Fatty liver in the obese is a common finding; some cases develop steato-hepatosis which in the long-term can lead to liver cirrhosis. The effect of bariatric surgery on fat distribution in the liver has so far been studied with liver biopsies and single voxel MR techniques. With this trial investigators present a new, whole organ MR-quantification of liver fat and describe changes after bariatric surgery in visceral and subcutaneous fat.

Currently, liver biopsy is still regarded as the gold-standard in the diagnosis of non-alcoholic fatty liver disease and monitoring of progression. However, accuracy of diagnosis is not perfect with a certain risk of sampling error depending on biopsy quality and a more or less homogeneous distribution of liver tissue alterations. Complications are rare; however, the method is invasive and carries the risk of bleeding. Therefore, non-invasive methods (such as serum biomarkers or imaging techniques) are sought for accurate diagnosis and safe monitoring of disease progression. Unidimensional transient elastography (TE; FibroScan®) is a non-invasive technique, which can be a helpful tool here: however, accuracy of diagnosis is depending on the stage of fibrosis and lower grades of fibrosis (stage 1 and 2) are difficult to assess. Moreover, in obese patients this method cannot be applied.

In recent years, the development of fat-water magnetic resonance imaging has enabled non-invasive assessment of fat and water content in tissues. In addition, modern MRI devices allow brief breath holding, which reduces motion artifacts and provides us with excellent data and therefore MRI has become an important tool for fat quantification.

Up to date only a few studies have focused on fat quantification before and after bariatric surgery: patients treated with laparoscopic gastric banding (a purely restrictive procedure) and patients undergoing metabolic surgery such as sleeve gastrectomy and gastric bypass have been examined pre- and postoperatively by means of MRI fat quantification. However, in these studies single voxel spectroscopy was used. In contrast, in this current trial investigators aim to assess full organ volume, which hopefully will provide more accurate data.

Inclusion Criteria:

• morbidly obese patients with BMI over 35, scheduled for bariatric surgery (either sleeve gastrectomy or gastric bypass)

Exclusion Criteria:

• Smoking
• substance abuse
• Diabetes
• history of gastrointestinal disorders
• pace-maker
• claustrophobia