Do I Need a Chest CT, Chest X-ray, or DLCO Test for COPD?

Important: Seek emergency care immediately if you experience severe or rapidly worsening breathlessness, chest pain, blue or gray lips, confusion, fainting, or the inability to speak in full sentences. Do not wait for an outpatient appointment or a scheduled imaging test.

After a COPD diagnosis is confirmed with spirometry, chest X-rays, chest CT scans, and DLCO tests are not typically needed on a routine, scheduled basis just to monitor the disease ^{[1] [2]}. Spirometry remains the primary test to measure your airflow and track your lung function over time.

Instead, imaging and DLCO are “problem-solving” tests. Doctors order them when symptoms worsen, to look for complications, or to evaluate whether you are a candidate for specific treatments ^[3]. They do not replace spirometry, and a single CT or DLCO result does not determine your overall COPD stage.

Chest X-ray: The Initial Problem-Solver

A chest X-ray is often the first imaging test your doctor will consider if you experience a sudden worsening of symptoms (an exacerbation) or develop new chronic shortness of breath ^{[4] [3]}. However, it is not automatically required for every flare-up.

While an X-ray cannot diagnose COPD, it can look for selected problems that might be causing your symptoms, such as pneumonia or fluid in the lungs ^[5]. It is important to know that a normal chest X-ray does not rule out all dangerous causes of breathlessness, such as a blood clot (pulmonary embolism), early pneumonia, or a heart problem. Your doctor will use the X-ray alongside your physical exam, oxygen levels, and possibly blood tests or an electrocardiogram (ECG) to determine the next steps.

Chest CT Scan: Detailed Structural Views

A computed tomography (CT) scan provides detailed cross-sectional images of your lungs. A chest CT is highly useful for specific situations:

• Evaluating Emphysema: A CT scan can clearly show the extent of emphysema (destruction of the lung’s tiny air sacs) and whether your lungs are hyperinflated ^[6].
• Identifying Overlap Conditions: If you have a chronic, productive cough or frequent infections, a CT scan can check for bronchiectasis (widened, scarred airways that easily trap mucus), though other clinical assessments are also required for a diagnosis ^[7].
• Planning Treatments: If your COPD is severe, a CT scan maps out your lung anatomy to see if you are a candidate for procedures like lung-volume reduction surgery or endobronchial valves (tiny one-way valves placed in the airways via a scope to reduce hyperinflation) ^[8].

Why aren’t CT scans automatic for monitoring?
Medical guidelines do not recommend regular, serial CT scans simply to monitor COPD progression ^{[2] [3]}. Frequent diagnostic CT scans expose you to radiation and often reveal incidental or indeterminate nodules (small spots on the lungs). While most of these spots are benign (harmless), finding them can cause anxiety and may require follow-up scans based on established guidelines to ensure they do not grow ^[9]. Your doctor will order a CT when the expected benefits of the information outweigh these risks.

Note on Lung Cancer Screening: While CTs aren’t used to monitor COPD itself, many people with COPD who have a substantial smoking history may qualify for a separate, routine low-dose CT lung cancer screening ^[9]. This is a specific screening program based on your age and smoking history, not a COPD monitoring test. Ask your doctor if you meet the criteria.

DLCO: Measuring Gas Transfer

DLCO (Diffusing Capacity of the Lungs for Carbon Monoxide) is an advanced breathing test often done in a pulmonary function lab. While standard spirometry measures how much air you can blow out, DLCO measures how well gases transfer from your lung’s air sacs into your bloodstream ^[10].

Your doctor might order a DLCO test to provide clues about:

• Emphysema: Because emphysema destroys the tiny air sacs where gas exchange happens, a lower DLCO score can indicate its presence ^{[11] [12]}.
• Pulmonary Vascular Disease: A low DLCO can also point toward issues with the blood vessels between the heart and lungs, such as pulmonary hypertension (high blood pressure in the lungs) ^{[13] [14]}.
• Disproportionate Symptoms: If you feel incredibly short of breath but your spirometry does not show severe airflow limitation, a low DLCO may provide one clue to explain your exercise limitations ^[15].

DLCO is a nonspecific test—a low result cannot diagnose emphysema or pulmonary hypertension by itself, and further evaluation (like an echocardiogram) is often needed.

The Role of Anemia in DLCO Testing
The DLCO test relies on carbon monoxide binding to hemoglobin (the oxygen-carrying protein in your red blood cells). If you have anemia (low hemoglobin), there is less hemoglobin available to bind to the gas, which can artificially lower your DLCO score ^{[16] [17]}. Your doctor should account for your hemoglobin levels—usually from a recent blood test—when interpreting your DLCO results ^[18].

Summary of Tests