Chronic Pulmonary Embolism

Fig. 1&2: Axial CT image shows a partial thrombus (stars) in the main and proximal left pulmonary artery that forms an obtuse angle with the vessel wall. There is enlarged pulmonary artery and bronchial collaterals (arrows).

Facts

• Some pulmonary emboli do not resolve and form endothelialized fibrosis of pulmonary vascular bed, thought to be due to disturbance in thrombus resolution
• Results: pulmonary HT, cor pulmonale, bronchial hypertrophy

Risks

• Multiple episodes of PE
• Younger age
• Larger perfusion defect
• Idiopathic cause of PE

CT signs

• Complete thrombus with small vascular diameter
• Partial crescent-shaped, eccentric thrombus
• Calcified thrombus
• Web, band
• Pulmonary hypertension
• Collaterals from bronchial arteries
• Mosaic attenuation of the lungs

Reference:
Castaner E, et al. CT diagnosis of chronic pulmonary thromboembolism. Radiographics 2009;29:31-50.