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Single‐shot T 1 mapping using simultaneous acquisitions of spin‐ and stimulated‐echo‐planar imaging (2D ss‐SESTEPI)
Author(s) -
Shi Xianfeng,
Kim SeongEun,
Jeong EunKee
Publication year - 2010
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.22367
Subject(s) - spin echo , planar , nuclear magnetic resonance , amplitude , transverse plane , echo planar imaging , physics , echo (communications protocol) , magnetization , diffusion , optics , magnetic resonance imaging , magnetic field , computer science , medicine , computer network , structural engineering , quantum mechanics , radiology , engineering , computer graphics (images) , thermodynamics
Abstract The conventional stimulated‐echo NMR sequence only measures the longitudinal component while discarding the transverse component, after tipping up the prepared magnetization. This transverse magnetization can be used to measure a spin echo, in addition to the stimulated echo. Two‐dimensional single‐shot spin‐ and stimulated‐echo‐planar imaging (ss‐SESTEPI) is an echo‐planar‐imaging‐based single‐shot imaging technique that simultaneously acquires a spin‐echo‐planar image and a stimulated‐echo‐planar image after a single radiofrequency excitation. The magnitudes of the spin‐echo‐planar image and stimulated‐echo‐planar image differ by T 1 decay and diffusion weighting for perfect 90° radiofrequency and thus can be used to rapidly measure T 1 . However, the spatial variation of amplitude of radiofrequency field induces uneven splitting of the transverse magnetization for the spin‐echo‐planar image and stimulated‐echo‐planar image within the imaging field of view. Correction for amplitude of radiofrequency field inhomogeneity is therefore critical for two‐dimensional ss‐SESTEPI to be used for T 1 measurement. We developed a method for amplitude of radiofrequency field inhomogeneity correction by acquiring an additional stimulated‐echo‐planar image with minimal mixing time, calculating the difference between the spin echo and the stimulated echo and multiplying the stimulated‐echo‐planar image by the inverse functional map. Diffusion‐induced decay is corrected by measuring the average diffusivity during the prescanning. Rapid single‐shot T 1 mapping may be useful for various applications, such as dynamic T 1 mapping for real‐time estimation of the concentration of contrast agent in dynamic contrast enhancement MRI. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.