Whole-Body PET/CT Tracks Metabolic Changes After Bariatric Surgery

Obesity surgery improves weight and comorbidity profiles, yet clinicians lack tools to monitor organ-level metabolic recovery after the procedure. A clear view of systemic changes could refine follow-up care and reduce postoperative risks. Nuclear medicine can quantify tissue metabolism across the body in a single session. Researchers have now developed a positron emission tomography/computed tomography (PET/CT) framework to track whole-body metabolic changes after bariatric surgery.

Developed at the Medical University of Vienna, the approach uses whole-body PET/CT with fluorodeoxyglucose (18F-FDG) to profile tissue glucose metabolism across multiple organs. Automated organ and tissue segmentation enables quantitative assessment of postoperative remodeling. The findings were presented at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2026 Annual Meeting.

In a retrospective study, 32 adults with obesity underwent either laparoscopic sleeve gastrectomy or one-anastomosis gastric bypass. Each patient received whole-body 18F-FDG PET/CT and comprehensive laboratory assessments before surgery and at 12 months. Metabolic activity was measured in subcutaneous and visceral adipose tissue, liver, pancreas, spleen, adrenal glands, and skeletal muscle. Pre- and post-surgery scans were compared with those of healthy controls, and associations among organ-level changes were analyzed.

Surgery induced coordinated metabolic changes across fat, liver, pancreas, muscle, cardiovascular structures, bone-related tissues, and immune–endocrine organs. Alterations in organ metabolism and volume correlated with improvements in glycemic, lipid, endocrine, and inflammatory markers. Network analysis indicated stronger inter-organ connections, suggesting more synchronized systemic metabolism after surgery. These PET-derived insights may support more precise treatment monitoring and personalized metabolic care.

“For patients, these findings suggest that metabolic recovery after bariatric surgery is a whole-body process. Molecular imaging may help show how different organs respond after surgery, beyond what can be measured by weight loss or blood tests alone. This work supports the use of whole-body PET/CT as a tool to map organ-level metabolic health,” said Zeyang Wang, MSc, Ph.D. candidate in the Division of Nuclear Medicine, Department of Biomedical Imaging and Image-Guided Therapy at Medical University of Vienna in Austria.

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