Imaging of community-acquired pneumonia: Roles of imaging examinations, imaging diagnosis of specific pathogens and discrimination from noninfectious diseases

This article reviews roles of imaging examinations in the management of community-acquired pneumonia (CAP), imaging diagnosis of specific CAP and discrimination between CAP and noninfectious diseases. Chest radiography is usually enough to confirm the diagnosis of CAP, whereas computed tomography is required to suggest specific pathogens and to discriminate from noninfectious diseases. Mycoplasma pneumoniae pneumonia, tuberculosis, Pneumocystis jirovecii pneumonia and some cases of viral pneumonia sometimes show specific imaging findings. Peribronchial nodules, especially tree-in-bud appearance, are fairly specific for infection. Evidences of organization, such as concavity of the opacities, traction bronchiectasis, visualization of air bronchograms over the entire length of the bronchi, or mild parenchymal distortion are suggestive of organizing pneumonia. We will introduce tips to effectively make use of imaging examinations in the management of CAP.