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Applications of stimulated echo correction to multicomponent T 2 analysis
Author(s) -
Prasloski Thomas,
Mädler Burkhard,
Xiang QingSan,
MacKay Alex,
Jones Craig
Publication year - 2012
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.23157
Subject(s) - flip angle , voxel , reproducibility , homogeneity (statistics) , coherence (philosophical gambling strategy) , algorithm , physics , nuclear magnetic resonance , computer science , mathematics , artificial intelligence , statistics , magnetic resonance imaging , medicine , radiology
We propose a multicomponent fitting algorithm for multiecho T 2 data which allows for correction of T 2 distributions in the presence of stimulated echoes. Tracking the population of spins in many coherence pathways via the iterated method of the Extended Phase Graph algorithm allows for accurate quantification of echo magnitudes. The resulting decay curves allow for correction of errors due to nonideal refocusing pulses as a result of inhomogeneities in the B 1 transmit field. Non‐Negative Least Squares fitting is used to quantify the magnitude of T 2 components at various T 2 values. This method, allowing calculation of the T 2 distribution with simultaneous extraction of the refocusing pulse flip angle, requires no change to image acquisition procedures and no extra data input. Validation by means of both simulations and in vivo data shows excellent interscan reproducibility while vastly improving the accuracy of extracted T 2 parameters in voxels where poor B 1 homogeneity leads to refocusing pulse flip angles significantly less than 180°. Most notably, myelin water fraction values in these regions are found to have increased consistency and accuracy. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.