Case 48 - Acute versus chronic pulmonary thromboembolism

Summary

Imaging description

Pulmonary emboli, both acute and chronic, appear on CT as intraluminal filling defects that have sharp interfaces [1]. Signs of acute pulmonary embolism include complete occlusion of a vessel with enlargement compared to adjacent vessels, a partial filling defect surrounded by contrast, and a peripheral intraluminal filling defect that forms acute angles with the arterial wall (Figures 48.1 and 48.2) [1, 2]. Occasionally, peripheral wedge-shaped areas, the so-called Hampton’s hump, that may represent infarcts are identified. In contrast, chronic pulmonary emboli are characterized by complete occlusion in a vessel smaller than adjacent vessels, a peripheral crescent-shaped filling defect that forms obtuse angles with the arterial wall, and a web or flap (Figure 48.1) [1]. Other direct signs of chronic pulmonary artery emboli include eccentric thrombus or calcified thrombus (Figure 48.3) [3]. Extensive bronchial or systemic collateral vessels, mosaic perfusion, or calcifications within eccentric vessel thickening are secondary signs of chronic pulmonary emboli (Figure 48.3) [1]. When pulmonary emboli are identified, signs of right heart strain including septal bowing convex toward the left ventricle and reflux of contrast into the inferior vena cava with dilated hepatic veins should be sought [4].