[Scintigraphic criteria for the diagnosis of pulmonary embolism]

The natural history of pulmonary embolism is described, together with the physiopathologic alterations and the clinical manifestations of this disease, correlating these with the various patterns of pulmonary perfusion usually found by lung scintigraphy with 99mTc-MAA in patients with thromboembolic lung disease. By using data found in the literature, the operating characteristics (sensitivity, specificity, and accuracy) and the predictive values of the different scintigraphic patterns, were calculated for populations with different prevalences of pulmonary embolism. It is concluded that perfusion lung scintigraphy is a non-invasive, objective and fast procedure, very sensitive to alterations of the regional blood flow, but that is not specific for embolism. In some cases it can replace pulmonary angiography but in others, its results may indicate the performance of invasive procedures.