Comparison Of Test Bolus Techniques And Bolus Tracking Techniques For Dual-energy CT Angiography Of The Lungs

Objective:To compare bolus tracking technique and test bolus technique in second generation dual source CT for pulmonary dual-energy CT angiography in patients with suspected pulmonary embolism.Methods:A total of60patients referred for CTPA for exclusion of PE were included. All examinations were performed on a second generation of dual source CT. These patients were randomized either into a bolus tracking technique group (group B, n=30) or into a test bolus technique group (group T, n=30)。 Test bolus technique was performed using an additional15ml contrast medium injected with a rate of4ml/s during acquisition of a series of dynamic low-dose monitoring scans followed by injection of a saline bolus of15ml using the same flow rate。 A standard dual-energy CTPA was performed after injection of60ml contrast medium followed by35ml saline chaser of4ml/s. Attenuation profiles of different vascular segments (subclavian vein, vena cava, left atrium, pulmonary trunk, S1artery, S10artery) and lung perfusion blood volume value were measured to evaluate the timing techniques. The overall image quality and artifact of "perfusion" map were analyzed by two radiologists.Results:The attenuation of subclavian vein, vena cava, pulmonary trunk, S1artery, S10 artery of group B than the group T(P<0.05).The percentage of pulmonary arteries exceeding optimal attenuation (>250HU) showed that the groups B was lower than the group T(70.0%v.s.96.7%, P<0.05). The values of lung perfusion blood volume of group B was lower than group T (right lung P=0.020, left lung P=0.016, total P=0.016) The image quality of group B was lower than group T (P<0.05), while The artifacts of "perfusion" map of group B was less than the group T (P<0.05).Conclusion:Using60ml contrast medium and35ml saline, test bolus technique can acquire a better arterial enhancement of the CPTA and image quality and the values of lung perfusion blood volume than bolus tracking technique, while it will get more artifacts of "perfusion" map.