[Plain CT of venous thromboses of the leg].

In 41 patients with deep vein thrombosis which had been demonstrated by duplex sonography, non-enhanced CT was performed at various levels before phlebography was carried out. Clots judged clinically to be fresh (1-7 days) show predominantly hyperdense thrombus material (60-80 Hu). With longer histories, on the other hand, the majority of thrombi were hypodense (50 Hu or less). Non-enhanced CT provided a rough indication of the age of a thrombus and may aid in deciding whether to use fibrinolysis. Dilatation of veins was found in 80% of the hyperdense early thrombi, but also in the presence of loose and old thrombi. This phenomenon and the presence of perivascular and soft tissue oedema does not indicate the type or age of the thrombus. These findings may be expected to occur also in other vascular areas.