The purpose of this study was to assess the usefulness of combined MDCT venography , including below-the-knee veins and pulmonary angiography , in suspected thromboembolic disease.

one hundred and thirty-two patients with possible deep vein thrombosis (DVT) and/or pulmonary embolism (PE) were enrolled in this study. CT venography was performed using an MDCT with four detector arrays. The scans were obtained with 1.25x1.25- mm collimation and pitch 6 for the chest, with 5x 5-mm collimation and pitch 3 for the IVC and the iliac veins, with 2.5x2.5-mm collimation and pitch 6 for the femoral veins, and with 1.25x1.25-mm collimation and pitch 6 for the below-the-knee veins. One hundred ml contrast material was injected into 130 patients (370mgI/ml; n=119, 350mgI/ml; n=1, 300 mgI/ml; n=12), and 120ml of 370mgL/ml contrast material was injected into two patients. The venous system was scanned three and a half minutes after injection.
Criteria for the diagnosis of DVT and PE were intraluminal filling defect or localized nonopacification of a vascular lumen. All images were evaluated on a monitor at a workstation. All CT scans were initially evaluated by one of three radiologists. Subsequently, the second radiologist independently assessed the images. Discrepancies were resolved by consensus to establish the final interpretation.

Two patients were eliminated because severe artifacts from an artificial joint interfered with the evaluation. A total of 47 patients had DVT and/or PE, including 14 patients with DVT alone, three patients PE alone, and 30 patients with both. Although they were principally distributed above-the-knee veins in 31 patients, the MDCT venography demonstrated that these lesions were restricted to below-the-knee veins in 12 patients. Of these 12 patients, four had only soleal vein thrombosis. Isolated soleal vein thrombosis was found in two patients.

Complete lower extremity venous evaluation including the below-the-knee veins can improve the diagnostic ability for patients with suspected thromboembolic disease. The prevalence of isolated below-the-knee vein thrombosis was higher than that of the previous report by US evaluation.