title: Comparison of 3 T and 1.5 T for T2* magnetic resonance of tissue iron.
abstract: T2* magnetic resonance of tissue iron concentration has improved the outcome of transfusion dependant anaemia patients. Clinical evaluation is performed at 1.5 T but scanners operating at 3 T are increasing in numbers. There is a paucity of data on the relative merits of iron quantification at 3 T vs 1.5 T.
  
  
  
  A total of 104 transfusion dependent anaemia patients and 20 normal volunteers were prospectively recruited to undergo cardiac and liver T2* assessment at both 1.5 T and 3 T. Intra-observer, inter-observer and inter-study reproducibility analysis were performed on 20 randomly selected patients for cardiac and liver T2*.
  
  
  
  Association between heart and liver T2* at 1.5 T and 3 T was non-linear with good fit (R (2) = 0.954, p < 0.001 for heart white-blood (WB) imaging; R (2) = 0.931, p < 0.001 for heart black-blood (BB) imaging; R (2) = 0.993, p < 0.001 for liver imaging). R2* approximately doubled between 1.5 T and 3 T with linear fits for both heart and liver (94, 94 and 105 % respectively). Coefficients of variation for intra- and inter-observer reproducibility, as well as inter-study reproducibility trended to be less good at 3 T (3.5 to 6.5 %) than at 1.5 T (1.4 to 5.7 %) for both heart and liver T2*. Artefact scores for the heart were significantly worse with the 3 T BB sequence (median 4, IQR 2-5) compared with the 1.5 T BB sequence (4 [3-5], p = 0.007).
  
  
  
  Heart and liver T2* and R2* at 3 T show close association with 1.5 T values, but there were more artefacts at 3 T and trends to lower reproducibility causing difficulty in quantifying low T2* values with high tissue iron. Therefore T2* imaging at 1.5 T remains the gold standard for clinical practice. However, in centres where only 3 T is available, equivalent values at 1.5 T may be approximated by halving the 3 T tissue R2* with subsequent conversion to T2*.
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust, London, UK.|Imperial College, London, UK.
authors.forename: Mohammed H
authors.initials: MH
authors.lastname: Alam
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust, London, UK.
authors.forename: Dominique
authors.initials: D
authors.lastname: Auger
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust, London, UK.|Imperial College, London, UK.
authors.forename: Laura-Ann
authors.initials: LA
authors.lastname: McGill
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust, London, UK.|Imperial College, London, UK.
authors.forename: Gillian C
authors.initials: GC
authors.lastname: Smith
authors.affiliation: St George's Hospital, London, UK.
authors.forename: Taigang
authors.initials: T
authors.lastname: He
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust, London, UK.
authors.forename: Cemil
authors.initials: C
authors.lastname: Izgi
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust, London, UK.
authors.forename: A John
authors.initials: AJ
authors.lastname: Baksi
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust, London, UK.
authors.forename: Rick
authors.initials: R
authors.lastname: Wage
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust, London, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Drivas
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust, London, UK.|Imperial College, London, UK.
authors.forename: David N
authors.initials: DN
authors.lastname: Firmin
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust, London, UK. DJ.Pennell@rbht.nhs.uk.|Imperial College, London, UK. DJ.Pennell@rbht.nhs.uk.|Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK. DJ.Pennell@rbht.nhs.uk.
authors.forename: Dudley J
authors.initials: DJ
authors.lastname: Pennell
mesh_terms: D000328:Adult; D000465:Algorithms; D016477:Artifacts; D009202:Cardiomyopathies / Q000175:diagnosis* / Q000378:metabolism; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D005260:Female; D006486:Hemosiderosis / Q000175:diagnosis* / Q000378:metabolism; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007501:Iron / Q000032:analysis*; D016014:Linear Models; D008099:Liver / Q000737:chemistry / Q000000981:diagnostic imaging*; D008107:Liver Diseases / Q000175:diagnosis* / Q000378:metabolism; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000737:chemistry*; D017711:Nonlinear Dynamics; D015588:Observer Variation; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D007501:Iron
keywords: 3 T; Heart; Iron overload; Liver; Magnetic resonance; Siderosis; T2*