Diagnosis

During the physical exam, your doctor will use a stethoscope to listen carefully to your lungs while you breathe. To distinguish pneumonitis from other lung disorders, you'll likely have one or more of the following tests.

Blood tests

Certain blood tests can be useful for pinpointing a diagnosis.

Imaging tests

Imaging tests are useful because in most cases, pneumonia affects only a small, localized portion of your lungs, while the effects of noninfectious pneumonitis are often spread throughout all five lobes of your lungs.

• Chest X-ray. This painless test causes a small amount of radiation to pass through your chest to produce images of your lungs. X-rays take only a few minutes to perform.
• Computerized tomography (CT). CT scans combine X-ray images taken from many different angles into detailed cross-sectional images. This painless test involves lying on a narrow table that slides into a large, doughnut-shaped machine. CT scans typically take less than 15 minutes to perform. Computerized tomography gives much greater detail of changes in your lungs than what a chest X-ray can provide.

Pulmonary function tests

A test called spirometry measures the amount of air that you're able to inhale and exhale in a specific period of time. Your doctor may also measure how efficiently your lungs transfer gases from the air into the bloodstream during exercise.

Another way to assess how well your lungs are working is to measure the oxygen in your blood with an oximeter — a device that painlessly clamps on your finger.

Bronchoscopy

A bronchoscopy is a procedure that uses a flexible tube threaded down your throat to view your airways and collect samples from your lungs.

During bronchoscopy, your doctor may flush a section of your lung with a saltwater solution to collect lung cells and other materials. This flushing procedure is known as a lavage. Your doctor may also insert a tiny tool through the scope to remove a small sample of cells from the lung tissue for testing.

Surgical lung biopsy

In some cases, your doctor may want to examine larger samples of tissue from several locations in your lungs that cannot be reached via bronchoscopy. A surgical procedure to obtain these samples may be necessary.