Acute pulmonary emboli can manifest as a spectrum of physiological status ranging from an incidental finding to life threatening right heart failure. We discuss the crucial role imaging plays in the accurate and rapid diagnosis. In addition, imaging features are central in assessing the severity of the presentation allowing for appropriate risk stratification and escalation of care. The relative strengths of the various imaging modalities used in the management of chronic thromboembolic pulmonary hypertension are also discussed.