Imaging in sarcoidosis.

Sarcoidosis is a multisystemic granulomatous disease of unknown etiology that may involve virtually any organ. Pulmonary involvement predominates, but sarcoidosis can involve multiple organs, with or without concomitant lung involvement. Aberrations on chest radiographs are present in more than 90% of patients with sarcoidosis. Bilateral hilar lymphadenopathy, with or without lung parenchymal infiltrates, is typical but a wide range of chest radiographic patterns may be observed. This article discusses the characteristic chest radiographic features of sarcoidosis and the prognostic value of the radiographic staging classification as espoused by Scadding more than 4 decades ago. Thin-section high-resolution computed tomographic (HRCT) scans more clearly elucidate the intrathoracic lesions observed in sarcoidosis and may discriminate active inflammation from end-stage fibrosis. Although HRCT is not necessary to manage all cases of sarcoidosis, HRCT may be invaluable in SELECTED patients with stage II or III sarcoidosis to discriminate alveolitis (which may be amenable to therapy) from fibrosis. Additionally, radionuclide techniques may have a role in extrapulmonary sarcoidosis (particularly when central nervous system or cardiac involvement is suspected). We review the salient features and role of magnetic resonance imaging and diverse radionuclide techniques to diagnose or follow selected cases of extrapulmonary sarcoidosis.