title: Native T1 mapping: inter-study, inter-observer and inter-center reproducibility in hemodialysis patients.
abstract: BACKGROUND
  Native T1 mapping is a cardiovascular magnetic resonance (CMR) technique that associates with markers of fibrosis and strain in hemodialysis patients. The reproducibility of T1 mapping in hemodialysis patients, prone to changes in fluid status, is unknown. Accurate quantification of myocardial fibrosis in this population has prognostic potential.
  
  
  METHODS
  Using 3 Tesla CMR, we report the results of 1) the inter-study, inter-observer and intra-observer reproducibility of native T1 mapping in 10 hemodialysis patients; 2) inter-study reproducibility of left ventricular (LV) structure and function in 10 hemodialysis patients; 3) the agreement of native T1 map and native T1 phantom analyses between two centres in 20 hemodialysis patients; 4) the effect of changes in markers of fluid status on native T1 values in 10 hemodialysis patients.
  
  
  RESULTS
  Inter-study, inter-observer and intra-observer variability of native T1 mapping were excellent with co-efficients of variation (CoV) of 0.7, 0.3 and 0.4% respectively. Inter-study CoV for LV structure and function were: LV mass = 1%; ejection fraction = 1.1%; LV end-diastolic volume = 5.2%; LV end-systolic volume = 5.6%. Inter-centre variability of analysis techniques were excellent with CoV for basal and mid-native T1 slices between 0.8-1.2%. Phantom analyses showed comparable native T1 times between centres, despite different scanners and acquisition sequences (centre 1: 1192.7 ± 7.5 ms, centre 2: 1205.5 ± 5 ms). For the 10 patients who underwent inter-study testing, change in body weight (Δweight) between scans correlated with change in LV end-diastolic volume (ΔLVEDV) (r = 0.682;P = 0.03) representing altered fluid status between scans. There were no correlations between change in native T1 between scans (ΔT1) and ΔLVEDV or Δweight (P > 0.6). Linear regression confirmed ΔT1 was unaffected by ΔLVEDV or Δweight (P > 0.59).
  
  
  CONCLUSIONS
  Myocardial native T1 is reproducible in HD patients and unaffected by changes in fluid status at the levels we observed. Native T1 mapping is a potential imaging biomarker for myocardial fibrosis in patients with end-stage renal disease.
authors.affiliation: John Walls Renal Unit, University Hospitals Leicester NHS Trust, Leicester, UK. mpmgb1@le.ac.uk.|Department of Infection Immunity and Inflammation, School of Medicine and Biological Sciences, University of Leicester, Leicester, LE1 9HN, UK. mpmgb1@le.ac.uk.|National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK. mpmgb1@le.ac.uk.
authors.forename: Matthew P M
authors.initials: MP
authors.lastname: Graham-Brown
authors.affiliation: BHF Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, 126 University Place, Glasgow, UK.|The Glasgow Renal & Transplant Unit, Queen Elizabeth University Hospital, 1345 Govan Road, Glasgow, UK.
authors.forename: Elaine
authors.initials: E
authors.lastname: Rutherford
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester and NIHR Leicester Cardiovascular Biomedical Research Unit, Glenfield Hospital Leicester, Leicester, UK.
authors.forename: E
authors.initials: E
authors.lastname: Levelt
authors.affiliation: John Walls Renal Unit, University Hospitals Leicester NHS Trust, Leicester, UK.|Department of Infection Immunity and Inflammation, School of Medicine and Biological Sciences, University of Leicester, Leicester, LE1 9HN, UK.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: March
authors.affiliation: John Walls Renal Unit, University Hospitals Leicester NHS Trust, Leicester, UK.|Department of Infection Immunity and Inflammation, School of Medicine and Biological Sciences, University of Leicester, Leicester, LE1 9HN, UK.
authors.forename: Darren R
authors.initials: DR
authors.lastname: Churchward
authors.affiliation: National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Stensel
authors.affiliation: BHF Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, 126 University Place, Glasgow, UK.|Clinical Physics, NHS Greater Glasgow and Clyde, Glasgow, UK.
authors.forename: Christie
authors.initials: C
authors.lastname: McComb
authors.affiliation: BHF Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, 126 University Place, Glasgow, UK.|West of Scotland Heart and Lung Centre, Golden Jubilee National Hospital, Clydebank, UK.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Mangion
authors.affiliation: BHF Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, 126 University Place, Glasgow, UK.
authors.forename: Samantha
authors.initials: S
authors.lastname: Cockburn
authors.affiliation: BHF Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, 126 University Place, Glasgow, UK.|West of Scotland Heart and Lung Centre, Golden Jubilee National Hospital, Clydebank, UK.
authors.forename: Colin
authors.initials: C
authors.lastname: Berry
authors.affiliation: UCL Institute of Cardiovascular Science, University College London, London, UK.
authors.forename: James C
authors.initials: JC
authors.lastname: Moon
authors.affiliation: BHF Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, 126 University Place, Glasgow, UK.|The Glasgow Renal & Transplant Unit, Queen Elizabeth University Hospital, 1345 Govan Road, Glasgow, UK.
authors.forename: Patrick B
authors.initials: PB
authors.lastname: Mark
authors.affiliation: John Walls Renal Unit, University Hospitals Leicester NHS Trust, Leicester, UK.|Department of Infection Immunity and Inflammation, School of Medicine and Biological Sciences, University of Leicester, Leicester, LE1 9HN, UK.|Department of Cardiovascular Sciences, University of Leicester and NIHR Leicester Cardiovascular Biomedical Research Unit, Glenfield Hospital Leicester, Leicester, UK.
authors.forename: James O
authors.initials: JO
authors.lastname: Burton
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester and NIHR Leicester Cardiovascular Biomedical Research Unit, Glenfield Hospital Leicester, Leicester, UK.
authors.forename: Gerry P
authors.initials: GP
authors.lastname: McCann
mesh_terms: D000328:Adult; D000368:Aged; D009202:Cardiomyopathies / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D005260:Female; D005355:Fibrosis; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D016014:Linear Models; D019028:Magnetic Resonance Imaging, Cine / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology*; D015588:Observer Variation; D019047:Phantoms, Imaging; D011237:Predictive Value of Tests; D006435:Renal Dialysis; D015203:Reproducibility of Results; D012307:Risk Factors; D006113:United Kingdom; D014882:Water-Electrolyte Balance
keywords: Cardiovascular magnetic resonance; Hemodialysis; Myocardial fibrosis; Native T1; Reproducibility