title: Myocardial T1-mapping at 3T using saturation-recovery: reference values, precision and comparison with MOLLI.
abstract: BACKGROUND
  Myocardial T1-mapping recently emerged as a promising quantitative method for non-invasive tissue characterization in numerous cardiomyopathies. Commonly performed with an inversion-recovery (IR) magnetization preparation at 1.5T, the application at 3T has gained due to increased quantification precision. Alternatively, saturation-recovery (SR) T1-mapping has recently been introduced at 1.5T for improved accuracy. Thus, the purpose of this study is to investigate the robustness and precision of SR T1-mapping at 3T and to establish accurate reference values for native T1-times and extracellular volume fraction (ECV) of healthy myocardium.
  
  
  METHODS
  Balanced Steady-State Free-Precession (bSSFP) Saturation-Pulse Prepared Heart-rate independent Inversion-REcovery (SAPPHIRE) and Saturation-recovery Single-SHot Acquisition (SASHA) T1-mapping were compared with the Modified Look-Locker inversion recovery (MOLLI) sequence at 3T. Accuracy and precision were studied in phantom. Native and post-contrast T1-times and regional ECV were determined in 20 healthy subjects (10 men, 27 ± 5 years). Subjective image quality, susceptibility artifact rating, in-vivo precision and reproducibility were analyzed.
  
  
  RESULTS
  SR T1-mapping showed <4 % deviation from the spin-echo reference in phantom in the range of T1= 100-2300 ms. The average quality and artifact scores of the T1-mapping methods were: MOLLI:3.4/3.6, SAPPHIRE:3.1/3.4, SASHA:2.9/3.2; (1: poor - 4: excellent/1: strong - 4: none). SAPPHIRE and SASHA yielded significantly higher T1-times (SAPPHIRE: 1578 ± 42 ms, SASHA: 1523 ± 46 ms), in-vivo T1-time variation (SAPPHIRE: 60.1 ± 8.7 ms, SASHA: 70.0 ± 9.3 ms) and lower ECV-values (SAPPHIRE: 0.20 ± 0.02, SASHA: 0.21 ± 0.03) compared with MOLLI (T1: 1181 ± 47 ms, ECV: 0.26 ± 0.03, Precision: 53.7 ± 8.1 ms). No significant difference was found in the inter-subject variability of T1-times or ECV-values (T1: p = 0.90, ECV: p = 0.78), the observer agreement (inter: p > 0.19; intra: p > 0.09) or consistency (inter: p > 0.07; intra: p > 0.17) between the three methods.
  
  
  CONCLUSIONS
  Saturation-recovery T1-mapping at 3T yields higher accuracy, comparable inter-subject, inter- and intra-observer variability and less than 30 % precision-loss compared to MOLLI.
authors.affiliation: Computer Assisted Clinical Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany. sebastian.weingaertner@medma.uni-heidelberg.de.|Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, USA. sebastian.weingaertner@medma.uni-heidelberg.de.|Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA. sebastian.weingaertner@medma.uni-heidelberg.de.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Weingärtner
authors.affiliation: Computer Assisted Clinical Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.|DZHK (German Centre for Cardiovascular Research) partner site Heidelberg/Mannheim, Mannheim, Germany.
authors.forename: Nadja M
authors.initials: NM
authors.lastname: Meßner
authors.affiliation: Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Budjan
authors.affiliation: 1st Department of Medicine Cardiology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Loßnitzer
authors.affiliation: Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Mattler
authors.affiliation: DZHK (German Centre for Cardiovascular Research) partner site Heidelberg/Mannheim, Mannheim, Germany.|1st Department of Medicine Cardiology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: Theano
authors.initials: T
authors.lastname: Papavassiliu
authors.affiliation: Computer Assisted Clinical Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.
authors.forename: Frank G
authors.initials: FG
authors.lastname: Zöllner
authors.affiliation: Computer Assisted Clinical Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.
authors.forename: Lothar R
authors.initials: LR
authors.lastname: Schad
mesh_terms: D000328:Adult; D016477:Artifacts; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D064368:Healthy Volunteers; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods* / Q000592:standards; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D008297:Male; D008536:Meglumine / Q000008:administration & dosage; D009206:Myocardium; D015588:Observer Variation; D009942:Organometallic Compounds / Q000008:administration & dosage; D019047:Phantoms, Imaging; D011237:Predictive Value of Tests; D012016:Reference Values; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D008536:Meglumine; C072417:gadoterate meglumine
keywords: 3T; Cardiovascular magnetic resonance; MOLLI; Reference values; SAPPHIRE; SASHA; Saturation-recovery T1-mapping