title: Nonalcoholic fatty liver disease: MR imaging of liver proton density fat fraction to assess hepatic steatosis.
abstract: OBJECTIVE
  To evaluate the diagnostic performance of magnetic resonance (MR) imaging-estimated proton density fat fraction (PDFF) for assessing hepatic steatosis in nonalcoholic fatty liver disease (NAFLD) by using centrally scored histopathologic validation as the reference standard.
  
  
  METHODS
  This prospectively designed, cross-sectional, internal review board-approved, HIPAA-compliant study was conducted in 77 patients who had NAFLD and liver biopsy. MR imaging-PDFF was estimated from magnitude-based low flip angle multiecho gradient-recalled echo images after T2* correction and multifrequency fat modeling. Histopathologic scoring was obtained by consensus of the Nonalcoholic Steatohepatitis (NASH) Clinical Research Network Pathology Committee. Spearman correlation, additivity and variance stabilization for regression for exploring the effect of a number of potential confounders, and receiver operating characteristic analyses were performed.
  
  
  RESULTS
  Liver MR imaging-PDFF was systematically higher, with higher histologic steatosis grade (P < .001), and was significantly correlated with histologic steatosis grade (ρ = 0.69, P < .001). The correlation was not confounded by age, sex, lobular inflammation, hepatocellular ballooning, NASH diagnosis, fibrosis, or magnetic field strength (P = .65). Area under the receiver operating characteristic curves was 0.989 (95% confidence interval: 0.968, 1.000) for distinguishing patients with steatosis grade 0 (n = 5) from those with grade 1 or higher (n = 72), 0.825 (95% confidence interval: 0.734, 0.915) to distinguish those with grade 1 or lower (n = 31) from those with grade 2 or higher (n = 46), and 0.893 (95% confidence interval: 0.809, 0.977) to distinguish those with grade 2 or lower (n = 58) from those with grade 3 (n = 19).
  
  
  CONCLUSIONS
  MR imaging-PDFF showed promise for assessment of hepatic steatosis grade in patients with NAFLD. For validation, further studies with larger sample sizes are needed.
authors: Liver Imaging Group, Department of Radiology, University of California San Diego, 408 Dickinson St, San Diego, CA 92103-8226, USA.
authors: An
authors: A
authors: Tang
authors: Justin
authors: J
authors: Tan
authors: Mark
authors: M
authors: Sun
authors: Gavin
authors: G
authors: Hamilton
authors: Mark
authors: M
authors: Bydder
authors: Tanya
authors: T
authors: Wolfson
authors: Anthony C
authors: AC
authors: Gamst
authors: Michael
authors: M
authors: Middleton
authors: Elizabeth M
authors: EM
authors: Brunt
authors: Rohit
authors: R
authors: Loomba
authors: Joel E
authors: JE
authors: Lavine
authors: Jeffrey B
authors: JB
authors: Schwimmer
authors: Claude B
authors: CB
authors: Sirlin
mesh_terms: D000293:Adolescent; D000328:Adult; D001706:Biopsy; D002648:Child; D003430:Cross-Sectional Studies; D005234:Fatty Liver / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D065626:Non-alcoholic Fatty Liver Disease; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011522:Protons; D012372:ROC Curve; D012680:Sensitivity and Specificity
chemical_list: D011522:Protons
references: N Engl J Med. 2001 Feb 15;344(7):495-500
references: 11172192
references: J Hepatol. 2009 Aug;51(2):389-97
references: 19505740
references: Scand J Gastroenterol. 2011 Jun;46(6):727-31
references: 21366386
references: Aliment Pharmacol Ther. 2012 Jul;36(1):22-9
references: 22554256
references: AJR Am J Roentgenol. 2010 Apr;194(4):964-71
references: 20308498
references: Radiology. 2009 Oct;253(1):90-7
references: 19587308
references: J Magn Reson Imaging. 2010 Jul;32(1):148-54
references: 20578022
references: Magn Reson Imaging. 2008 Apr;26(3):347-59
references: 18093781
references: Gastroenterology. 2005 Jun;128(7):1898-906
references: 15940625
references: Ann Surg. 2009 Nov;250(5):691-7
references: 19806055
references: Contemp Clin Trials. 2009 Jan;30(1):88-96
references: 18804555
references: Am J Physiol Endocrinol Metab. 2005 Feb;288(2):E462-8
references: 15339742
references: Radiology. 2010 Jan;254(1):119-28
references: 20032146
references: Radiology. 2009 Jan;250(1):95-102
references: 19092092
references: Radiology. 2005 Nov;237(2):507-11
references: 16244259
references: Radiology. 2005 Dec;237(3):1048-55
references: 16237138
references: Hepatology. 2005 Jun;41(6):1313-21
references: 15915461
references: J Magn Reson Imaging. 2011 Apr;33(4):873-81
references: 21448952
references: J Gastroenterol Hepatol. 2002 Feb;17 Suppl:S186-90
references: 12000605
references: J Magn Reson Imaging. 2011 Jan;33(1):119-27
references: 21182129
references: J Hepatol. 2010 Apr;52(4):579-85
references: 20185194
references: J Magn Reson Imaging. 2007 Oct;26(4):1153-61
references: 17896369
references: Am J Gastroenterol. 2002 Oct;97(10):2614-8
references: 12385448
references: Magn Reson Med. 2007 Aug;58(2):354-64
references: 17654578
references: J Magn Reson Imaging. 2011 Oct;34(4):729-749
references: 22025886
references: J Magn Reson Imaging. 1995 May-Jun;5(3):281-5
references: 7633104
references: Dig Dis. 2010;28(1):155-61
references: 20460905
references: J Hepatol. 2005 Jan;42(1):132-8
references: 15629518
references: Semin Liver Dis. 2008 Nov;28(4):370-9
references: 18956293
references: J Magn Reson Imaging. 2009 Jun;29(6):1332-9
references: 19472390
references: J Magn Reson Imaging. 2011 Oct;34(4):928-34
references: 21769986
references: Radiology. 2008 May;247(2):550-7
references: 18349314
references: Contemp Clin Trials. 2010 Jan;31(1):62-70
references: 19761871
references: Pediatrics. 2006 Oct;118(4):1388-93
references: 17015527
references: Am J Gastroenterol. 1999 Sep;94(9):2467-74
references: 10484010
references: Hepatology. 2003 Dec;38(6):1449-57
references: 14647056
references: Magn Reson Imaging. 2010 Jul;28(6):767-76
references: 20409663
references: AJR Am J Roentgenol. 2012 Mar;198(3):582-8
references: 22357996
references: Radiology. 2011 Jun;259(3):749-56
references: 21460032
references: Radiology. 2011 Mar;258(3):767-75
references: 21248233
references: Clin Res Hepatol Gastroenterol. 2011 Jan;35(1):23-8
references: 21634051
references: Liver Int. 2008 May;28(5):650-8
references: 18331241
references: Magn Reson Imaging. 2012 Feb;30(2):151-7
references: 22055856
references: Radiology. 2011 Mar;258(3):749-59
references: 21212366
references: NMR Biomed. 2011 Aug;24(7):784-90
references: 21834002
references: Radiology. 2009 Apr;251(1):67-76
references: 19221054