Lower limb contrast venography: a modified technique for use in thromboprophylaxis clinical trials for the accurate evaluation of deep vein thrombosis.

Lower limb venography remains the imaging modality of choice for detection of asymptomatic deep vein thrombosis (DVT) in clinical trials of anticoagulant agents. A variety of techniques of venography have been described. Here, we describe a modified technique (the "King's" technique) developed to increase the overall adequacy of identification of lower limb veins and detection of small asymptomatic DVT. Essential elements include proper preparation of patients prior to their arrival in the radiology department, intermittent use of tourniquets to ensure complete and adequate deep vein filling, use of a consistent image acquisition sequence and visualization of all veins in at least two different planes. Use of this technique minimizes technical difficulties, provides improved patient through-put in "busy" fluoroscopy units and, ultimately, improves "off-site" levels of adjudication.