Severity assessment of acute pulmonary embolism: role of CT angiography

Helical CT has gained wide acceptance in the noninvasive diagnosis of acute pulmonary embolism (APE) and has therefore largely replaced conventional pulmonary angiography as well as ventilation perfusion scan in the work-up of patients suspected of nonsevere pulmonary embolism (PE). Massive PE is life-threatening; its occurrence may require aggressive treatment such as thrombolysis or embolectomy. Identification of patients suffering from major thromboembolic events based solely on clinical grounds may, however, be difficult. Acute right heart failure is the principal cause of circulatory collapse and death for patients with massive PE, and rapid and specific diagnosis and therapy are required in such patients. Bedside echocardiography, a commonly performed first-line examination, demonstrates signs of cor pulmonale, if present, and can identify large central thrombi. However, echocardiography has limitations. In this review, our goal is to discuss the potential role of CT in assessing patients with severe APE. CT evaluation is based on the direct quantification of pulmonary arterial bed obstruction using various scores and the evaluation of morphological heart changes indicating acute cor pulmonale.