Using dual-detector helical CT angiography to detect deep venous thrombosis in patients with suspicion of pulmonary embolism: Diagnostic value and additional findings

OBJECTIVE. The purpose of this study was to assess the value of dual-slice helical CT angiography in detecting deep venous thrombosis in patients in w hom acute pulmonary embolism was suspected and to describe the additional e xtrathoracic findings. SUBJECTS AND METHODS. Sixty-five consecutive patients were examined for sus pected pulmonary embolism using helical CT of the chest (2.7-mm collimation : table speed, 7.5 mm/sec; 100-140 ml of contrast medium injected at a rate of 3 mL/sec) followed by CT of the lower limbs (6.5-mm collimation: table speed, 10 mm/sec) without any additional contrast medium injection. Sequent ial scanning of the abdomen was performed using IO-mm collimation and an in terval of 40 mm. Color Doppler sonography of the lower limbs was done withi n 24 hr of CT by two radiologists who were unaware of CT findings. Results of CT venography were compared with those of Doppler sonography and with ph lebography or repeated focalized sonography in cases of discrepancy. RESULTS. Twenty-two patients had pulmonary embolism revealed on chest CT. S ixteen patients had a deep venous thrombosis. Thirteen patients with pulmon ary embolism had a deep venous thrombosis. Three patients with deep venous thrombosis had no pulmonary embolism. Sensitivity and specificity for diagn osing deep venous thrombosis with CT was 93% and 97%. respectively (kappa = 0.88). Additional extrathoracic findings were observed in four patients. CONCLUSION. Combined CT venography with dual-slice scanning is an accurate method to diagnose deep venous thrombosis that may reveal additional imagin g findings in some patients with possible pulmonary embolism.