Imaging of acute pulmonary thromboembolism: should spiral computed tomography replace the ventilation-perfusion scan?

For several decades, ventilation-perfusion scintigraphy has been the main imaging modality used in the evaluation of patients with suspected acute pulmonary embolism (PE). Recently, various investigators have suggested that spiral CT pulmonary angiography should replace scintigraphy in the assessment of patients whose symptoms are suggestive of acute PE. This article discusses the role of the various imaging modalities in the diagnosis of acute PE and suggests a diagnostic imaging algorithm based on current evidence in the literature.