Observed changes in brown, white, hepatic and pancreatic fat after bariatric surgery: Evaluation with MRI
To study the change in brown and white adipose tissue (BAT and WAT), as well as fat content in the liver and pancreas, in patients with morbid obesity before and after bariatric surgery.
Twelve patients with morbid obesity (F=8, M=4, age: 45.4 years (38.4–51.2), BMI: 35.2 kg/m2 (32.5–38.6)) underwent pre-op MRI at baseline and two post-op scans at 6-month and 12-month intervals after bariatric surgery. Co-registered water, fat, fat-fraction and T2* image series were acquired. Supraclavicular BAT and abdominal WAT were measured using in-house algorithms. Intrahepatic triglyceride (IHTG) was measured using MR spectroscopy and pancreatic fat was measured using a region-of-interest approach. Fat contents were compared between baseline and the first and second 6-month intervals using non-parametric analysis of Friedman’s test and Wilcoxon’s signed-rank test. Level of significance was selected at p=0.017 (0.05/3). Threshold of non-alcoholic fatty liver disease was set at 5.56%.
Results indicated that BMI (p=0.005), IHTG (p=0.005), and subcutaneous (p=0.005) and visceral adipose tissues (p=0.005) were significantly reduced 6 months after surgery. Pancreatic fat (p=0.009) was significantly reduced at 12 months. Most reduction became stable between the 6-month and 12-month interval. No significant difference was observed in BAT volume, fat-fraction and T2* values.
The results of this study suggest that bariatric surgery effectively reduced weight, mainly as a result of the reduction of abdominal WAT. Liver and pancreatic fat were deceased below the threshold possibly due to the reduction of free fatty acid. BAT volume, fat-fraction and T2* showed no significant changes, probably because surgery itself might not have altered the metabolic profile of the patients.
• No significant changes were observed in fat-fraction, T2* and volume of brown adipose tissue after bariatric surgery.
• Non-alcoholic fatty liver disease was resolved after surgery.
• Abdominal white fat and liver fat were significantly reduced 6 months after surgery and become stable between 6 and 12 months while pancreatic fat was significantly reduced between 0 and 12 months.
KeywordsMagnetic resonance imaging Magnetic resonance spectroscopy Brown adipose tissue White adipose tissue Bariatric surgery
Brown adipose tissue
Body mass index
Intraclass correlation coefficient
Laparoscopic greater curvature plication
Laparoscopic sleeve gastrectomy
Nonalcoholic fatty liver disease
Roux-en-Y gastric bypass
Subcutaneous adipose tissues
Uncoupling protein 1
Visceral adipose tissues
White adipose tissue
The authors would like to thank Candice Lam and Sabrina Ler for their kind support and assistance with subject recruitment.
This study has received funding by the Research Grant Council of Hong Kong. The work described in this paper was partially supported by grants from the Research Grants Council (Project No.: 14206716 and SEG_CUHK02) of the Hong Kong Special Administrative Region
Compliance with ethical standards
The scientific guarantor of this publication is Winnie CW Chu.
Conflict of interest
The authors of this paper declare no relationships with any companies whose products or services may be related to the subject matter of the article.
Statistics and biometry
No complex statistical methods were necessary for this paper.
Written informed consent was obtained from all subjects (patients) in this study.
Institutional Review Board approval was obtained.
• longitudinal study
• performed at one institution
- 1.McFarlane SI, Banerji M, Sowers JR (2001) Insulin resistance and cardiovascular disease. J Clin Endocrinol Metab 86:713–718Google Scholar
- 22.Chalasani N, Younossi Z, Lavine JE et al (2012) The diagnosis and management of non-alcoholic fatty liver disease: practice Guideline by the American Association for the Study of Liver Diseases, American College of Gastroenterology, and the American Gastroenterological Association. Hepatology 55:2005–2023CrossRefGoogle Scholar
- 23.European Association for the Study of the Liver (EASL), European Association for the Study of Diabetes (EASD) & European Association for the Study of Obesity (EASO) (2016) EASL-EASD-EASO Clinical Practice Guidelines for the management of non-alcoholic fatty liver disease. Diabetologia 59(6):1121–1140Google Scholar
- 26.Karamanakos SN, Vagenas K, Kalfarentzos F, Alexandrides TK (2008) Weight loss, appetite suppression, and changes in fasting and postprandial ghrelin and peptide-YY levels after Roux-en-Y gastric bypass and sleeve gastrectomy: a prospective, double blind study. Ann Surg 247:401–407CrossRefGoogle Scholar
- 36.Dadson P, Hannukainen JC, Din MU et al (2018) Brown adipose tissue lipid metabolism in morbid obesity: Effect of bariatric surgery-induced weight loss. Diabetes Obes Metab. https://doi.org/10.1111/dom.13233