Pulmonary vascular imaging.

A wide range of pulmonary vascular imaging techniques are available for the diagnostic evaluation of patients with suspected pulmonary vascular disease. The characteristics of any "ideal" technique would include high sensitivity and specificity, safety, simplicity, and sequential applicability. To date, no single technique meets these ideal characteristics. Conventional pulmonary angiography remains the "gold standard" for the diagnosis of acute thromboembolic disease despite the introduction of newer techniques such as digital subtraction angiography and magnetic resonance imaging. Improved noninvasive lower extremity venous testing methods, particularly impedance plethysmography, and ventilation-perfusion scanning can play significant roles in the noninvasive diagnosis of acute pulmonary emboli when properly applied. Ventilation-perfusion scanning may also be useful as a screening test to differentiate possible primary pulmonary hypertension from chronic thromboembolic pulmonary hypertension. And, finally, angioscopy may be a useful adjunctive technique to detect chronic thromboembolic disease and determine operability. Optimal clinical decision-making, however, will continue to require the proper interpretation of adjunctive information obtained from the less-invasive techniques, applied with an understanding of the natural history of the various forms of pulmonary vascular disease and with a knowledge of the capabilities and shortcomings of the individual techniques.