Methods: Color Doppler ultrasound and MDCT direct venography examinations were performed in 30 patients (21 males, 9 females; mean age 48 years; range 21 to 80 years) with clinical suspicion of DVT. The MDCT direct venography was performed within 24 hours, after the CDUS examination.

Results: Color Doppler ultrasound was diagnostic in all of the lower limb veins (240 venous segments), while non-diagnostic in 68 out of 150 venous segments at the pelvic region. Color Doppler ultrasound identified DVT in 13 segments, and MDCT direct venography identified DVT in 21 venous segments at the pelvic region. All of the lower limb DVT’s were depicted both by CDUS and direct MDCT venography, except for one calf muscular vein thrombosis which was detected by CDUS. Multidetector computed tomography direct venography showed false positive thrombosis in five venous segments (4 femoral vein, 1 popliteal vein) and a pseudotrombosis appearance due to the flow phenomenon in one venous segment (common iliac vein). Partially recanalized low flow in chronic DVT patients could also be demonstrated on MDCT direct venography.

Conclusion: Multidetector computed tomography direct venography is more reliable than color Doppler US in diagnosis of DVT of the iliac veins and inferior vena cava. However, false positive thrombosis on MDCT direct venography can be seen distal to an occluded venous segment similar to the conventional venography.