- Partial or complete obstruction of one or more pulmonary arterial branches by a thrombus.
- More than 90% of all emboli arise from deep vein thromboses.
- Venous stasis
- Vessel wall damage
 Imaging Findings
 Plain film
- Chest radiographs are abnormal in most cases of PE, but the findings are nonspecific and include atelectasis, pleural effusion, parenchymal opacities, and elevation of a hemidiaphragm.
- Classic radiographic findings of pulmonary infarction (infrequently observed)
- Acute PE
- Thrmobus is located centrally within the vascular lumen or occludes the vessel (vessel cutoff sign)
- Commonly causes distention of the involved vessel.
- Chronic PE
- Eccentric and contiguous with the vessel wall
- Reduces the arterial diameter by more than 50%
- Evidence of recanalization within the thrombus
- Arterial web is present
Patient #1: Shortness of breath
Patient #2: Acute RBBB