Evaluation of the Venous System of the Lower Extremity by Three Dimensional Spiral-CT-Venography

There are two common diseases involving the venous system of the lower extremity. One is deep vein thrombosis (DVT) and the other is venous insufficiency resulting in varicose veins.

Until now, the primary imaging modality for the lower extremity venous system is duplex and/or color Doppler sonography because of its diagnostic performance, capability to evaluate hemodynamic information, convenience and availability. However, it is operator-dependent and has inherent limitations to evaluate deep-seated pelvic veins. Overall picture of the disease status cannot be depicted with ultrasound examinations.

We have established volume data acquisition and three-dimensional (3D) post-processing techniques for spiral CT venography (CTV) of the lower extremity and evaluated their usefulness in 200 patients with suspected DVT or venous insufficiency. The quality of CTV images in depicting deep, superficial and perforating veins are good enough for the diagnosis in 95% of patients. Volume-rendered images after noise reduction process clearly depicts all of the major superficial and meaningful varicose and perforating veins. 3D display functions for real-time interactive adjustment of opacity transfer function and real-time interactive correlation between 3-D volume-rendered images and 2-D images are necessary for rapid and accurate localization of perforating veins.

The primary advantages of CTV over Doppler ultrasound are the objective and comprehensive morphologic evaluation of the entire venous system (pelvic, superficial and deep venous system) and possible 3D overview of the disease. CTV is superior to Doppler ultrasound in the evaluation of the extent and underlying anatomic problems of acute DVT, which are valuable information for transcatheter thrombolysis. In varicose veins, the primary cause of venous insufficiency and dilated perforators in unusual location can be accurately evaluated. Vascular surgeons reported high satisfaction of themselves and their patients. Despite of absent hemodynamic information, CTV can be an excellent complementary examination for DVT and varicose veins in the lower extremity.

Lernziele:

Diagnosis of Deep Venous Thrombosis