Improved results for sleeve gastrectomy could be possible if more was known about the surgical / mechanical factors that affect outcome.

Effectiveness of sleeve gastrectomy is between gastric banding and gastric bypass. However, a proportion of patients that undergo surgery, report troublesome and persistent dysphagia, pain, new onset or worsening of gastro-esophageal reflux (GER) requiring treatment. Improved results for sleeve gastrectomy could be possible if more was known about the surgical / mechanical factors that affect outcome. Current investigations based on traditional intra-luminal imaging (endoscopy) and radiology (UGI series) may not provide adequate preoperative assessment of esophago-gastric dynamics. Current practice in the creation of a sleeve gastrectomy involves the use of a bougie or endoscope around which the sleeve is stapled. There is no consensus on the diameter of this bougie and this intraoperative calibration may alter the gastro-esophageal junction (GEJ) anatomy, does not provide real time physiology feedback, and allows only for a rough approximation of the size of the sleeve providing no information about the distensibility and pressure gradient of the newly created gastric tube as it is filled. A more distensible sleeve will have lower intra-gastric pressure, and thus will theoretically be expected to reduce the incidence of side effects. As laparoscopic sleeve gastrectomy is performed with increasing frequency, there is a need for development of tools to assist the surgeon in modeling properly and standardize the gastroplasty. This study will be based on a strict assessment of the anatomical and functional characteristics of the "ideal "gastric sleeve, using existing imaging modalities (endoscopy - CT scan- MRI - HRM).

Inclusion Criteria:

• Patient, male or female over 18 years old
• Patient scheduled to undergo a sleeve gastrectomy for obesity
• Patient with surgical indication validated by the obesity multidisciplinary meeting (RCP)
• Patient able to understand the study and to provide written informed consent
• Patient registered with the French social security regime

Non-inclusion criteria:

• Patient unable to give written informed consent
• Patient presenting contra-indication to the conduct of an MRI (claustrophobia, implantable medical devices)
• Patient presenting risks of allergic reaction to MRI contrast agents (gadolinium)
• Patient presenting, in the investigator's judgment, a condition or disease preventing their participation to study procedures
• Patient pregnant or breast-feeding
• Patient within exclusion period from other clinical trial
• Patient having forfeited their freedom of an administrative or legal obligation
• Patient being under guardianship