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-β 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-β 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. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1905-1913.