A COMPARISON OF PULMONARY ANGIOGRAPHY, DIGITAL SUBTRACTION ANGIOGRAPHY, AND 99mTc-DTPA/MAA VENTILATION-PERFUSION SCINTIGRAPHY FOR DETECTION OF EXPERIMENTAL PULMONARY EMBOLI IN THE DOG

The abilities of pulmonary angiography, digital subtraction angiography and ventilation-perfusion scintigraphy (V/Q) to detect experimental acute pulmonary emboli were evaluated in a group of 18 research dogs. Emboli were produced by forceful intravenous injection of clotted blood. In five dogs, emboli were labeled with thallium-201 prior to reinjection so that embolus position could be confirmed on scintigraphic studies.
Studies were independently reviewed by three observers. Results were combined so that the relative sensitivity, specificity, and accuracy of each imaging technique could be compared using chi-square and receiver-operating characteristic curve analysis. Digital subtraction angiography and V/Q studies proved to be significantly more specific and accurate than conventional pulmonary angiography. V/Q studies were uniformly of good to excellent quality while the quality of digital subtraction angiography studies was variable depending on the adverse effects of respiratory motion. It was concluded that ventilation-perfusion scintigraphy is the best available method to screen dogs suspected of having pulmonary thromboembolism.