The value of 64-detector row computed tomography for the exclusion of pulmonary embolism

Recently, a diagnostic strategy using a clinical decision rule, D-dimer testing and spiral computed tomography (CT) was found to be effective in the evaluation of patients with clinically suspected pulmonary embolism (PE). However, the rate of venous thromboembolic complications in the three-month follow-up of patients with negative CT was still substantial and included fatal events. It was the objective to evaluate the safety of withholding anticoagulants after a normal 64-detector row CT (64-DCT) scan from a cohort of patients with suspected PE. A total of 545 consecutive patients with clinically suspected first episode of PE and either likely pre-test probability of PE (using the simplified Wells score) or unlikely pre-test probability in combination with a positive D-dimer underwent a 64-DCT. 64-DCT scanning was inconclusive in nine patients (1.6%), confirmed the presence of PE in 169 (31%), and ruled out the diagnosis in the remaining 367. During the three-month follow-up of the 367 patients one developed symptomatic distal deep-vein thrombosis (0.27%; 95%CI, 0.0 to 1.51%) and none developed PE (0 %; 95%CI, 0 to 1.0%). We conclude that 64-DCT scanning has the potential to safely exclude the presence of PE virtually in all patients presenting with clinical suspicion of this clinical disorder.