CT-A Outperforms V/Q Scan for Diagnosis of Pulmonary Embolism

Computed tomographic angiography (CT-A) has largely replaced ventilation-perfusion (V/Q) scanning for the diagnosis of pulmonary embolism (PE) because CT-A is easier to obtain and V/Q scans that are categorized as low or intermediate probability present diagnostic uncertainty. In an investigator-blinded, noninferiority trial conducted at five Canadian and U.S. academic tertiary care centers, 1412 patients with positive d-dimer test results or Wells clinical scores ≥4.5 were randomized to undergo V/Q scanning or CT-A in 2001 through 2005. Risk factors for PE were comparable between the two groups.

PE or deep venous thrombosis (DVT) was diagnosed in significantly more patients in the CT-A group than in the V/Q group (19.2% vs. 14.2%). Among pa…