Magnetic resonance imaging: Proton density fat fraction for assessment of pancreatic fatty infiltration during progression of T2DM bama minipigs

Background Recent studies have highlighted the correlation between diabetes and pancreatic fat infiltration. However, pancreatic fat content (PFC) is rarely confirmed by pathological results, and a change of PFC during progression of type 2 diabetes (T2DM) is currently controversial. Purpose To evaluate the relationship of MRI-pancreatic proton density fat fraction to serologic changes and histology in an experimental model of diabetes. Study Type Prospective animal study. Animal Model Thirteen Bama pigs were randomly assigned to diabetes (n = 7) or control (n = 6) groups. Pigs in the diabetic group received high-fat/high-sugar feed, combined with three doses of streptozotocin injections. Field Strength/Sequence 3.0T, IDEAL-IQ sequence. Assessment Starting in the fifth month, biochemical changes were evaluated; all pigs underwent axial MRI with the IDEAL-IQ sequence to measured pancreatic fat fraction (PFF). PFC was measured by the Soxhlet extraction method. Pancreatic fat distribution and pancreas islet morphology were observed by histopathology. Statistical Tests A Mann-Whitney U-test, independent-samples t-test, Pearson correlation, Spearman correlation, single-measure intraclass correlation coefficient (ICC) were performed. Results During the development of T2DM, the PFF, weight, fasting blood glucose (FBG), triglyceride (TG), total cholesterol (TCHO), low-density lipoprotein (LDL), and HOMA-IR (insulin resistance) of the experimental group showed an upward trend; fasting insulin (INS), high-density lipoprotein (HDL), and HOMA-beta showed decreasing trends. At the end of the fifteenth month, FBG (mmol/L) was 18.06 +/- 6.03 and 5.06 +/- 1.41 (P < 0.001), PFF (%) was 36.52 +/- 4.07 and 27.75 +/- 3.73 (P = 0.002), INS (mU/L) was 21.59 +/- 2.93 and 29.32 +/- 3.27 (P = 0.001), HOMA-IR was 16.83 +/- 4.22 and 6.70 +/- 2.45 (P < 0.001), HOMA-beta was 1.50 +/- 0.24 and 2.77 +/- 0.45 (P < 0.001), between the experimental and control groups. There were strong and moderate positive correlations between PFF and PFC (r = 0.968, P < 0.001), and FBG (r = 0.657, P = 0.015), and HOMA-IR (r = 0.608, P = 0.028). Data Conclusion MRI-proton density fat fraction can measure the fat content of the pancreas with great accuracy and repeatability; PFF is a potential biomarker that can reflect the different stages of diabetes development. Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1905-1913.