Sarcoidosis is a rare inflammatory disease that may affect any part of the body. The condition is associated with clumps of immune cells, called granulomas, forming in the organs, disrupting their normal function and potentially causing permanent damage.

The most commonly affected organ is the lungs, with around 90 percent of sarcoidosis patients being diagnosed with pulmonary sarcoidosis.

A diagnosis of pulmonary sarcoidosis may require multiple tests to rule out other conditions. Typically, these include one or more imaging tests performed on the lungs to confirm the presence of granulomas or other abnormalities.

Chest X-ray

This type of imaging test uses X-rays directed at the chest to produce an image of the lungs and the surrounding area. It can reveal abnormalities, such as inflamed (or enlarged) lymph nodes or the presence of granulomas. It is also called chest radiography.

Computed tomography (CT) scan

A CT scan also uses X-rays, but with the addition of computer technology, it can produce more detailed images. It has further been improved with the advent of high-resolution computed tomography (HRCT) scans. CT scans are becoming a more common practice for diagnosis, and may more accurately help assign a stage to the level of pulmonary sarcoidosis in a patient.


Bronchoscopy allows the doctor to see directly inside the lungs. It involves passing a thin and flexible tube, called a bronchoscope, through the mouth or nose and down the windpipe. The bronchoscope has a small camera and fiber optic light attached to it so that the doctor can inspect the lungs.

Bronchoscopy can also be used to take a lung biopsy, which involves removing a small piece of lung tissue for testing.

Positron emission tomography (PET) scan

A PET scan involves the injection of a small amount of a radioactive substance called a tracer that will target areas of inflammation or where granulomas have collected. A scanner detects the areas the tracer has targeted, building a detailed three-dimensional image showing the location and intensity of the abnormality.

This technique is not specific to the lungs or to sarcoidosis-related inflammation, so it will also pick up on other abnormalities. It is less commonly used to diagnose pulmonary sarcoidosis, or is used in combination with other tests.

Other imaging tests

Rarely, other imaging tests, such as magnetic resonance imaging (MRI), may be carried out to diagnose sarcoidosis, but this is more commonly used to view organs other than the lungs.

