title: Is MR spectroscopy really the best MR-based method for the evaluation of fatty liver in diabetic patients in clinical practice?
abstract: OBJECTIVE
  To investigate if magnetic resonance spectroscopy (MRS) is the best Magnetic Resonance (MR)-based method when compared to gradient-echo magnetic resonance imaging (MRI) for the detection and quantification of liver steatosis in diabetic patients in the clinical practice using liver biopsy as the reference standard, and to assess the influence of steatohepatitis and fibrosis on liver fat quantification.
  
  
  METHODS
  Institutional approval and patient consent were obtained for this prospective study. Seventy-three patients with type 2 diabetes (60 women and 13 men; mean age, 54 ± 9 years) underwent MRI and MRS at 3.0 T. The liver fat fraction was calculated from triple- and multi-echo gradient-echo sequences, and MRS data. Liver specimens were obtained in all patients. The accuracy for liver fat detection was estimated by receiver operator characteristic (ROC) analysis, and the correlation between fat quantification by imaging and histolopathology was analyzed by Spearman's correlation coefficients.
  
  
  RESULTS
  The prevalence of hepatic steatosis was 92%. All gradient-echo MRI and MRS findings strongly correlated with biopsy findings (triple-echo, rho = 0.819; multi-echo, rho = 0.773; MRS, rho = 0.767). Areas under the ROC curves to detect mild, moderate, and severe steatosis were: triple-echo sequences, 0.961, 0.975, and 0.962; multi-echo sequences, 0.878, 0.979, and 0.961; and MRS, 0.981, 0.980, and 0.954. The thresholds for mild, moderate, and severe steatosis were: triple-echo sequences, 4.09, 9.34, and 12.34, multi-echo sequences, 7.53, 11.75, and 15.08, and MRS, 1.71, 11.69, and 14.91. Quantification was not significantly influenced by steatohepatitis or fibrosis.
  
  
  CONCLUSIONS
  Liver fat quantification by MR methods strongly correlates with histopathology. Due to the wide availability and easier post-processing, gradient-echo sequences may represent the best imaging method for the detection and quantification of liver fat fraction in diabetic patients in the clinical practice.
authors.affiliation: D'Or Institute for Research and Education, Rio de Janeiro, Brazil; Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Daniella Braz
authors.initials: DB
authors.lastname: Parente
authors.affiliation: D'Or Institute for Research and Education, Rio de Janeiro, Brazil; Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Rosana Souza
authors.initials: RS
authors.lastname: Rodrigues
authors.affiliation: D'Or Institute for Research and Education, Rio de Janeiro, Brazil; Institute of Physics of São Carlos, University of São Paulo, São Carlos, Brazil.
authors.forename: Fernando Fernandes
authors.initials: FF
authors.lastname: Paiva
authors.affiliation: D'Or Institute for Research and Education, Rio de Janeiro, Brazil.
authors.forename: Jaime Araújo
authors.initials: JA
authors.lastname: Oliveira Neto
authors.affiliation: University of the State of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Lilian
authors.initials: L
authors.lastname: Machado-Silva
authors.affiliation: Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Valeria
authors.initials: V
authors.lastname: Lanzoni
authors.affiliation: University of the State of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Carlos Frederico Ferreira
authors.initials: CF
authors.lastname: Campos
authors.affiliation: D'Or Institute for Research and Education, Rio de Janeiro, Brazil; Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Antonio Luis
authors.initials: AL
authors.lastname: Eiras-Araujo
authors.affiliation: D'Or Institute for Research and Education, Rio de Janeiro, Brazil.
authors.forename: Pedro Emmanuel Alvarenga Americano
authors.initials: PE
authors.lastname: do Brasil
authors.affiliation: Université Paris Diderot Sorbonne, Paris, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Garteiser
authors.affiliation: University of the State of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Marilia de Brito
authors.initials: MB
authors.lastname: Gomes
authors.affiliation: D'Or Institute for Research and Education, Rio de Janeiro, Brazil; Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; University of the State of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Renata
authors.initials: R
authors.lastname: de Mello Perez
mesh_terms: D001706:Biopsy; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D005234:Fatty Liver / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D006801:Humans; D008099:Liver / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D012720:Severity of Illness Index