title: Focal Nodular Hyperplasia and Hepatocellular Adenoma: Accuracy of Gadoxetic Acid-enhanced MR Imaging--A Systematic Review.
abstract: OBJECTIVE
  To perform a systematic review to evaluate the diagnostic accuracy of hepatobiliary (HPB) phase gadoxetic acid-enhanced MR imaging of the liver in the diagnosis of focal nodular hyperplasia (FNH) versus hepatocellular adenoma (HCA) and to identify the rate of (a) reported HCAs that are iso- or hyperintense to liver and (b) reported FNHs that are hypointense to liver on HPB phase MR images.
  
  
  METHODS
  The institutional review board granted a waiver for this study type, and multiple databases were searched for studies in which researchers distinguished between FNH and HCA with gadoxetic acid-enhanced MR imaging. Studies to evaluate diagnostic accuracy were included; case reports and series were included to analyze the rate of iso- or hyperintense HCAs on HPB phase MR images. Risk of bias was assessed by using the Quality Assessment Tool for Diagnostic Accuracy Studies-2. Sensitivity and specificity were plotted with a forest plot; pooling was not performed because a small number of heterogeneous studies were included. Rate of iso- or hyperintense HCA on HPB phase gadoxetic acid-enhanced MR images was evaluated.
  
  
  RESULTS
  Six studies (309 patients; 164 with HCA, 233 with FNH) were included for diagnostic accuracy assessment. Twelve case series (129 patients; 81 with HCA, 70 with FNH) were included (studies with insufficient 2 × 2 table data for diagnostic accuracy assessment). Sensitivity was high (range, 0.91-1.00; lower margin of the 95% confidence interval: 0.77). Specificity was high (range, 0.87-1.00; lower margin of the 95% confidence interval: 0.54). Specificity was lowest among studies in which molecular subtyping of HCA was performed. Rate of iso-or hyperintensity of HCA on HPB phase MR images was variable (range, 0%-67%) and occurred more frequently in the inflammatory subtype. High risk of bias was identified in the domains of patient selection and reference standard.
  
  
  CONCLUSIONS
  The reported diagnostic accuracy of HPB phase gadoxetic acid-enhanced MR imaging in the diagnosis of HCA versus FNH is high; however, studies are few, heterogeneous, and at high risk for bias, indicating that diagnostic accuracy may be overestimated.
authors.affiliation: From the Department of Radiology, Clinical Epidemiology Program, University of Ottawa, Ottawa Hospital Research Institute, 1053 Carling Ave, Ottawa Hospital Civic Campus, Room c159, Ottawa ON, Canada K1Y 4E9.
authors.forename: Matthew D F
authors.initials: MD
authors.lastname: McInnes
authors.affiliation: From the Department of Radiology, Clinical Epidemiology Program, University of Ottawa, Ottawa Hospital Research Institute, 1053 Carling Ave, Ottawa Hospital Civic Campus, Room c159, Ottawa ON, Canada K1Y 4E9.
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Hibbert
authors.affiliation: From the Department of Radiology, Clinical Epidemiology Program, University of Ottawa, Ottawa Hospital Research Institute, 1053 Carling Ave, Ottawa Hospital Civic Campus, Room c159, Ottawa ON, Canada K1Y 4E9.
authors.forename: João R
authors.initials: JR
authors.lastname: Inácio
authors.affiliation: From the Department of Radiology, Clinical Epidemiology Program, University of Ottawa, Ottawa Hospital Research Institute, 1053 Carling Ave, Ottawa Hospital Civic Campus, Room c159, Ottawa ON, Canada K1Y 4E9.
authors.forename: Nicola
authors.initials: N
authors.lastname: Schieda
mesh_terms: D018248:Adenoma, Liver Cell / Q000175:diagnosis*; D003287:Contrast Media; D020518:Focal Nodular Hyperplasia / Q000175:diagnosis*; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008113:Liver Neoplasms / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA