Deep venous thrombosis of the lower extremity efficacy of spiral CT venography compared with conventional venography in diagnosis

PURPOSE: To compare the efficacy of spiral computed tomographic (CT) venography with conventional venography in the diagnosis of suspected deep venous thrombosis (DVT). MATERIALS AND METHODS: In a prospective study, 52 consecutive patients with clinically suspected unilateral or bilateral DVT were studied with CT venography and conventional venography. In cases in which conventional venographic findings were inconclusive, color-coded duplex sonography and follow-up examinations were performed to make a final diagnosis. CT venography of both extremities covered a 100-cm section from the ankle to the inferior vena cava (IVC). Contrast material diluted with saline was injected in a dorsal vein of each foot. CT and conventional venography (including color-coded duplex sonography and follow-up findings) were correlated for three venous regions for each patient. RESULTS: Correlation was excellent between CT and conventional venographic findings in the detection of DVT. The sensitivity of CT venography was 100% (confidence interval: 0.92, 1.00), specificity was 96% (confidence interval: 0.84, 0.98), positive predictive value was 91%, and negative predictive value was 100%. CT venography more clearly demonstrated thrombus extension of DVT into the pelvic veins and IVC than conventional venography alone. CONCLUSION: CT venography is a valuable tool in the diagnosis of DVT. Compared with conventional venography, CT requires use of 80% less contrast material.