Subcortical gray matter segmentation and voxel-based analysis using transverse relaxation and quantitative susceptibility mapping with application to multiple sclerosis

• Published in: Journal of magnetic resonance imaging Vol. 42; no. 6; pp. 1601 - 1610
• Main Authors: Cobzas, Dana, Sun, Hongfu, Walsh, Andrew J., Lebel, R. Marc, Blevins, Gregg, Wilman, Alan H.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.12.2015; Wiley Subscription Services, Inc
• Subjects: Adult; Algorithms; Brain - pathology; brain iron; Female; Gray Matter - pathology; Humans; Image Enhancement - methods; Image Interpretation, Computer-Assisted - methods; Imaging, Three-Dimensional - methods; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Male; Middle Aged; Multiple sclerosis; Multiple Sclerosis - pathology; Pattern Recognition, Automated - methods; quantitative susceptibility mapping; Reproducibility of Results; segmentation; Sensitivity and Specificity; subcortical gray matter; Subtraction Technique; Young Adult; R2; segmentation; brain iron; quantitative susceptibility mapping; multiple sclerosis; subcortical gray matter
• ISSN: 1053-1807; 1522-2586; 1522-2586
• DOI: 10.1002/jmri.24951

Purpose To investigate subcortical gray matter segmentation using transverse relaxation rate (R2*) and quantitative susceptibility mapping (QSM) and apply it to voxel‐based analysis in multiple sclerosis (MS). Materials and Methods Voxel‐based variation in R2* 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 T1‐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 R2* and QSM was found in MS subjects compared to controls in portions of all four nuclei studied (P < 0.002). For R2*, 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 R2* and QSM in MS subjects in all four nuclei studied with R2*, benefiting the most from localized analysis over whole‐structure measures. J. MAGN. RESON. IMAGING 2015;42:1601–1610.