The clinical application of combined dual-energy CT pulmonary angiography and indirect venography

Objective To assess the usefulness of combined dual-energy CT pulmonary angiography (DE-CTPA) and indirect CT venography (CTV) in the diagnosis of venous thromboembolism (VTE) . Methods Forty-nine patients with leg swelling suspected of pulmonary embolism (PE) underwent both DE-CTPA combined with CTV and lower extremity venous ultrasound (US) in 1—2 days prior to CT.Image quality of CTPA and dual energy lung perfusion image (DEPI) was rated using a 5-point scale and the coherence between CTPA and DEPI was analyzed by Kap pa statistics.The ability of CTV and US in the diagnosis of deep venous thrombosis (DVT) was compared by Chi-square test. Results Twenty-nine of 49 patients were identified with PE by DE-CTPA,including 28 patients identified by CTPA and one more by DEPI,and 21 patients were found to have both PE and DVT.Both DE-CTPA and DEPI had positive findings for pulmonary embolism in 19 patients and both had negative findings in 18 patients.There was a moderate agreement between DEPI and DE-CTPA in the assessment of PE (Kappavalue=0.7534).Thirty-eight patients with DVT were identified by US,while 35 patients were identified by CTV.Among the 35 patients with DVT identified by CTV,pelvic veins were involved in 25 patients,while the inferior vena cava was involved in 3 patients.There was no significant difference between CTV and US in the diagnosis of DVT (P=0.625).The detection rate of VTE with DE-CTPA combining CTV was 30.6% higher than that with CTPA alone. Conclusions The combined DE-CTPA and CTV achieves“one-stop”examination.It not only provides evaluation of PE and DVT and increases detection of VTE,but also depicts perfusion defect of pulmonary parenchyma that corresponds to PE. Key words: Pulmonary embolism; Venous thrombosis; Lower extremity; Phlebography; Tomography,X-ray computed