title: Comparison of different cardiovascular magnetic resonance sequences for native myocardial T1 mapping at 3T.
abstract: BACKGROUND
  T1 mapping based on cardiovascular magnetic resonance (CMR) is a novel approach using the magnetic relaxation T1 time as a quantitative marker for myocardial tissue composition. Various T1 mapping sequences are being used, with different strengths and weaknesses. Data comparing different sequences head to head however are sparse.
  
  
  METHODS
  We compared three T1 mapping sequences, ShMOLLI, MOLLI and SASHA in phantoms and in a mid-ventricular slice of 40 healthy individuals (mean age 59 ± 7 years, 45 % male) with low (68 %) or moderate cardiovascular risk. We calculated global and segmental T1 in vivo through exponential curve fitting and subsequent parametric mapping. We also analyzed image quality and inter-observer reproducibility.
  
  
  RESULTS
  There was no association of T1 with cardiovascular risk groups. T1 however differed significantly depending on the sequence, with SASHA providing consistently higher mean values than ShMOLLI and MOLLI (1487 ± 36 ms vs. 1174 ± 37 ms and 1199 ± 28 ms, respectively; p < 0.001). This difference between sequences was much smaller in phantom measurements. In patients, segmental values were lower in the anterior wall for all sequences. Image quality, in general good for the steady-state-free-precession readouts in all sequences, was lower for SASHA parametric maps. On multivariate regression analysis, a longer T1 measured by MOLLI was correlated with lower ejection fraction and female gender. Inter-observer variability as assessed by intra-class correlation coefficients was excellent for all sequences (ShMOLLI: 0.995; MOLLI: 0.991; SASHA: 0.961; all p < 0.001).
  
  
  CONCLUSIONS
  In a cross-sectional population with low to moderate cardiovascular risk, we observed a variation in T1 mapping results between inversion-recovery vs. saturation-recovery sequences in vivo, which were less evident in phantom images, despite a small interobserver variability. Thus, physiological factors, most likely related to B1 inhomogeneities, and tissue-specific properties, like magnetization transfer, that impact T1 values in vivo, render phantom validation insufficient, and have to be further investigated for a better understanding of the clinical utility of different T1 mapping approaches.
  
  
  BACKGROUND
  "Canadian Alliance For Healthy Hearts and Minds" - ClinicalTrials.gov NCT02220582 ; registered August 18, 2014.
authors.affiliation: Department of Cardiology, Philippa and Marvin Carsley Cardiovascular MR Centre; Montreal Heart Institute, Université de Montréal, Montréal, Canada. tiagoteixeiranoc@gmail.com.|Centro Hospitalar entre Douro e Vouga, Santa Maria da Feira, Portugal. tiagoteixeiranoc@gmail.com.
authors.forename: Tiago
authors.initials: T
authors.lastname: Teixeira
authors.affiliation: Department of Cardiology, Philippa and Marvin Carsley Cardiovascular MR Centre; Montreal Heart Institute, Université de Montréal, Montréal, Canada.
authors.forename: Tarik
authors.initials: T
authors.lastname: Hafyane
authors.affiliation: Department of Cardiology, Philippa and Marvin Carsley Cardiovascular MR Centre; Montreal Heart Institute, Université de Montréal, Montréal, Canada.|Neuroimaging Research Laboratory and École Polytechnique, Université de Montréal, Montreal, Canada.
authors.forename: Nikola
authors.initials: N
authors.lastname: Stikov
authors.affiliation: Department of Cardiology, Philippa and Marvin Carsley Cardiovascular MR Centre; Montreal Heart Institute, Université de Montréal, Montréal, Canada.
authors.forename: Cansu
authors.initials: C
authors.lastname: Akdeniz
authors.affiliation: Siemens Healthcare GmbH, Erlangen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Greiser
authors.affiliation: Department of Cardiology, Philippa and Marvin Carsley Cardiovascular MR Centre; Montreal Heart Institute, Université de Montréal, Montréal, Canada.|Departments of Medicine and Diagnostic Radiology, McGill University, Montreal, Canada.
authors.forename: Matthias G
authors.initials: MG
authors.lastname: Friedrich
mesh_terms: D000368:Aged; D002318:Cardiovascular Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005260:Female; D064368:Healthy Volunteers; D006321:Heart / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009200:Myocardial Contraction; D015588:Observer Variation; D019047:Phantoms, Imaging; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012307:Risk Factors; D012737:Sex Factors; D013318:Stroke Volume; D016277:Ventricular Function, Left
keywords: MOLLI; Native T1 mapping; Relaxometry; SASHA; ShMOLLI