[Pulmonary embolism. The role of computed tomography angiography]

NONINVASIVE PROCEDURE: Helical CT angiography is a noninvasive procedure whose only relative contraindications are renal insufficiency and iodine allergy. MASSIVE PULMONARY EMBOLISM: If a massive pulmonary embolism is suspected, helical CT angiography is the examination of choice because of its high accuracy in detecting proximal thrombi and its safety profile. NON-MASSIVE PULMONARY EMBOLISM: If a non massive pulmonary embolism is suspected, helical CT angiography, because of its high specificity, can be the first examination instead of scintigraphy. If a thrombus is depicted by CT, the diagnosis of pulmonary embolism is confirmed and treatment is started. If no thrombus is visualized by CT, pulmonary embolism can be ruled out in most cases. In case of doubt, another noninvasive procedure should be performed. Angiography should be the exception and seldom is needed.