张燕*　金征宇*　张竹华*　陆慰萱#　赵文敏*　王坛*　张云庆*<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

中国医学科学院中国协和医科大学，北京 100730

*北京协和医院放射科

#北京协和医院呼吸内科

Combined Multi-slice CT Venography and Pulmonary Angiography: Optimization of the Acquisition Protocol

Yan Zhang”, Zhang-Yu Jin”, Zhu-hua Zhang”, Wei-xuan Lu#, Wen-min Zhao”, Yun Wang”, Yun-qing Zhang”

*Ddepartment of Raditology, (#Department of Respiratory Medicine) Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China

ABSTRACT

Objective：To evaluate the enhancement degree of lower extremity deep veins and pulmonary arteries by using lesser contrast material and a biphasic injection protocol in the examination of combined CT venography and pulmonary angiography (CTVPA).

Methods：50 CTVPA examinations were done in 48 patients of clinically suspected pulmonary embolism.20 examinations (group 1) were performed by using 150ml contrast material (300mg l/ml) with a flow rate of 4ml/s. the other 30examinations(group 2) were performed by using 120mo contrast material with biphasic injection protocol: first phase, 50ml with a flow rate of 4ml/s; internal iliac vein, common femoral vein, superficial femoral vein, deep femoral vein and popliteal vein on the CT venography. The attenuation values in the pulmonary trunk, apical segmental arteries of the bilateral upper lobe, posterior segmental arteries of the bilateral lower lobe and ascending aorta were also measured at the same time. The artifacts in the superior vena cava were scored as follows: O point, the artifacts were not exist; 1 point, a little artifacts exist; 2 points, significant artifacts exist and affect the demonstration of right pulmonary artery and right upper lobe pulmonary artery.

Results：Very good enhancement was obtained in veins mentioned above in both groups with mean attenuation values of 98～117HU without significant difference (P>0.05).High degree enhancement was also obtained in pulmonary arteries in both group with mean attenuation of 323～420HU, which was signify-cantly higher than that of ascending aorta in both groups(198±56.7HU,233±55.54HU, respectively). The scores of the artifacts in the superior vena cava were 1.05,0.67 respectively for the two groups without significant difference between them. But, the proportion of O point in group 1 is significantly lower than in group 2, which is 25%(5/20),53.33%(16/30)respectively(P=0.047).

Conclusion：Using 120ml contrast material with biphasic injection protocol can obtain the same enhancement degree in both the lower extremity deep vein and the pulmonary artery as that using 150ml contrast materials, and have some degree of effect on the reduction of superior vena cava artifacts. So, the biphasic injection protocol using 120ml contrast material can be employed in routine CTVPA examinations.

Key words：Multi-slice CT; Angiography; Contrast enhancement; CT venography; Pulmonary embolism