Emphysema Tests and diagnosis

To determine if you have emphysema, your doctor is likely to recommend certain tests, including:

• Pulmonary function tests (PFTs). These noninvasive tests can detect emphysema before you have symptoms. They measure how much air your lungs can hold and the flow of air in and out of your lungs. They can also measure the amount of gases exchanged across the membrane between your alveolar wall and capillary membrane. During the test, you're usually asked to blow into a simple instrument called a spirometer. PFTs may be done before and after the use of inhaled medications to test your response to them. If you're a smoker or a former smoker, ask your doctor about taking this test, even if you don't have symptoms of COPD.
• Chest X-ray. You're likely to have a chest X-ray to help rule out other lung problems rather than to diagnose emphysema — because even in the advanced stages of the disease, chest X-rays are often normal.
• Arterial blood gases analysis. These blood tests measure how well your lungs transfer oxygen to your bloodstream and how effectively they remove carbon dioxide.
• Pulse oximetry. This test involves the use of a small device that attaches to your fingertip. The oximeter measures the amount of oxygen in your blood differently from the way it's measured in a blood gas analysis. To help determine whether you need supplemental oxygen, the test may be performed at rest, during exercise and overnight.
• Sputum examination. Analysis of cells in sputum can help determine the cause of some lung problems.
• Computerized tomography (CT) scan. A CT scan allows your doctor to see your organs in two-dimensional images or "slices." Split-second computer processing creates these images as a series of very thin X-ray beams are passed through your body. A CT scan can detect emphysema sooner than an ordinary chest X-ray can, but it can't assess the severity of emphysema as accurately as can a pulmonary function test.

Additionally, researchers are studying whether magnetic resonance imaging (MRI) could detect emphysema even before signs and symptoms appear.