Update on diagnostic strategies of pulmonary embolism.
Acute pulmonary embolism is a frequent disease with non-specific findings, high mortality, and multiple therapeutic options. A definitive diagnosis must be established by accurate, non-invasive, easily performed, cost-effective, and widely available imaging modalities. Conventional diagnostic strategies have relied on ventilation-perfusion scintigraphy complemented by venous imaging. If the results are inconclusive, pulmonary angiography, which is regarded as the gold standard, is to be performed. Recently, marked improvements in CT and MRI and shortcomings of scintigraphy led to an update of the diagnostic strategy. Spiral CT is successfully employed as a second-line procedure to clarify indeterminate scintigraphic results avoiding pulmonary angiography. It can also be used as a first-line screening tool if service and expertise is provided. Venous imaging is indicated if CT is inconclusive. The MRI technique can be applied as an alternative second-line test if spiral CT is not available or is contraindicated. It has the greatest potential for further developments and refinements. Echocardiography should be used as a first-line bedside examination in critical patients. If inconclusive stabilized patients undergo spiral CT, unstable patients should be referred for pulmonary angiography. Chronic thromboembolic pulmonary hypertension is a rare sequela of acute pulmonary embolism which can be cured surgically. Morphology, complications, and differential diagnoses are better illustrated by spiral CT and MRA, whereas invasive acquisition of hemodynamic data is the sole advantage of angiography.