The investigators propose an exploratory study aiming at assessing the impact of surgical bariatric treatment on the improvement of pancreatic lesions detected by MRI.

Pancreatic MRI will be performed in severe-obese patients with a planned bariatric surgery, before and 6 months after bariatric surgery.

To assess the impact of bariatric surgery on pancreatic Magnetic Resonance Imaging (MRI) parameters in severe-obese patients

Inclusion Criteria:

• Adults (aged 18 to 65 years) with a planned for bariatric surgery (sleeve gastrectomy) according to HAS criteria
• Patients with severe obesity (BMI≥35)

Exclusion Criteria:

• Patients with problem of alcohol abuse (previous or current)
• Patients with problems of understanding
• Patients with previous acute or chronic pancreatitis
• Patients with contraindication to MRI (active implantable medical devices, pacemaker, claustrophobia …)
• Inability to undergo MRI due to weight excess
• Pregnant or breastfeeding woman
• Absence of free and informed consent
• Non affiliation to a social security regime or CMU (Universal health coverage)
• Patient under AME (State medical aid)
• Patient deprived of freedom, subject under a legal protective measure
• Patients who have already had bariatric surgery

Secondary exclusion criteria :

• Patients who have undergone bariatric surgery other than a sleeve gastrectomy