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Time‐efficient, high‐resolution, whole brain three‐dimensional macromolecular proton fraction mapping
Author(s) -
Yarnykh Vasily L.
Publication year - 2016
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.25811
Subject(s) - magnetization transfer , voxel , white matter , nuclear magnetic resonance , resolution (logic) , nuclear medicine , physics , computer science , artificial intelligence , magnetic resonance imaging , medicine , radiology
Purpose Macromolecular proton fraction (MPF) mapping is a quantitative MRI method that reconstructs parametric maps of a relative amount of macromolecular protons causing the magnetization transfer (MT) effect and provides a biomarker of myelination in neural tissues. This study aimed to develop a high‐resolution whole brain MPF mapping technique using a minimal number of source images for scan time reduction. Methods The described technique was based on replacement of an actually acquired reference image without MT saturation by a synthetic one reconstructed from R 1 and proton density maps, thus requiring only three source images. This approach enabled whole brain three‐dimensional MPF mapping with isotropic 1.25 × 1.25 × 1.25 mm 3 voxel size and a scan time of 20 min. The synthetic reference method was validated against standard MPF mapping with acquired reference images based on data from eight healthy subjects. Results Mean MPF values in segmented white and gray matter appeared in close agreement with no significant bias and small within‐subject coefficients of variation (<2%). High‐resolution MPF maps demonstrated sharp white–gray matter contrast and clear visualization of anatomical details, including gray matter structures with high iron content. Conclusions The proposed synthetic reference method improves resolution of MPF mapping and combines accurate MPF measurements with unique neuroanatomical contrast features. Magn Reson Med 75:2100–2106, 2016. © 2015 Wiley Periodicals, Inc.