Imaging of Sarcoidosis

The diagnostic imaging contributes significantly to the diagnosis and management of sarcoidosis. Imaging techniques are widely employed in the assessment of thoracic and extra-thoracic involvement from sarcoidosis. For the diagnosis of sarcoidosis, chest radiograph has been the cornerstone of sarcoidosis since 1961, when Scadding proposed a standardized staging system. Currently, computed tomography (CT) represents the reference standard for the assessment of both mediastinal lymph nodes and pulmonary findings. In particular, high-resolution computed tomography (HRCT) is more accurate compared to chest radiography for the detection of subtle parenchymal involvement, and provides comprehensive overview of anatomical detail and abnormalities of lung structures. Notably, HRCT allows for accurate differentiation between reversible and irreversible lung disease, which is cornerstone of prognostication. Radionuclide imaging (gallium-67 and ¹⁸F-fluorodeoxyglucose) provides information about activity of the disease and is also useful for diagnostic workup of patients with unexplained persistent disabling symptoms. Magnetic resonance is sensitive for the detection of sarcoidosis granulomata within myocardium, thus providing detailed roadmap for biopsy. For the management of sarcoidosis, CT is of paramount importance in the detection and differential of most common complications, such as vascular disease and suspicious nodular lesions. Conversely, the role of CT in the follow-up of asymptomatic subjects is still under debate. This review focuses on the role of diagnostic imaging in the diagnosis and follow-up of sarcoidosis.