Panlobular emphysema involves damage and enlargement of the entire respiratory unit, including the air sacs, bronchioles, and adjacent structures. It often links with a genetic condition called alpha-1 antitrypsin deficiency.

On a CT scan, it appears as more uniformly distributed areas of low attenuation throughout the lungs.

Paraseptal emphysema

Paraseptal emphysema is less common and primarily affects the small air sacs in the outer regions of the lungs.

One 2015 study suggested that paraseptal emphysema doesn’t typically cause respiratory symptoms on its own, and some experts need more research on its impact.

But with the increasing use of CT scans, doctors can detect the likelihood of this type of emphysema more often in asymptomatic people.

On a CT scan, paraseptal emphysema may appear as thin-walled air sacs next to the outer part of the lungs.

A CT scan can strongly suggest the presence of emphysema, but it can’t confirm it definitively.

The findings on CT scans — which may reveal areas of low attenuation and lung tissue damage — can support a diagnosis of emphysema when combined with:

  • clinical symptoms
  • medical history
  • lung function tests

A definitive confirmation typically requires further testing, such as pulmonary function testing or a lung biopsy, to rule out other lung conditions and provide a more conclusive diagnosis.

If a doctor observes emphysema on a CT scan, it can be a strong indicator of chronic obstructive pulmonary disease (COPD). But it’s important to note that a definitive diagnosis of COPD requires a comprehensive clinical evaluation, including your:

  • medical history
  • physical examination
  • lung function tests
  • symptom assessment

If a doctor confirms emphysema, then it typically indicates the presence of COPD. Emphysema is one of the main subtypes of COPD, along with chronic bronchitis.

A 2018 study found that seeing emphysema on a CT scan may help doctors inform smokers of the chance of death smoking can cause.

The researchers found that smokers with any level of emphysema visible on the scans had a greater chance of dying within 7.4 years than those without visible emphysema. The chance of death increased with the emphysema severity.

CT scans play an important role in the diagnosis and evaluation of emphysema.

CT scans provide detailed images of your lungs, allowing healthcare professionals to identify emphysema-related structural changes, such as enlarged air sacs or lung tissue damage.

If you have shortness of breath or a chronic cough, get medical help as soon as possible. Early detection can help effectively manage emphysema.