What are the indirect CTA findings of pulmonary embolism?
A pulmonary artery with an acute embolus may be slightly enlarged, whereas one with a chronic embolus may be decreased in caliber. Parenchymal findings, such as wedge-shaped peripheral opacities denoting areas of pulmonary infarction, can sometimes be seen as well. Areas of decreased pulmonary perfusion can manifest as wedge-shaped areas of subtle peripheral hypoenhancement. A pleural effusion can sometimes be seen. Signs of right heart strain including right heart dilation and flattening or leftward deviation of the interventricular septum may also be present ( Figure 15-1, B ), and generally portend a worse clinical outcome.