title: Myocardial and hepatic iron overload assessment by region-based and pixel-wise T2* mapping analysis: technical pitfalls and clinical warnings.
abstract: OBJECTIVE
  The aim of this study was to compare myocardial T2* assessment with region-based (RB) T2* multiecho technique (CMRtools) with the pixel-wise (PW) inline myocardial T2* mapping (Siemens) in patients with thalassemia major for myocardial iron characterization.
  
  
  METHODS
  Forty-three thalassemia major patients were examined on a 1.5-T scanner using conventional gradient multiecho sequence. All the images were analyzed using both RB and PW T2* mapping. Coefficients of reproducibility (CRs) were used to assess the interoperator and intraobserver variability of each software.
  
  
  RESULTS
  The mean (SD) myocardial T2* values using RB and PW software resulted significantly different (30.7 [15] milliseconds [range, 4.8-52.6 milliseconds] vs 24.3 [10.5] milliseconds [range 4.6-38.2 milliseconds]; P < 0.0001). Interestingly, we found that SD had exponential relationship with T2* with evidence of increase in SD for T2* values greater than 20 milliseconds. For myocardial T2* values less than 20 milliseconds, intraobserver CR was 1.2 milliseconds for RB and 1.8 milliseconds for PW T2* mapping, and the interoperator CR was 3.4 and 1.6 milliseconds for RB and PW T2* mapping, respectively. Comparing iron overload classification by both software, we found that 7 patients (16%) were differently categorized using the standard T2* thresholds.
  
  
  CONCLUSIONS
  Our data show that RB and PW T2* mapping can be used interchangeably to measure severe myocardial and hepatic iron overload, whereas for borderline T2* values, we observed differences among the 2 methods causing different categorization.
authors.affiliation: From the *CMR Unit, Department of Cardiology and Cardiac Surgery, Niguarda Ca' Granda Hospital; †Rare Diseases Center, Department of Medicine and Medical Specialities, Ca' Granda Foundation Ospedale Maggiore Policlinico IRCCS; and ‡Department of Clinical Sciences and Community Health, Ca' Granda Foundation Ospedale Maggiore Policlinico IRCCS, University of Milan, Milan, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Roghi
authors.forename: Erika
authors.initials: E
authors.lastname: Poggiali
authors.forename: Patrizia
authors.initials: P
authors.lastname: Pedrotti
authors.forename: Angela
authors.initials: A
authors.lastname: Milazzo
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Quattrocchi
authors.forename: Elena
authors.initials: E
authors.lastname: Cassinerio
authors.forename: Maria Domenica
authors.initials: MD
authors.lastname: Cappellini
mesh_terms: D000328:Adult; D000465:Algorithms; D009202:Cardiomyopathies / Q000473:pathology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019190:Iron Overload / Q000473:pathology*; D008107:Liver Diseases / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017086:beta-Thalassemia / Q000473:pathology*