[Imaging of the lower limb veins: when and how?].

Evaluation for possible lower limb deep venous thrombosis (DVT) is a very frequently requested examination. In France, imaging diagnosis is essentially based on complete Doppler sonographic evaluation of both lower limbs. In patients with no co-morbid condition, the D-dimer assay is useful to exclude the possibility of DVT. A positive diagnosis of DVT is based on the lack of venous compressibility and abnormal Doppler signal. The diagnostic accuracy relies on adequate knowledge of vascular anatomy and sufficient training, especially at the calf level. For experienced sonographers, the accuracy is similar at the thigh and calf level. In patients with suspected pulmonary embolus, evaluation of the lower extremity veins is mandatory and frequently performed with CT immediately following CT pulmonary angiography. However, this examination has not been validated yet.