A Study of CT Venography after Pulmonary CT Angiography in Diagnosis of Deep Venous Thrombosis

Objective:To determine the location and extension of deep venous thrombosis on CT venography after pulmonary CT angiography in patients clinically suspected of having pulmonary embolism and to compare the accuracy of CT venography with lower-extremity venography.Methods:Deep venous images were acquired after pulmonary CT angiography in 19 patients clinically suspected of having pulmonary embolism.11 women,8 men;aged 38～73,mean age,55.5 years.The scan extension of pulmonary CT angiography goes from the diaphragm to the aortic arch and that of deep venography,from the diaphragm to the upper calves.The presence and location of deep venous thrombosis were analyzed and compared with those of lower-extremity venography in 15 patients. Results:Satisfactory CT images of deep venography were obtained in all 19 patients except one.12 cases had pulmonary embolism and/or deep venous thrombosis,in which 1 patient showed pulmonary embolism alone,5 patients,deep venous thrombosis alone,and 6 patients had both.Among 11 patients with deep venous thrombosis,4 cases of thrombus proximal to the femoral vein were not detected by lower-extremity venography,whereas 10 patients showed femoropopliteal deep venous thrombosis by lower-extremity venography,9 cases were detected by CT venography.Conclusion:Pulmonary CT angiography can define pulmonary embolism and other non-embolic pulmonary diseases.The combination of CT venography with pulmonary angiography can also accurately depict pelvic,abdominal and lower-extremity thrombi.