title: T1 at 1.5T and 3T compared with conventional T2* at 1.5T for cardiac siderosis.
abstract: BACKGROUND
  Myocardial black blood (BB) T2* relaxometry at 1.5T provides robust, reproducible and calibrated non-invasive assessment of cardiac iron burden. In vitro data has shown that like T2*, novel native Modified Look-Locker Inversion recovery (MOLLI) T1 shortens with increasing tissue iron. The relative merits of T1 and T2* are largely unexplored. We compared the established 1.5T BB T2* technique against native T1 values at 1.5T and 3T in iron overload patients and in normal volunteers.
  
  
  METHODS
  A total of 73 subjects (42 male) were recruited, comprising 20 healthy volunteers (controls) and 53 patients (thalassemia major 22, sickle cell disease 9, hereditary hemochromatosis 9, other iron overload conditions 13). Single mid-ventricular short axis slices were acquired for BB T2* at 1.5T and MOLLI T1 quantification at 1.5T and 3T.
  
  
  RESULTS
  In healthy volunteers, median T1 was 1014 ms (full range 939-1059 ms) at 1.5T and modestly increased to 1165ms (full range 1056-1224 ms) at 3T. All patients with significant cardiac iron overload (1.5T T2* values <20 ms) had T1 values <939 ms at 1.5T, and <1056 ms at 3T. Associations between T2* and T1 were found to be moderate with y =377 · x(0.282) at 1.5T (R(2) = 0.717), and y =406 · x(0.294) at 3T (R(2) = 0.715). Measures of reproducibility of T1 appeared superior to T2*.
  
  
  CONCLUSIONS
  T1 mapping at 1.5T and at 3T can identify individuals with significant iron loading as defined by the current gold standard T2* at 1.5T. However, there is significant scatter between results which may reflect measurement error, but it is also possible that T1 interacts with T2*, or is differentially sensitive to aspects of iron chemistry or other biology. Hurdles to clinical implementation of T1 include the lack of calibration against human myocardial iron concentration, no demonstrated relation to cardiac outcomes, and variation in absolute T1 values between scanners, which makes inter-centre comparisons difficult. The relative merits of T1 at 3T versus T2* at 3T require further consideration.
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK. M.Alam@rbht.nhs.uk.|Imperial College London, London, UK. M.Alam@rbht.nhs.uk.
authors.forename: Mohammed H
authors.initials: MH
authors.lastname: Alam
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK. D.Auger@rbht.nhs.uk.|Imperial College London, London, UK. D.Auger@rbht.nhs.uk.
authors.forename: Dominique
authors.initials: D
authors.lastname: Auger
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK. G.Smith@rbht.nhs.uk.|Imperial College London, London, UK. G.Smith@rbht.nhs.uk.
authors.forename: Gillian C
authors.initials: GC
authors.lastname: Smith
authors.affiliation: St George's, University of London, London, UK. tgheuk@gmail.com.
authors.forename: Taigang
authors.initials: T
authors.lastname: He
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK. V.Vassiliou@rbht.nhs.uk.|Imperial College London, London, UK. V.Vassiliou@rbht.nhs.uk.
authors.forename: Vassilis
authors.initials: V
authors.lastname: Vassiliou
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK. J.Baksi@rbht.nhs.uk.|Imperial College London, London, UK. J.Baksi@rbht.nhs.uk.
authors.forename: A John
authors.initials: AJ
authors.lastname: Baksi
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK. R.Wage@rbht.nhs.uk.
authors.forename: Rick
authors.initials: R
authors.lastname: Wage
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK. Peter_Drivas@live.co.uk.
authors.forename: Peter
authors.initials: P
authors.lastname: Drivas
authors.affiliation: School of Biomedical Engineering, Southern Medical University, Guangzhou, China. chenwf@fimmu.com.
authors.forename: Yanqiu
authors.initials: Y
authors.lastname: Feng
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK. D.Firmin@rbht.nhs.uk.|Imperial College London, London, UK. D.Firmin@rbht.nhs.uk.
authors.forename: David N
authors.initials: DN
authors.lastname: Firmin
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK. DJ.Pennell@rbht.nhs.uk.|Imperial College London, London, UK. DJ.Pennell@rbht.nhs.uk.
authors.forename: Dudley J
authors.initials: DJ
authors.lastname: Pennell
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D009202:Cardiomyopathies / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007501:Iron / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D015203:Reproducibility of Results; D012806:Siderosis / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D055815:Young Adult
chemical_list: D015415:Biomarkers; D007501:Iron