Susceptibility source separation from gradient echo data using magnitude decay modeling. Issue 5 (6th June 2022)

• Record Type: Journal Article
• Authors: Dimov, Alexey V.; Nguyen, Thanh D.; Gillen, Kelly M.; Marcille, Melanie; Spincemaille, Pascal; Pitt, David; Gauthier, Susan A.; Wang, Yi
• Is Part Of: Journal of neuroimaging. Volume 32:Issue 5(2022)
• Page Start: 852
• Page End: 859
• Publication Date: 2022-06-06
• Subjects: iron quantification -- myelin quantification -- quantitative susceptibility mapping -- susceptibility source separation; Diagnostic imaging -- Periodicals; Nervous system -- Diseases -- Diagnosis -- Periodicals; Imagerie pour le diagnostic -- Périodiques; Système nerveux -- Maladies -- Diagnostic -- Périodiques; Imagerie médicale; Neuroimagerie; Neurologie; Système nerveux; Périodique électronique (Descripteur de forme); Ressource Internet (Descripteur de forme); 616.804754
• DOI: 10.1111/jon.13014
• Languages: English
• ISSNs: 1051-2284

Abstract

Abstract: Background and Purpose: The objective is to demonstrate feasibility of separating magnetic sources in quantitative susceptibility mapping (QSM) by incorporating magnitude decay rates R 2 ∗ $R_2^{\rm{*}}$ in gradient echo (GRE) MRI. Methods: Magnetic susceptibility source separation was developed using R 2 ∗ $R_2^{\rm{*}}$ and compared with a prior method using R 2 ′ = R 2 ∗ − R 2 ${R^{\prime}_2} = R_2^* - {R_2}$ that required an additional sequence to measure the transverse relaxation rate R 2 . Both susceptibility separation methods were compared in multiple sclerosis (MS) patients ( n = 17). Susceptibility values of negative sources estimated with R 2 ∗ $R_2^{\rm{*}}$ ‐based source separation in a set of enhancing MS lesions ( n = 44) were correlated against longitudinal myelin water fraction (MWF) changes. Results: In in vivo data, linear regression of the estimated χ + ${\chi}^{+}$ and χ − ${\chi}^{-}$ susceptibility values between the R 2 ∗ $R_2^*$ ‐ and the R 2 ′ ${R^{\prime}_2}$ ‐based separation methods performed across 182 segmented lesions revealed correlation coefficient r = .96 and slope close .99. Correlation analysis in enhancing lesions revealed a significant positive association between the χ − ${\chi}^{-}$ increase at 1‐year post‐onset relative to 0 year and the MWF increase at 1 year relative to 0 year ( β = ‐0.144, 95% confidence interval: [–0.199, –0.1], p = .0008) and good agreement between R 2 ′ ${R^{\prime}_2}$ and R 2 ∗ $R_2^*$ methods ( r = .79, slope = .95). Conclusions: Separation of magnetic sources based solely on GRE complex data is feasible by combining magnitude decay rate modeling and phase‐based QSM and χ − ${\chi}^{-}$ change may serve as a biomarker for myelin recovery or damage in acute MS lesions.