title: Does fat suppression via chemically selective saturation affect R2*-MRI for transfusional iron overload assessment? A clinical evaluation at 1.5T and 3T.
abstract: Fat suppression (FS) via chemically selective saturation (CHESS) eliminates fat-water oscillations in multiecho gradient echo (mGRE) R2*-MRI. However, for increasing R2* values as seen with increasing liver iron content (LIC), the water signal spectrally overlaps with the CHESS band, which may alter R2*. We investigated the effect of CHESS on R2* and developed a heuristic correction for the observed CHESS-induced R2* changes.
  
  
  
  Eighty patients [female, n = 49; male, n = 31; mean age (± standard deviation), 18.3 ± 11.7 y] with iron overload were scanned with a non-FS and a CHESS-FS mGRE sequence at 1.5T and 3T. Mean liver R2* values were evaluated using three published fitting approaches. Measured and model-corrected R2* values were compared and statistically analyzed.
  
  
  
  At 1.5T, CHESS led to a systematic R2* reduction (P < 0.001 for all fitting algorithms) especially toward higher R2*. Our model described the observed changes well and reduced the CHESS-induced R2* bias after correction (linear regression slopes: 1.032/0.927/0.981). No CHESS-induced R2* reductions were found at 3T.
  
  
  
  The CHESS-induced R2* bias at 1.5T needs to be considered when applying R2*-LIC biopsy calibrations for clinical LIC assessment, which were established without FS at 1.5T. The proposed model corrects the R2* bias and could therefore improve clinical iron overload assessment based on linear R2*-LIC calibrations. Magn Reson Med 76:591-601, 2016. © 2015 Wiley Periodicals, Inc.
authors: Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors: Axel J
authors: AJ
authors: Krafft
authors: Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors: Ralf B
authors: RB
authors: Loeffler
authors: Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors: Ruitian
authors: R
authors: Song
authors: Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.|Rhodes College, Memphis, Tennessee, USA.
authors: Xiao
authors: X
authors: Bian
authors: Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors: M Beth
authors: MB
authors: McCarville
authors: Department of Hematology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors: Jane S
authors: JS
authors: Hankins
authors: Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors: Claudia M
authors: CM
authors: Hillenbrand
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging* / Q000473:pathology; D000293:Adolescent; D000328:Adult; D000465:Algorithms; D016477:Artifacts; D001803:Blood Transfusion; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007223:Infant; D019190:Iron Overload / Q000000981:diagnostic imaging* / Q000473:pathology; D008107:Liver Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D065227:Transfusion Reaction / Q000000981:diagnostic imaging* / Q000473:pathology; D055815:Young Adult
keywords: R2* quantification; fat suppression (CHESS); hepatic iron overload; liver MRI; quantitative MRI