Objective: The purpose of this study was to compare combined CT pulmonary angiography and venography with leg sonography for accuracy and relative efficacy in diagnosis of deep venous thrombosis from the popliteal vein to the common femoral vein.
Subjects and methods: Seventy consecutive patients with clinically suspected pulmonary embolism underwent both combined CT pulmonary angiography and venography and bilateral leg sonography within 24 hr. CT venograms were analyzed independently in a blinded fashion for quality of venous opacification and patency by two observers. CT venography was compared with sonography for femoropopliteal vein thrombosis, and the final assessment based on multiple subjective and objective clinical and imaging criteria was recorded in three categories: 1, CT venography better than sonography; 2, CT venography equivalent to sonography; and 3, sonography better than CT venography.
Results: Sixty-eight patients (97%) had a satisfactory or good quality CT venography examination. Two CT venography studies had false-positive findings due to flow artifacts. Both CT venography and sonography had positive findings for deep venous thrombosis in five patients, and both had negative findings in 63 patients (100% sensitivity, 97% specificity, 100% negative predictive value, and 71% positive predictive value). CT venography was better and more efficacious than sonography (category 1) in 25 patients (36%). CT venography was equivalent to sonography (category 2) in 26 patients (37%), and sonography was better than CT venography (category 3) in 19 patients (27%).
Conclusion: Compared with sonography, CT venography in addition to CT pulmonary angiography is a relatively accurate method for evaluation of femoropopliteal venous thrombosis. Combined CT pulmonary angiography and CT venography may be more efficacious than sonography or two separate examinations in selected patients.