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Improved quantitative myocardial T 2 mapping: Impact of the fitting model
Author(s) -
Akçakaya Mehmet,
Basha Tamer A.,
Weingärtner Sebastian,
Roujol Sébastien,
Berg Sophie,
Nezafat Reza
Publication year - 2015
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.25377
Subject(s) - imaging phantom , voxel , t2 relaxation , robustness (evolution) , estimation theory , computer science , nuclear magnetic resonance , algorithm , artificial intelligence , magnetic resonance imaging , physics , optics , medicine , radiology , chemistry , biochemistry , gene
Purpose To develop an improved T 2 prepared (T 2 prep) balanced steady‐state free‐precession (bSSFP) sequence and signal relaxation curve fitting method for myocardial T 2 mapping. Methods Myocardial T 2 mapping is commonly performed by acquisition of multiple T 2 prep bSSFP images and estimating the voxel‐wise T 2 values 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 T 2 prep RF pulses, which may decrease the robustness of T 2 mapping. Therefore, we propose a novel T 2 mapping sequence that incorporates an additional image acquired with saturation preparation, simulating a very long T 2 prep echo time. This enables the robust estimation of T 2 maps using a 3‐parameter fit model, which captures the effect of imaging pulses and other imperfections. Phantom imaging is performed to compare the T 2 maps 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 T 2 values generated by the proposed 3‐parameter model fitting do not change with different choices of the T 2 prep echo times, and are not statistically different than the reference values for the phantom ( P = 0.10 with three T 2 prep echoes). The two‐parameter model exhibits dependence on the choice of T 2 prep echo times and are significantly different than the reference values ( P = 0.01 with three T 2 prep echoes). Conclusion The proposed imaging sequence in combination with a three‐parameter model allows accurate measurement of myocardial T 2 values, which is independent of number and duration of T 2 prep echo times. Magn Reson Med 74:93–105, 2015. © 2014 Wiley Periodicals, Inc.