Accurate assessment of pulmonary and extrapulmonary organ involvement in sarcoidosis is one of the great challenges for clinicians. This assessment includes the evaluation of symptoms and of sarcoidosis activity in a specific organ and its functional consequences. In this review, radiological and nuclear techniques to image the inflammatory activity of sarcoidosis are described, in particular (18)F-FDG positron emission tomography/computed tomography. The current use of this technique in clinical practice is explained, particularly in patients with persistent symptoms, stage IV disease and cardiac sarcoidosis.