MRI and MRE for non-invasive quantitative assessment of hepatic steatosis and fibrosis in NAFLD and NASH: Clinical trials to clinical practice  Parambir S. Dulai, Claude B. Sirlin, Rohit Loomba  Journal of Hepatology  Volume 65, Issue 5, Pages 1006-1016 (November 2016) DOI: 10.1016/j.jhep.2016.06.005 Copyright © 2016 European Association for the Study of the Liver Terms and Conditions

Fig. 1 Principles of MRI-PDFF assessment and quantification of hepatic steatosis. Moving left to right in the figure, you will first find the complex method of estimating PDFF, which acquires real and imaginary images to generate a PDFF map from 0–100%, labeled “C-MRI-PDFF” here. Next are the magnitude images which are squared to generate a PDFF map from 0–50%, labeled “M-MRI-PDFF” here. Both techniques acquire multiple images at echo times optimally spaced for fat water separation and T2∗ signal decay correction, and both apply a multi peak spectral model to correct for multi frequency interference effects of fat proton signals. Note that for magnitude-based PDFF, the calculated image only has a range of 0 to 50%. This is within the typical biological limits of liver fat content. Journal of Hepatology 2016 65, 1006-1016DOI: (10.1016/j.jhep.2016.06.005) Copyright © 2016 European Association for the Study of the Liver Terms and Conditions

Fig. 2 Co-localization of regions of interest and responsiveness of MRI-PDFF and MRE. Adapted and modified from Loomba et al. [119] (A) Anatomical co-localization of regions of interest. (B) Whole liver fat mapping with magnetic resonance imaging proton density fat fraction (MRI-PDFF) at weeks 0 and 24. (C) Whole liver fibrosis mapping with magnetic resonance elastography (MRE) at weeks 0 and 24. Journal of Hepatology 2016 65, 1006-1016DOI: (10.1016/j.jhep.2016.06.005) Copyright © 2016 European Association for the Study of the Liver Terms and Conditions