Medical image of the week: pulmonary infarction- the “reverse halo sign”

Abstract

No abstract available. Article truncated at 150 words. Pulmonary infarction is a known complication of pulmonary embolism (PE), a common disorder that results in 100,000-200,000 deaths annually in the United States. Computed tomography (CT) is the first-line modality to assess the pulmonary circulation with the ability to directly the visualize pulmonary emboli as well as pleuro-parenchymal abnormalities. The appearance of a pulmonary infarct varies depending on the degree of ischemic injury in the setting of a dual blood supply to the lung. Infarcts occur more commonly in the periphery of the lung, given, the alternate blood supply by the bronchial arteries, is not as efficient as it is centrally. This location is also favored by the more common occurrence after occlusion of small peripheral arteries of 3 mm or less in caliber. On CT lung infarcts can take the can take the “reverse halo” sign, also known as the “atoll” sign configuration, representing a focal area of decreased …

Keywords

• atoll sign
• reverse halo sign
• pulmonary infarction
• CT scan
• subpleural
• lung
• triangular lesions
• specificity
• cryptogenic organizing pneumonia
• hemorrhage