 Therefore, the investigators plan to compare the efficacy and cost-effectiveness of two distinct diagnostic strategies for suspected pulmonary embolism in emergency center patents in a non-inferiority trial. The strategies are: 1 an algorithm based on clinical assessment, D-dimer and multi-detector hCT DD-hCT; and 2 a previously validated strategy that includes lower limb compression DD-US-hCT. The main outcome will be the rate of thromboembolic events during a formal 3-month follow-up in patients not anticoagulated on the basis of a PE ruled out by the diagnostic criteria in each study arm. A secondary outcome will be the costs of diagnosis in each study arm, including the costs of suspected andor confirmed thromboembolic events during follow-up. 