Computed tomographic demonstration of venous thrombosis of different etiologies.

Typical computed tomographic signs of venous thrombosis include the demonstration of the hypodense center (20 to 45 HU) in the involved blood vessel with a hyperdense margin surrounding it. CT represents a reliable method of diagnosis complimentary to that achieved by venography. CT examination allows the visualisation of the proximal end of the thrombus and gives the etiology of the thrombus. Venous thromboses occurring for the first time demonstrate a well defined borderline around the vein with a lack of reaction in the surrounding tissue. On the other hand, recurrent venous thrombosis is characterized by an inhomogenous zone of higher density in the perivascular region. A similar image can be obtained in secondary thrombosis due to inflammatory changes from adjacent tumours. In cases of thrombosis with tumour involvement, the tumour can be demonstrated.