Effects of Morbid Obesity and Bariatric Surgery on Brain Inflammation, and Activation of Central Reward System

This is a prospective study, where subjects for the morbidly obese group (N=60) will be recruited from the patients undergoing bariatric surgery according to normal treatment protocol and the bariatric procedure is decided on clinical data together with the bariatric surgeon and the patient. The morbidly obese patients are studied before and 6 months after bariatric surgery. Results of obese are compared to results of healthy subjects (N=30), who are studied once. MRI studies: Brain structural MRI and MRS Structural brain MRI will be performed to obtain anatomical reference. The MR part of a 3T PET-MR system will be used for the study . MR spectroscopy (MRS) will be used to determine levels of different metabolites.Brain activation studies (functional MRI) The aim of the fMRI is to assess how morbid obesity and weight loss influence the brain reward system in response to visual cues (not food related); resting state fMRI will also be performed. Brain inflammation: \[¹¹C\]-PK11195 tracer with PET/CT is used to determine activation of glial cells, or inflammation, in the brain. After intravenous injection of 500 MBq \[¹¹C\]-PK11195, a 60-minute dynamic scan on the brain using the same PET/CT cameras will be performed. Both ROI- and SPM based statistics will be used in the statistical analyses. Whole-body scan with \[18F\]-FDG and PET/CT during euglycemic hyperinsulinemia used to promote tissue glucose uptake and measure insulin sensitivity. After 60 minutes from the start of clamp, the subjects will be injected intravenously with 150 MBq of \[18F\]-fluorodeoxyglucose (\[18F\]-FDG) Thereafter \[18F\]-fluorodeoxyglucose uptake in the brain, abdomen, femoral region will be measured.