Quantification of intrapancreatic fat in type 2 diabetes by MRI

• Published in: PloS one Vol. 12; no. 4; p. e0174660
• Main Authors: Al-Mrabeh, Ahmad, Hollingsworth, Kieren G, Steven, Sarah, Tiniakos, Dina, Taylor, Roy
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 03-04-2017; Public Library of Science (PLoS)
• Subjects: Adipocytes; Adolescent; Adult; Aged; Autoimmune diseases; Biology and Life Sciences; Blood glucose; Care and treatment; Coefficient of variation; Datasets; Diabetes; Diabetes mellitus; Diabetes Mellitus, Type 2 - physiopathology; Female; Gastroenterology; Health aspects; Humans; Image analysis; Image Processing, Computer-Assisted; Immunology; Insulin resistance; Intra-Abdominal Fat - diagnostic imaging; Intra-Abdominal Fat - physiology; Lipids; Liver diseases; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Male; Medicine; Medicine and Health Sciences; Metabolism; Middle Aged; NMR; Nuclear magnetic resonance; Obesity; Observer Variation; Oxidative stress; Pancreas; Pancreas - diagnostic imaging; Pancreas - physiology; Parenchymal Tissue - diagnostic imaging; Parenchymal Tissue - physiology; Reproducibility of Results; Research and Analysis Methods; Rodents; Studies; Tissues; Type 2 diabetes; Weight control; Young Adult
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0174660

Accumulation of intrapancreatic fat may be important in type 2 diabetes, but widely varying data have been reported. The standard quantification by MRI in vivo is time consuming and dependent upon a high level of experience. We aimed to develop a new method which would minimise inter-observer variation and to compare this against previously published datasets.
A technique of 'biopsying' the image to minimise inclusion of non-parenchymal tissues was developed. Additionally, thresholding was applied to exclude both pancreatic ducts and intrusions of visceral fat, with pixels of fat values of <1% or >20% being excluded. The new MR image 'biopsy' (MR-opsy) was compared to the standard method by 6 independent observers with wide experience of image analysis but no experience of pancreas imaging. The effect of the new method was examined on datasets from two studies of weight loss in type 2 diabetes.
At low levels of intrapancreatic fat neither the result nor the inter-observer CV was changed by MR-opsy, thresholding or a combination of the methods. However, at higher levels the conventional method exhibited poor inter-observer agreement (coefficient of variation 26.9%) and the new combined method improved the CV to 4.3% (p<0.03). Using either MR-opsy alone or with thresholding, the new methods indicated a closer relationship between decrease in intrapancreatic fat and fall in blood glucose.
The inter-observer variation for quantifying intrapancreatic fat was substantially improved by the new method when pancreas fat levels were moderately high. The method will improve comparability of pancreas fat measurement between research groups.