Combined CT venography and pulmonary angiography in suspected thromboembolic disease: Diagnostic accuracy for deep venous evaluation

OBJECTIVE. Combined CT venography and pulmonary aniography is a new diagnos tic test that evaluates both pulmonary embolism and deep venous thrombosis (DVT) in a single study. Our purpose was to compare the CT venous findings with lower extremity venous sonography. SUBJECTS AND METHODS. Seventy-one consecutive patients with suspected pulmo nary embolism underwent helical CT pulmonary angiography during rapid IV in fusion of contrast medium. Axial scans at 5-cm intervals from the patient's upper calves to the diaphragm were generated 3.5 min after the beginning o f contrast medium injection. CT venous phase images were interpreted prospe ctively and compared with subsequent bilateral lower extremity venous sonog raphy performed within 12 hr. RESULTS. DVT was revealed by CT venous phase images in 19 patients, 12 of w hom also had pulmonary embolism. CT and sonographic findings correlated exa ctly in the femoropopliteal deep venous system, where most pulmonary emboli originate. CT venous phase images also revealed pelvic extension of DVT in six patients and isolated vena cava thrombus in one patient. CONCLUSION. CT venous phase imaging at the time of CT pulmonary angiography is comparable with venous sonography in the evaluation of femoropopliteal DVT. The iliac veins and vena cava, vessels poorly shown on sonography but sometimes the source of significant pulmonary emboli, are also depicted by CT venography.