Radiologic pattern of disease in patients with severe acute respiratory syndrome: The Toronto experience

Severe acute respiratory syndrome (SARS) is a transmissible febrile respiratory illness caused by a recently discovered coronavirus. Various patterns of disease progression may be observed that have different implications for the prognosis in those affected by SARS. The appearance of the lungs on chest radiographs of patients with this condition may be normal or may include focal airspace opacity or multifocal or diffuse opacities. Thoracic computed tomography (CT) is more sensitive in depicting SARS than is conventional chest radiography, and CT images obtained in patients with normal chest radiographs may show extensive disease and airspace consolidation. However, because the radiologic appearance of SARS is not distinct from that of other diseases that cause lower respiratory tract infection, early identification of SARS will depend in part on the prompt recognition of clusters of cases of febrile respiratory tract illness. To aid in the differential diagnosis and management of SARS, radiologists must be familiar with the typical clinical and histopathologic findings, as well as the radiologic features of the disease.