Deep vein thrombosis (DVT) is a vascular disease characterized by the formation of a thrombus within the venous system, mainly the lower limbs. The clot structure directly influences both its location, but also its progressive profile expansion material or regression and embolic migration.

Few data are available regarding the evolution of structural properties of thrombus after an acute episode of DVT. Thrombus formation is due to the polymerization of fibrinogen into fibrin. Fibrin is a viscoelastic polymer. Its mechanical properties directly determine how the thrombus responds to forces which it is subjected.

Determining the mechanical properties of the thrombus in vivo and ex vivo is expected to study its evolutionary properties.

The main objective of the study is to characterize the in vivo properties of elastographic thrombus in patients with proximal deep vein thrombosis (DVT), for quantitative elastography performed at D0, D7, D30.

The ability to analyze the structural properties of the thrombus should allow us to then correlate these properties to the evolving nature of the thrombus (embolic migration or not, recanalization or not), and the effect of different treatment on the evolution of the thrombus

Inclusion Criteria:

• Patient with proximal DVT, provoked or not, the symptomatology is less than 3d, with or without pulmonary embolism treated with heparin or oral anticoagulant
• Signed informed consent
• Patient affiliated to a social security scheme,

Exclusion Criteria:

• pregnant or lactating
• Life expectancy <1 month
• Patient with distal DVT or asymptomatic DVT accidental discovery
• Patient who underwent venous unclogging in acute phase
• exclusion period in another study,
• under administrative or judicial oversight, under guardianship