title: Liver iron overload assessment by MRI R2* relaxometry in highly transfused pediatric patients: an agreement and reproducibility study.
abstract: OBJECTIVE
  Perform an agreement and reproducibility study of the estimation of iron overload in highly transfused pediatric patients comparing R2* relaxometry (R2*=1000/T2*) to the reference technique liver/muscle signal intensity ratio (SIR).
  
  
  METHODS
  Ninety-two MRI were performed in 68 children who were mainly transfused for sickle cell disease, mean age 9.9 years old. The examination included six sequences for the SIR protocol and a single multiecho T2* sequence. R2* relaxometry was measured by two radiologists independently, either by a region of interest (ROI) in the right liver, or an outline of the whole liver. Hepatic iron load was determined by the Wood formula (Fe mg/g=R2*×0.0254+0.202). The validity of R2* relaxometry compared to SIR was evaluated by the coefficient of variation and the quadratic weighted Kappa value.
  
  
  RESULTS
  The correlation between R2* relaxometry and SIR was very good with a Pearson coefficient of 0.89 and a coefficient of variation of 17.3%. The inter- and intraobserver reproducibility of the measurement of R2* relaxometry by ROI and whole liver mapping was excellent. However, we observed a common positive variation of one class between SIR and R2* relaxometry, with higher hepatic iron content values with SIR than with R2* relaxometry.
  
  
  CONCLUSIONS
  Hepatic iron content can be rapidly and precisely estimated on MRI by multiecho gradient-echo sequences.
authors.affiliation: Service d'imagerie médicale, centre de référence de la drépanocytose, centre hospitalier intercommunal de Créteil, 40, avenue de Verdun, 94010 Créteil cedex, France. Electronic address: suzanne.verlhac@chicreteil.fr.
authors.forename: S
authors.initials: S
authors.lastname: Verlhac
authors.affiliation: Service d'imagerie médicale, centre de référence de la drépanocytose, centre hospitalier intercommunal de Créteil, 40, avenue de Verdun, 94010 Créteil cedex, France.
authors.forename: M
authors.initials: M
authors.lastname: Morel
authors.affiliation: Service de pédiatrie, centre de référence pédiatrique de la drépanocytose, université Paris Est-Créteil, centre hospitalier intercommunal de Créteil, 40, avenue de Verdun, 94010 Créteil cedex, France.
authors.forename: F
authors.initials: F
authors.lastname: Bernaudin
authors.affiliation: Association clinique et thérapeutique infantile du Val-de-Marne (ACTIV), 94100 Saint-Maur des Fossés, France.
authors.forename: S
authors.initials: S
authors.lastname: Béchet
authors.affiliation: Centre de recherche clinique, centre hospitalier intercommunal de Créteil, 40, avenue de Verdun, 94010 Créteil cedex, France.
authors.forename: C
authors.initials: C
authors.lastname: Jung
authors.affiliation: Service d'imagerie médicale, centre de référence de la drépanocytose, centre hospitalier intercommunal de Créteil, 40, avenue de Verdun, 94010 Créteil cedex, France.
authors.forename: M
authors.initials: M
authors.lastname: Vasile
mesh_terms: D000293:Adolescent; D000755:Anemia, Sickle Cell / Q000628:therapy; D001803:Blood Transfusion; D002648:Child; D002675:Child, Preschool; D006801:Humans; D019190:Iron Overload / Q000150:complications / Q000175:diagnosis*; D008099:Liver / Q000473:pathology; D008107:Liver Diseases / Q000150:complications / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D018482:Muscle, Skeletal / Q000473:pathology; D015203:Reproducibility of Results; D055815:Young Adult
keywords: Iron overload; Liver MRI; Sickle cell disease