PET imaging tracks whole-body metabolic changes after surgery

A novel PET imaging framework reveals that bariatric surgery impacts not only body weight, but also the metabolic function of multiple organs. These PET-derived insights into organ-level responses to surgery could support more precise treatment monitoring and personalized metabolic care, according to a study, ‘Evaluation of organic metabolic profiling alternation assessed by [18F]FDG PET/CT in obese patients before and after bariatric surgery’,  presented at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2026 Annual Meeting.

Representative whole-body PET/CT based organ and tissue segmentation before and 12 months after bariatric surgery in a 20-year-old woman. Coronal PET/CT images and automated segmentation maps show multi-organ structural remodeling, including reductions in subcutaneous adipose tissue, visceral adipose tissue, liver, pancreas, spleen, and skeletal muscle, with apparent enlargement of the colon at 12-month follow-up. (Credit: SNMMI)

"Currently, clinicians do not have a clear way to see how the body's metabolism changes after bariatric surgery," said Zeyang Wang, PhD candidate in the Division of Nuclear Medicine, Department of Biomedical Imaging and Image-Guided Therapy at Medical University of Vienna in Austria. "Having a comprehensive understanding of the changes that are happening across multiple organs would provide valuable data to clinicians as they provide follow-up care."

The retrospective study included 32 patients with obesity undergoing laparoscopic sleeve gastrectomy or one-anastomosis gastric bypass who underwent whole-body 18F-FDG PET/CT and comprehensive laboratory assessments both before surgery and one year after surgery.

18F-FDG uptake was measured in subcutaneous and visceral adipose tissue, liver, pancreas, spleen, adrenal glands, and skeletal muscle to determine metabolic changes. Results were compared between the pre- and post-surgery scans and with those of healthy controls, and associations among organ-level metabolic changes were evaluated.

Surgery was found to induce coordinated metabolic changes across multiple organs, including fat, liver, pancreas, muscle, cardiovascular structures, bone-related tissues, and immune-endocrine organs. Changes in organ metabolism and volume correlated with improvements in glycaemic, lipid, endocrine, and inflammatory markers.

Network analysis showed stronger connections between organs, indicating that metabolic processes across the body became more synchronized after surgery.

"For patients, these findings suggest that metabolic recovery after bariatric surgery is a whole-body process," said Wang. "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."