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Subcortical gray matter segmentation and voxel‐based analysis using transverse relaxation and quantitative susceptibility mapping with application to multiple sclerosis
Author(s) -
Cobzas Dana,
Sun Hongfu,
Walsh Andrew J.,
Lebel R. Marc,
Blevins Gregg,
Wilman Alan H.
Publication year - 2015
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.24951
Subject(s) - voxel , globus pallidus , putamen , nuclear medicine , segmentation , quantitative susceptibility mapping , voxel based morphometry , magnetic resonance imaging , white matter , nuclear magnetic resonance , artificial intelligence , medicine , physics , computer science , basal ganglia , radiology , central nervous system , endocrinology
Purpose To investigate subcortical gray matter segmentation using transverse relaxation rate ( R 2 *) and quantitative susceptibility mapping (QSM) and apply it to voxel‐based analysis in multiple sclerosis (MS). Materials and Methods Voxel‐based variation in R 2 * and QSM within deep gray matter was examined and compared to standard whole‐structure analysis using 37 MS subjects and 37 matched controls. Deep gray matter nuclei (caudate, putamen, globus pallidus, and thalamus) were automatically segmented and morphed onto a custom atlas based on QSM and standard T 1 ‐weighted images. Segmentation accuracy and scan–rescan reliability were tested. Results When considering only significant regions as returned by the multivariate voxel‐based analysis, increased R 2 * and QSM was found in MS subjects compared to controls in portions of all four nuclei studied ( P < 0.002). For R 2 *, regional analysis yielded at least 66‐fold improved P ‐value significance in all nuclei over standard whole‐structure analysis, while for QSM only thalamus benefited, with 5‐fold improvement in significance. Improved segmentation over standard methods, particularly for globus pallidus (2.8 times higher Dice score), was achieved by incorporating high‐contrast QSM into the atlas. Voxel‐based reliability was highest for QSM (<1% variation). Conclusion Automatic segmentation of iron‐rich deep gray matter can be improved by incorporating QSM. Voxel‐based evaluation yielded increased R 2 * and QSM in MS subjects in all four nuclei studied with R 2 *, benefiting the most from localized analysis over whole‐structure measures. J. MAGN. RESON. IMAGING 2015;42:1601–1610.