This issue of Radiologic Clinics will focus on the essentials of thoracic imaging. Topics include lung cancer screening and staging systems, radiation dose techniques, nodule characterization, PET/CT in the thorax, MDCT and MR evaluation of thoracic aorta, pulmonary emboli and perfusion imaging, interstital pneumonias, emphysema and airway imaging, post-operative chest, and thoracic infections in the immunocompromised host.