Detection of Venous Emboli Using Doppler Ultrasound

ObjectivesTo detect emboli in the venous system using a Doppler ultrasound device with embolism detecting software.MethodsPulmonary embolism (PE) was induced by injecting thrombus through the iliac vein of castrated swine under general anaesthesia. Data recorded from the Doppler system were analysed for high intensity transient signals (HITS) using receiver operating characteristic curves. Four different thrombi (5 or 10 mm long and 3 or 5 mm in diameter) were then injected to assess the quantitative analysis.ResultsThrombus could be detected in the venous system by the Doppler ultrasound device with an embolism detecting function. Appropriate confidence level was 60%. If thrombus were assumed to travel at the maximum flow rate (30 cm/s) in the inferior vena cava, the estimated embolism size was 10.4 S.D. 2.8 mm for 3 mm and 10.8 S.D. 4.9 mm for 5 mm, both of which were close to 10 mm.ConclusionThrombi could be detected as high intensity transient signals in the venous system. The appropriate confidence level was 60%. The size of emboli can be estimated if they are more than 3 mm in diameter when the venous flow rate is 30 cm/s or less. Our results suggest that it may be possible to detect emboli in the subclavian vein, axillary vein or inferior vena cava in clinical cases.