Contrast Enhanced Ultrasound and Muscle

Inclusion Criteria: * Men and women over 40 years * Patients with chronic critical limb ischemia as defined by consensus TASC 2 and eligible to a revascularisation * Objective evaluation of critical ischemia is based on ankle pressure \< 70 mm Hg or toe pressure \< 50 mm Hg for patients with ulcer or pressure ankle pressure \< 50 mm Hg or toe pressure \< 30 mm Hg for patients with rest pain. * Patient's consent signed Exclusion Criteria: * Patients under 18 * Pregnant or breast feeding woman * Burger's disease * Contra- indication to use of contrast * Hypersensitivity to sulfurhexafluorure * Unstable coronary heart disease, acute stroke, uncompensated heart failure * Right to left shunt * Serious pulmonary hypertension (\> 90 mm Hg) * Uncontroled increased blood pressure * Acute respiratory distress syndrom * Consent refused * Patients with leg wounds preventing ultrasonography