[Diagnosis of floating venous thrombi by spiral CT phlebography].

PURPOSE

Evaluation by means of spiral CT as to whether or not a thrombus in a proximal deep vein of the leg is floating or adherent to the vessel wall.

METHODS

Local application of contrast agent into an ipsilateral dorsal foot vein and spiral CT were used to examine 16 consecutive cases with deep venous thrombosis proven at conventional venography; in addition, colour Doppler flow imaging was performed.

RESULTS

At conventional venography, 8/16 thrombi appeared to be floating and the remaining 8/16 were adherent to the vessel wall. Spiral-CT showed 15/16 thrombi to be adherent to the vessel wall; the floating thrombus correlated with findings in conventional venography. At colour Doppler flow imaging 3/16 thrombi were considered floating, one of them was discordant to conventional venography. The comparison of conventional venography to spiral-CT demonstrates complete agreement for adherence to vessel wall seen in conventional venography (p = 1,0) and significant discordance in cases with free-floating appearance in conventional venography (p = 0,0002).

CONCLUSION

Adherence of thrombi to the wall of the vessel at conventional venography is in agreement with computed tomography. Conventional venography probably overestimates the prevalence of free floating thrombi.