title: Correlation between liver histology and novel magnetic resonance imaging in adult patients with non-alcoholic fatty liver disease - MRI accurately quantifies hepatic steatosis in NAFLD.
abstract: BACKGROUND
  Conventional magnetic resonance imaging (MRI) techniques that measure hepatic steatosis are limited by T1 bias, T(2)* decay and multi-frequency signal-interference effects of protons in fat. Newer MR techniques such as the proton density-fat fraction (PDFF) that correct for these factors have not been specifically compared to liver biopsy in adult patients with non-alcoholic fatty liver disease (NAFLD).
  
  
  OBJECTIVE
  To examine the association between MRI-determined PDFF and histology-determined steatosis grade, and their association with fibrosis.
  
  
  METHODS
  A total of 51 adult patients with biopsy-confirmed NAFLD underwent metabolic-biochemical profiling, MRI-determined PDFF measurement of hepatic steatosis and liver biopsy assessment according to NASH-CRN histological scoring system.
  
  
  RESULTS
  The average MRI-determined PDFF increased significantly with increasing histology-determined steatosis grade: 8.9% at grade-1, 16.3% at grade-2, and 25.0% at grade-3 with P ≤ 0.0001 (correlation: r(2) = 0.56, P < 0.0001). Patients with stage-4 fibrosis, when compared with patients with stage 0-3 fibrosis, had significantly lower hepatic steatosis by both MRI-determined PDFF (7.6% vs. 17.8%, P < 0.005) and histology-determined steatosis grade (1.4 vs. 2.2, P < 0.05). NAFLD patients with grade 1 steatosis were more likely to have characteristics of advanced liver disease including higher average AST:ALT (0.87 vs. 0.60, P < 0.02), GGT (140 vs. 67, P < 0.01), and INR (1.06 vs. 0.99, P < 0.01), higher stage of fibrosis and hepatocellular ballooning.
  
  
  CONCLUSIONS
  MRI-determined proton density-fat fraction correlates with histology-determined steatosis grade in adults with NAFLD. Steatosis is non-linearly related to fibrosis progression. In patients with NAFLD, a low amount of hepatic steatosis on imaging does not necessarily indicate mild disease.
authors.affiliation: Division of Internal Medicine, Department of Medicine, University of California, San Diego, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Permutt
authors.forename: T-A
authors.initials: TA
authors.lastname: Le
authors.forename: M R
authors.initials: MR
authors.lastname: Peterson
authors.forename: E
authors.initials: E
authors.lastname: Seki
authors.forename: D A
authors.initials: DA
authors.lastname: Brenner
authors.forename: C
authors.initials: C
authors.lastname: Sirlin
authors.forename: R
authors.initials: R
authors.lastname: Loomba
mesh_terms: D000328:Adult; D001706:Biopsy; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005234:Fatty Liver / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008099:Liver / Q000473:pathology*; D008103:Liver Cirrhosis / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D065626:Non-alcoholic Fatty Liver Disease; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012720:Severity of Illness Index