European Radiology

, Volume 29, Issue 2, pp 849–856 | Cite as

Observed changes in brown, white, hepatic and pancreatic fat after bariatric surgery: Evaluation with MRI

  • Steve C. N. Hui
  • Simon K. H. Wong
  • Qiyong Ai
  • David K. W. Yeung
  • Enders K. W. Ng
  • Winnie C. W. ChuEmail author
Magnetic Resonance



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.

Key Points

• 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.


Magnetic resonance imaging Magnetic resonance spectroscopy Brown adipose tissue White adipose tissue Bariatric surgery 



Brown adipose tissue


Body mass index


Intraclass correlation coefficient


Intrahepatic triglyceride


Interquartile range


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.

Informed consent

Written informed consent was obtained from all subjects (patients) in this study.

Ethical approval

Institutional Review Board approval was obtained.


• prospective

• longitudinal study

• performed at one institution


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Copyright information

© European Society of Radiology 2018

Authors and Affiliations

  1. 1.Department of Imaging and Interventional RadiologyPrince of Wales Hospital, The Chinese University of Hong KongSha TinHong Kong SAR
  2. 2.Department of SurgeryPrince of Wales Hospital, The Chinese University of Hong KongSha TinHong Kong SAR
  3. 3.Department of Clinical OncologyPrince of Wales Hospital, The Chinese University of Hong KongSha TinHong Kong SAR

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