title: Improved quantitative myocardial T2mapping: Impact of the fitting model.
abstract: OBJECTIVE
  To develop an improved T2prepared (T2prep) balanced steady-state free-precession (bSSFP) sequence and signal relaxation curve fitting method for myocardial T2mapping.
  
  
  METHODS
  Myocardial T2mapping is commonly performed by acquisition of multiple T2prep bSSFP images and estimating the voxel-wise T2values using a two-parameter fit for relaxation. However, a two-parameter fit model does not take into account the effect of imaging pulses in a bSSFP sequence or other imperfections in T2prep RF pulses, which may decrease the robustness of T2mapping. Therefore, we propose a novel T2mapping sequence that incorporates an additional image acquired with saturation preparation, simulating a very long T2prep echo time. This enables the robust estimation of T2maps using a 3-parameter fit model, which captures the effect of imaging pulses and other imperfections. Phantom imaging is performed to compare the T2maps generated using the proposed 3-parameter model with the conventional two-parameter model, as well as a spin echo reference. In vivo imaging is performed on eight healthy subjects to compare the different fitting models.
  
  
  RESULTS
  Phantom and in vivo data show that the T2values generated by the proposed 3-parameter model fitting do not change with different choices of the T2prep echo times, and are not statistically different than the reference values for the phantom (P = 0.10 with three T2prep echoes). The two-parameter model exhibits dependence on the choice of T2prep echo times and are significantly different than the reference values (P = 0.01 with three T2prep echoes).
  
  
  CONCLUSIONS
  The proposed imaging sequence in combination with a three-parameter model allows accurate measurement of myocardial T2values, which is independent of number and duration of T2prep echo times. Magn Reson Med 74:93-105, 2015. © 2014 Wiley Periodicals, Inc.
authors.affiliation: Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Akçakaya
authors.affiliation: Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Tamer A
authors.initials: TA
authors.lastname: Basha
authors.affiliation: Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.|Computer Assisted Clinical Medicine, University Medical Center Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Weingärtner
authors.affiliation: Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Roujol
authors.affiliation: Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Sophie
authors.initials: S
authors.lastname: Berg
authors.affiliation: Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Reza
authors.initials: R
authors.lastname: Nezafat
keywords: myocardial T2 mapping; myocardial inflammation; quantitative myocardial tissue characterization; three-parameter fit
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