Helical CT angiography of the pulmonary arteries: Changing the diagnostic approach to patients with suspected pulmunary embolism

Helical (spiral) computed tomography (CT) enables angiogram like images of the pulmonary circulation to be acquired in a single breath hold and has revolutionized the diagnostic work up in patients with suspected pulmonary embolism (PE). The sensitivity and specificity of CT exceed that of scintigraphy, and the accuracy is similar to that of pulmonary arteriography through the segmental arterial level. Unlike other diagnostic tests, CT can also depict clinically significant non-embolic intrathoracic disease, common in elderly patients. This review discusses the technique of helical CT pulmonary arteriography, criteria for interpretation, and its clinical application with particular emphasis on problems common in the geriatric popution. CT has numerous advantages over scintigraphy, and should be used as the initial test in patients with suspected PE, particularly those with associated cardiac or pulmonary disease. If isolated subsegmental thrombi are considered clinically relevant, a negative CT should be followed by an assessment of the deep venous system.