FDG-PET Scan in Sarcoidosis: Clinical and Imaging Indications

Sarcoidosis is an unknown etiology multisystem inflammatory disease in which noncaseating granulomas (a collections of inflammatory cells) form and grow in various organs, involving predominantly lungs, intrathoracic lymph node, skin and eyes. It most commonly affects patients between 20 and 40 years old of age but it could be observed at any age (female predominance; rare in Asians).

The areas of the body usually affected by sarcoidosis are lungs, skin, or lymph nodes; pulmonary and mediastinal involvement is seen in over of 90% of patients. Less commonly eyes, liver, heart, and brain are involved. Any organ, however, can be affected. Early diagnosis of sarcoidosis can be difficult due to few signs and symptoms in its early stages, and when disease does occur, it may mimic other pathologies, and is made up with chest X-ray, Computed Tomography (CT)-High Resolution CT (HRCT), gallium scans. Fluoro-Deoxy Glucose- Positron Emission Tomography (FDG-PET) is another useful tool to assess the extent of disease and has a potential to evaluate the clinical management of patients responding or not to the treatment.

In this review, we would summarize in brief the clinical indications of PDG-PET in sarcoidosis and report the imaging features of the main organs involved in this disease.