title: The effect of changes to MOLLI scheme on T1 mapping and extra cellular volume calculation in healthy volunteers with 3 tesla cardiovascular magnetic resonance imaging.
abstract: BACKGROUND
  Diffuse myocardial fibrosis may be quantified with magnetic resonance (MR) by calculating extracellular volume (ECV) fraction from native and post-contrast T1 values. The ideal modified look-locker inversion recovery (MOLLI) sequence for deriving T1 values has not been determined. This study aims to establish if systematic differences exist between suggested MOLLI schemes.
  
  
  METHODS
  Twelve phantom gels were studied with inversion recovery spin echo MR at 3.0 tesla to determine reference T1. Gels were then scanned with six MOLLI sequences (3s)3b(3s)5b; 4b(3s)3b(3s)2b; 5b(3s)3b with flip angles of both 35° and 50° at a range of heart rates (HRs). In 10 healthy volunteers MOLLI studies were performed on two separate occasions. Mid ventricular native and post contrast T1 was measured and ECV (%) calculated.
  
  
  RESULTS
  In phantoms, the co-efficient of variability at simulated HR [40-100] with a flip angle of 35° ranged from 6.77 to 9.55, and at 50° from 7.71 to 11.10. T1 was under-estimated by all MOLLI acquisitions. Error was greatest with longer T1, and increased as HR increased. The 10 volunteers had normal MR studies. Native T1 time was similar for all acquisitions but highest with the 5b(3s)3b 35° scheme (1,189.1±33.46 ms). Interstudy reproducibility was similar for all MOLLIs.
  
  
  CONCLUSIONS
  The 5b(3s)3b MOLLI scheme agreed best with reference T1, without statistical difference between the six schemes. The shorter breath-hold time of 5b(3s)3b scheme may be preferable in clinical studies and warrants further investigation.
authors.affiliation: 1 Multidisciplinary Cardiovascular Research Centre (MCRC) & Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK ; 2 Philips Healthcare, Philips Centre, Guildford Business Park, Guildford, UK.
authors.forename: Adam K
authors.initials: AK
authors.lastname: McDiarmid
authors.affiliation: 1 Multidisciplinary Cardiovascular Research Centre (MCRC) & Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK ; 2 Philips Healthcare, Philips Centre, Guildford Business Park, Guildford, UK.
authors.forename: David A
authors.initials: DA
authors.lastname: Broadbent
authors.affiliation: 1 Multidisciplinary Cardiovascular Research Centre (MCRC) & Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK ; 2 Philips Healthcare, Philips Centre, Guildford Business Park, Guildford, UK.
authors.forename: David M
authors.initials: DM
authors.lastname: Higgins
authors.affiliation: 1 Multidisciplinary Cardiovascular Research Centre (MCRC) & Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK ; 2 Philips Healthcare, Philips Centre, Guildford Business Park, Guildford, UK.
authors.forename: Peter P
authors.initials: PP
authors.lastname: Swoboda
authors.affiliation: 1 Multidisciplinary Cardiovascular Research Centre (MCRC) & Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK ; 2 Philips Healthcare, Philips Centre, Guildford Business Park, Guildford, UK.
authors.forename: Ananth
authors.initials: A
authors.lastname: Kidambi
authors.affiliation: 1 Multidisciplinary Cardiovascular Research Centre (MCRC) & Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK ; 2 Philips Healthcare, Philips Centre, Guildford Business Park, Guildford, UK.
authors.forename: David P
authors.initials: DP
authors.lastname: Ripley
authors.affiliation: 1 Multidisciplinary Cardiovascular Research Centre (MCRC) & Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK ; 2 Philips Healthcare, Philips Centre, Guildford Business Park, Guildford, UK.
authors.forename: Bara
authors.initials: B
authors.lastname: Erhayiem
authors.affiliation: 1 Multidisciplinary Cardiovascular Research Centre (MCRC) & Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK ; 2 Philips Healthcare, Philips Centre, Guildford Business Park, Guildford, UK.
authors.forename: Tarique A
authors.initials: TA
authors.lastname: Musa
authors.affiliation: 1 Multidisciplinary Cardiovascular Research Centre (MCRC) & Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK ; 2 Philips Healthcare, Philips Centre, Guildford Business Park, Guildford, UK.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Dobson
authors.affiliation: 1 Multidisciplinary Cardiovascular Research Centre (MCRC) & Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK ; 2 Philips Healthcare, Philips Centre, Guildford Business Park, Guildford, UK.
authors.forename: John P
authors.initials: JP
authors.lastname: Greenwood
authors.affiliation: 1 Multidisciplinary Cardiovascular Research Centre (MCRC) & Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK ; 2 Philips Healthcare, Philips Centre, Guildford Business Park, Guildford, UK.
authors.forename: Sven
authors.initials: S
authors.lastname: Plein
keywords: T1 mapping; cardiovascular magnetic resonance imaging (MRI); modified look-locker inversion recovery (MOLLI)