title: Retrospective comparison of gradient recalled echo R2* and spin-echo R2 magnetic resonance analysis methods for estimating liver iron content in children and adolescents.
abstract: BACKGROUND
  Serial surveillance of liver iron concentration (LIC) provides guidance for chelation therapy in patients with iron overload. The diagnosis of iron overload traditionally relies on core liver biopsy, which is limited by invasiveness, sampling error, cost and general poor acceptance by pediatric patients and parents. Thus noninvasive diagnostic methods such as MRI are highly attractive for quantification of liver iron concentration.
  
  
  OBJECTIVE
  To compare two MRI-based methods for liver iron quantification in children.
  
  
  METHODS
  64 studies on 48 children and young adults (age range 4-21 years) were examined by gradient recalled echo (GRE) R2* and spin-echo R2 MRI at 1.5T to evaluate liver iron concentration. Scatter plots and Bland-Altman difference plots were generated to display and assess the relationship between the methods.
  
  
  RESULTS
  With the protocols used in this investigation, Bland-Altman agreement between the methods is best when LIC is <20 mg/g dry tissue. Scatter plots show that all values with LIC <20 mg/g dry tissue fall within the 95% prediction limits.
  
  
  CONCLUSIONS
  Liver iron concentration as determined by the R2* and R2 MR methods is statistically comparable, with no statistical difference between these methods for LIC <20 mg/g.
authors.affiliation: Department of Radiology, MLC 5031, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229, USA. suraj.serai@cchmc.org.
authors.forename: Suraj D
authors.initials: SD
authors.lastname: Serai
authors.affiliation: Department of Radiology, MLC 5031, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Fleck
authors.affiliation: Division of Hematology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229, USA.
authors.forename: Charles T
authors.initials: CT
authors.lastname: Quinn
authors.affiliation: Division of Biostatistics and Epidemiology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Nemours Children's Health System Nemours Children's Hospital, Orlando, FL, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Podberesky
mesh_terms: D000293:Adolescent; D000465:Algorithms; D002648:Child; D002675:Child, Preschool; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D019190:Iron Overload / Q000175:diagnosis / Q000378:metabolism*; D008099:Liver / Q000033:anatomy & histology* / Q000378:metabolism*; D008107:Liver Diseases / Q000175:diagnosis / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D057054:Molecular Imaging / Q000379:methods; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
keywords: Adolescents; Chelation therapy; Children; Iron concentration; Liver; Magnetic resonance imaging