OBJECTIVE. The purpose of this study was to compare the clinical value of CT venography (CTV) after MDCT angiography (CTA) with venous compression sonography for the diagnosis of venous thromboembolism (VTE). The Prospective Investigation of Pulmonary Embolism Diagnosis II (PIOPED II) showed that lower extremity imaging detects about 7% more patients requiring anticoagulation than CTA alone. SUBJECTS AND METHODS. PIOPED II was a prospective multicenter study investigating the accuracy of CTA alone and CTA and CTV together. A composite reference standard was used to confirm, or rule out, pulmonary embolus. Adequate quality CTV and sonographic images were obtained in 711 patients. RESULTS. There was 95.5% concordance between CTV and sonography for the diagnosis or exclusion of deep venous thrombosis (DVT); the kappa statistic was 0.809. The sensitivity and specificity of combined CTA and CTV were equivalent to those of combined CTA and sonography. Diagnostic results in subgroups, including patients with signs or symptoms of DVT, asymptomatic patients, and patients with a history of DVT, were similar whether CTV or sonography was used. Patients with signs or symptoms of DVT were eight times more likely to have DVT, and patients with a history of DVT were twice as likely to have positive findings. CONCLUSION. CTV and sonography showed similar results in diagnosing or excluding DVT. The incidence of positive studies in patients without signs, symptoms, or history of DVT is low. In terms of clinical significance, CT venography and lower extremity sonography yield equivalent diagnostic results; the incidence of positive studies in patients without signs, symptoms, or history of DVT is low; thus the choice of imaging technique can be made on the basis of safety, expense, and time constraints.
- CT venography
- Deep venous thrombosis
- Lower extremity Doppler sonography
- Pulmonary embolus