Pulmonary Embolism Imaging Techniques Compared
First randomized controlled trial to directly compare computed tomography and ventilation-perfusion scan for ruling out pulmonary embolism
TUESDAY, Dec. 18 (HealthDay News) -- Computed tomography pulmonary angiography (CTPA) is not inferior to ventilation-perfusion (V/Q) scanning in ruling out pulmonary embolism, according to an article in the Dec. 19 issue of the Journal of the American Medical Association.
David R. Anderson, M.D., of Dalhousie University in Halifax, Nova Scotia, and colleagues randomized 1,417 patients with suspected pulmonary embolism based on Wells criteria and D-dimer assay results to undergo either CTPA or V/Q scanning. The primary outcome measured was the rate of subsequent pulmonary embolism or proximal deep vein thrombosis diagnoses in patients in whom pulmonary embolism had been initially excluded.
At the initial presentation, pulmonary embolism was diagnosed in 133 patients in the CTPA group and 101 in the V/Q scan group. Of patients in whom pulmonary embolism was initially excluded, two of 561 patients (0.4 percent) in the CTPA group and six of 611 patients (1 percent) in the V/Q group developed subsequent thromboembolism, a non-significant difference.
Despite the fact that rates of thromboembolic events between groups were similar, "more patients were diagnosed and treated for pulmonary embolism with CTPA than V/Q scanning," write the authors. "Further research is required to confirm whether some pulmonary emboli detected by CTPA may be clinically unimportant, the equivalent of deep vein thrombosis isolated to the calf veins, and not require anticoagulant therapy."