EKG-gated digital subtraction angiography in the detection of pulmonary emboli

Detection of pulmonary emboli was investigated using electrocardiographically gated (EKG-gated) intravenous digital subtraction angiography (DSA) in 6 anesthetized and paralyzed dogs. Six autologous blood clots were introduced into the internal jugular vein of each dog and both conventional pulmonary angiography and EKG-gated DSA performed in frontal and oblique projections. When two observers scored any definite or equivocal embolus as positive, sensitivity was 82.1% for one and 92.9% for the other; the respective positive predictive values (PPV) were 88.5% and 65%. When only definite emboli were considered positive, sensitivity was 75% for one observer and 71.4% for the other; PPV was 100% for both. The authors conclude that DSA can demonstrate individual emboli with good sensitivity and excellent precision. If several emboli are present, EKG-gated DSA should prove highly accurate; however, care must be taken because overinterpretation is more likely with DSA than with conventional pulmonary angiography.