Non Invasive Measurements of Fibrosis, Inflammation and Steatohepatitis in Morbidly Obese Patients

Main objective : The main objective of the study was to determine in patients with morbid obesity waiting for bariatric surgery, the accuracy of non-invasive tests for diagnosis of severe steatosis and / or NASH. The gold standard is liver biopsy with a morphometric study. Non-invasive tests will be used: * Serum tests: the FibroMax (which includes the NASH test, FibroTest and SteatoTest) and FibroMeter. * Radiological examinations: MRI and FibroScan / CAP Secondary objectives : The secondary objectives are: 1. to determine the accuracy of these non-invasive tests for the diagnosis of severe steatosis alone, steatohepatitis (NASH or) and hepatic fibrosis 2. to determine the best combination of these tests to better evaluate the presence of severe steatosis, NASH and a hepatic fibrosis. 3. to quantify MRI visceral and subcutaneous fat in morbidly obese patients Research Design : 1. Judging Criteria Primary endpoint To validate the use of serum tests, FibroScan / CAP abdominal MRI for the diagnosis of severe steatosis and / or NASH (specificity, sensitivity, positive and negative predictive values). The gold standard is the result of histology on liver biopsy, with a morphometric study. For each diagnostic test, a ROC curve is used to determine the best compromise between sensitivity and specificity. The histological diagnosis of severe steatosis is defined by the presence of hepatic steatosis grade 3 or higher. The diagnosis of NASH is defined by the presence of lobular inflammation with neutrophils and hepatocytes ballooning. Secondary endpoints \- Histological lesions of liver fibrosis Quantification of abdominal fat by MRI (in the form of three variables of interest: quantification of the surface of the visceral fat from the surface of the subcutaneous fat and the amount of intrahepatic fat assessed by the percentage loss of signal). 2. Methodology and expected number of patients in research This is a prospective study evaluating the value of noninvasive tests for the diagnosis of hepatic lesions in morbid obese patients. The MRI system "open" allows access to obese patients. Three such systems are available in France and liver pathology is supported only on the system of Louis Mourier. The reference method is liver histology; tests studied are MRI abdominal Fibroscan / CAP, and serum tests (FibroTest, FibroMeter, SteatoTest, NASH test). The study will be conducted in 200 obese patients who will have a liver biopsy performed during bariatric surgery: * Tests for the detection of steatosis (fat quantification of intrahepatic MRI measurement of steatosis by CAP, serum tests) and evaluating histological steatosis (main objective) * Tests for the detection of NASH (test serum) and histology * Tests of fibrosis (serum tests; FibroScan) and histological data assessing fibrosis. The duration and extent of obesity (BMI) and biological data (HOMA-test) will be taken into account. 3. Examinations required specifically for research Liver biopsy is routinely performed intraoperatively in the routine monitoring of patients for bariatric surgery, examinations specific to the research are: * Serum tests * FibroScan / CAP * Abdominal MRI Risk / risk absences The sting at blood sampling can cause the formation of a small hematoma without gravity, which will subside spontaneously within a few days. FibroScan ® / CAP presents no risk of side effects. Liver MRI shows no risk if the cons-indications are respected. Wearing a stack (pacemaker) or any element that contains the iron near the eyes or head are contra-indications as are a major risk factor (risk of death, blindness). The presence of a heart valve or a stent (also called metal prosthesis) is not an absolute contra-indication-and their compatibility with MRI will be verified before completion of the examination, as is the case in practice clinic .. Liver biopsy, which is part of the examinations carried out in a systematic way without any protocol adds no additional risk to the surgical 4. Study site The study will be conducted at Louis Mourier, a reference center for the treatment of obesity, which has an open system allowing access to obese. 5. Indications for bariatric surgery Indications for bariatric surgery at Louis Mourier, a reference center for the treatment of obesity, are consistent with the recommendations of the HAS in 2009, based on professional consensus. Surgery is indicated in patients with all of the following criteria: 1. BMI ≥ 40 or BMI ≥ 35 with comorbid 2. failure (s) prior (s) of the conventional treatment of obesity combined dietary, physical activity and behavioral therapy 3. appraisal nutritionally: global, personal and non-surgical 4. considered only after medical treatment for a minimum of 1 year 5. well-informed and motivated patients, with acceptable surgical risks 6. obesity stable (or worsening) for five years 7. absence of endocrine pathology (adrenal, thyroid) may be due to obesity