Purpose: The purpose of the present study was to determine liver, pancreas, kidney, and vertebral fat deposition in NAFLD patients by proton density fat fraction (PDFF) using magnetic resonance imaging (MRI) and to evaluate the relationships among them.
Methods: A total of 41 biopsy-proven NAFLD patients underwent MRI-PDFF with IDEAL-IQ. MRI protocol included T1-independent volumetric multi-echo gradient-echo imaging with T2* correction and spectral fat modeling. The MR examinations were performed on a 1.5 HDx MRI system. MRI-PDFF measurements were obtained from liver, pancreas, renal cortex and sinus, and vertebral body. Liver biopsy specimens were retrieved from the archives and evaluated by one pathologist according to NASH CRN.
Results: The median age of the patients was 47 years. The median interval between liver biopsy and MRI examination was 16 days. Mean liver, pancreas, renal cortex, renal sinus, T12 and L1 vertebral body MRI-PDFFs were 18.7%, 5.7%, 1.7%, 51%, 43.2%, and 43.5%, respectively. No correlation between either liver MRI-PDFF or histological steatosis, and other organ MRI-PDFFs was observed. A good correlation between pancreas and vertebral body MRI-PDFFs, and pancreas and renal sinus MRI-PDFFs was observed. Diabetic patients had higher average pancreas MRI-PDFF compared to non-diabetics (12.2%, vs., 4.8%; P = 0.028).
Conclusions: Pancreas and vertebral body MRI-PDFF is well correlated in NAFLD patients and both of them are higher in diabetic patients which may explain increased bone fractures in diabetics. MRI-PDFF can be used to demonstrate fat fractions of different organs and tissues and to understand fat metabolism.