Comparison of test bolus and bolus tracking techniques for dual-energy CT lung perfusion scan / 中华放射学杂志

ABSTRACT

Objective To compare the test bolus technique with the bolus tracking technique for dual-energy CT pulmonary angiography in patients suspected of pulmonary embolism (PE).Methods A total of 60 patients were randomized into 2 groupsbolus tracking technique group (group B,n =30) and test bolus technique group (group T,n =30).A standard dual-energy CT pulmonary angiography (CTPA)was performed after injection of 60 ml contrast medium followed by 35ml saline chaser at a speed of 4 mL/s.Attenuation profiles of different vascular segments (the subclavian vein,superior vena cava,left atrium,pulmonary trunk,S1 and S10 pulmonary artery) and enhancement value of lung parenchyma were measured to evaluate the timing techniques.The overall image quality of CTPA and pulmonary perfusion were analyzed by two radiologists.SPSS 19.0,Student t test,ANOVA test,Chi-Square test,Mann-Whitney U test and Kappa test were used for the statistic analysis.Results The attenuation of the subclavian vein [(1042 ± 639),(2200 ± 724) HU,F =43.196,P =0.001],superior vena cava [(529 ± 237),(904 ± 329)HU,F=25.654,P=0.001],pulmonary trunk [(325 ±112),(383±69)HU,F=5.94,P=0.018],S1 pulmonary artery [(320 ± 118),(385 ±73) HU,F =6.549,P =0.013],S10 pulmonary artery [(307 ± 78),(360 ± 82) HU,F =6.658,P =0.012] in group B were lower than those in group T,while the attenuation of the left atrium in group B was higher than that in group T [(270 ± 53),(219 ± 57)HU,F=12.823,P =0.001].The percentage of pulmonary arteries exceeding optimal attenuation (＞ 250 HU) in groups B was lower than that in group T [n =21 (70.0％),n =29 (96.7％),x2 =5.88,P ＜ 0.05].The enhancement value of pulmonary parenchyma in group B was lower than that in group T (the right lung (29±8)vs(34±8) HU,t=-2.401,P=0.020; the left lung (30±7)vs(36±9)HU,t=-2.493,P=0.016; total (30 ±7)vs(35 ±8) HU,t =-2.495,P =0.016).The image quality of CTPA in group B was poorer than that in group T (U =619.5,P ＜ 0.05,Kappa =0.708),while the artifacts of lung perfusion image in group B was less than that in group T (U =162.5,P ＜ 0.05,Kappa =0.796).Conclusion The test bolus technique has a better image quality of CT pulmonary angiography and a higher lung perfusion blood volume compared with the bolus tracking technique by using 60 ml contrast medium and 35ml saline.