This study evaluates changes in pancreatic fat and recovery of pancreatic function in obese patients undergoing laparoscopic sleeve gastrectomy (LSG), a weight-loss surgery. Obesity can cause fat to accumulate in the pancreas, which may impair insulin production and lead to type 2 diabetes. This study uses magnetic resonance imaging (MRI) to measure pancreatic fat before and after surgery to understand how weight loss affects pancreatic function. About 50 obese patients (BMI \> 32 kg/m²) aged 16-60 years who are scheduled for LSG will be enrolled. Participants will undergo MRI scans of the pancreas and blood tests before surgery and at 1, 3, and 6 months after surgery. The MRI uses a safe, non-invasive technique called Dixon imaging to measure fat content in different parts of the pancreas (head, body, and tail). Blood tests will measure fasting glucose, insulin, C-peptide, and HbA1c to assess pancreatic function. The study aims to determine whether reduction in pancreatic fat after weight-loss surgery is associated with improved insulin secretion and reduced insulin resistance. This information may help doctors better understand how bariatric surgery improves metabolic health and guide postoperative patient management. Participation involves no additional risk beyond routine clinical care. All MRI scans and blood tests are part of standard postoperative monitoring for bariatric surgery patients.
See attached protocol for detailed study design, eligibility criteria, and outcome measures.
Study Type
OBSERVATIONAL
Enrollment
50
Standard laparoscopic sleeve gastrectomy performed by experienced surgeons. This is the routine clinical procedure for weight loss, not an experimental intervention. The study observes pancreatic fat changes and metabolic outcomes following this standard surgery.
Qingdao University Affiliated Hospital
Qingdao, Shandong, China
Change in Pancreatic Fat Content
Pancreatic fat fraction will be measured using MRI Dixon imaging at pancreatic head, body, and tail. Fat fraction (%) = \[(SI in-phase - SI opposed-phase) / (2 × SI in-phase)\] × 100.
Time frame: Baseline (preoperative), 1 month, 3 months, and 6 months postoperatively
Change in Insulin Resistance Index (HOMA-IR)
Insulin resistance will be assessed using the Homeostasis Model Assessment for Insulin Resistance (HOMA-IR) calculated as: \[fasting plasma glucose (mmol/L) × fasting insulin (μU/mL)\] / 22.5. Fasting plasma glucose will be measured by glucose oxidase method and fasting insulin will be measured by chemiluminescence immunoassay. Higher HOMA-IR values indicate greater insulin resistance.
Time frame: Baseline (preoperative), 1 month, 3 months, and 6 months postoperatively
Change in Pancreatic Beta-cell Function
Pancreatic beta-cell function will be assessed using HOMA-%β (Homeostasis Model Assessment for beta-cell function) calculated as: HOMA-%β = \[20 × fasting insulin (μU/mL)\] / \[fasting glucose (mmol/L) - 3.5\] (%). Fasting blood glucose, fasting insulin, C-peptide, and HbA1c will be measured at each time point.
Time frame: Baseline (preoperative), 1 month, 3 months, and 6 months postoperatively
Change in Body Weight and BMI
Body weight will be measured using calibrated electronic scales with subjects wearing light clothing and no shoes. Height will be measured using a stadiometer. BMI will be calculated as weight (kg) divided by height squared (m²). Percentage of total weight loss (%TWL) and percentage of excess weight loss (%EWL) will also be calculated to assess surgical efficacy.
Time frame: Baseline (preoperative), 1 month, 3 months, and 6 months postoperatively
Change in Pancreatic Fat Distribution (Head, Body, Tail)
Regional pancreatic fat content will be measured separately at pancreatic head, body, and tail using MRI Dixon imaging. Three regions of interest (ROI) will be drawn at the maximal cross-sectional area of each pancreatic segment. Fat fraction (%) = \[(SI in-phase - SI opposed-phase) / (2 × SI in-phase)\] × 100. This allows assessment of differential fat reduction patterns across pancreatic regions and correlation with regional islet function recovery.
Time frame: Baseline (preoperative), 1 month, 3 months, and 6 months postoperatively
Correlation Between Pancreatic Fat Reduction and Islet Function Recovery
Correlation analysis between the magnitude of pancreatic fat reduction (measured by MRI Dixon) and improvement in islet function parameters (HOMA-%β, HOMA-IR, fasting insulin, C-peptide). This will identify whether pancreatic fat reduction is an independent predictor of beta-cell function recovery after laparoscopic sleeve gastrectomy.
Time frame: Baseline to 6 months postoperatively (change scores will be calculated)
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