 Finally, in a nested study, the investigators aim to compare the clinical usefulness of a complete lower limb compression ultrasonography versus a classical 4-points ultrasonography ultrasonography of the proximal veins in the patients from the ultrasound arm of the study DD-US-hCT. Indeed, preliminary data indicate that complete ultrasound detects a DVT in a higher proportion of patients with PE than proximal ultrasound US and, hence, has the potential for further limiting the requirement for chest imaging in patients with suspected PE. Because finding a distal DVT is of uncertain clinical significance, such a finding will not be reported to the clinicians in charge of the patient and those patients will undergo a helical CT and be treated or not according to the CT result. Outcome measurements will be the number of patients in whom hCT could have been avoided by ruling in the diagnosis of PE in the presence of a distal DVT proportion of patients with both distal DVT on ultrasonography and pulmonary embolism on multi-detector hCT and the number of patients who would have been unduly anticoagulated if considering the presence of a distal DVT in the complete compression ultrasonography proportion of patients with distal DVT on ultrasonography, but without pulmonary embolism on multi-detector hCT, and without a thromboembolic event during the 3 month follow-up. 