| Objective: To evaluate the early changes of fat content and R2 * in abdominal organs after bariatric surgery with MRI IDEAL-IQ sequence,at the same time,a preliminary comparative analysis of the differences in the early changes of laparoscopic gastric sleeve resection(LSG)and laparoscopic gastric bypass surgery(LRYGB)was performed.Methods: A total of 84 patients who underwent bariatric surgery were prospectively collected from December 2018 to December 2019 in The Department of Bariatric Metabolism,Fourth Affiliated Hospital of China Medical University.3.0T MRI IDEAL-IQ scan was performed in the upper abdomen within 1 week before and 1 and 3 months after the operation.The fat fraction map and R2*map was automatically separated by the post-processing module of the equipment.In the post-processing workstation,select the circular measurement tool,place the ROI in the liver(each leaf,segment),pancreas(head,body,tail)and spleen of the fat fraction map to obtain the fat fraction(FF),R2 * value,and record the body mass index(BMI),weight and waist circumference of the patients before and after bariatric surgery.The preoperative and postoperative parameters were compared by paired sample t-test or Wilcoxon signed rank test.Independent sample t test was used to compare the two surgical methods.Pearson analysis was used for correlation analysis.The difference between the two methods was statistically significant(P < 0.05).Results: For all patients,18 patients completed 3 scans,and 45 completed only the first two scans.The body weight,BMI and waist circumference decreased significantly in the early stage after surgery.In the early stage after surgery,FF and R2 * of liver decreased continuously.36.84% of the patients with liver steatosis disappeared one month after surgery,and 86.67% patients had resolution of steatosis at three months after surgery.In the early stage after bariatric surgery,R2 * of pancreas decreased continuously,and the decrease was significant one month after bariatric surgery.There was no significant difference in the changes of FF and R2 * in the spleen at the early stage after bariatric surgery.The change of liver fat content in early stage after bariatric surgery was positively correlated with the change of liver iron content(r = 0.473,P = 0.001 at1 month after operation;r = 0.808,P <0.001 at 3 months after operation).The weight loss of LSG patients was more significant than that of LRYGB patients(LSG:-12.82 ± 2.74kg;LRYGB:-10.35 ± 2.48kg).The pancreatic head FF of LSG patients decreased at 1 month after bariatric surgery,while the pancreatic head FF increased in LRYGB patients.Conclusion: Bariatric surgery can effectively reduce the fat content and iron content of the liver in the early stage.The fat content of patients with fatty liver decreased significantly 3 months after bariatric surgery,with 86.67% of patients achieving resolution of steatosis.There was no significant difference between LSG and LRYGB in reducing liver fat and iron contentin early after bariatric surgery.The effect of LSG and LRYGB on the pancreatic fat content in the early postoperative period was reversed,and there was no significant difference in the effect on pancreatic iron content.FF and R2 * can be used as noninvasive,objective and quantitative biomarkers to evaluate the efficacy of bariatric surgery. |
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