title: The radial diffusivity and magnetization transfer pool size ratio are sensitive markers for demyelination in a rat model of type III multiple sclerosis (MS) lesions.
abstract: Determining biophysical sensitivity and specificity of quantitative magnetic resonance imaging is essential to develop effective imaging metrics of neurodegeneration. Among these metrics, apparent pool size ratio (PSR) from quantitative magnetization transfer (qMT) imaging and radial diffusivity (RD) from diffusion tensor imaging (DTI) are both known to relate to histological measure of myelin density and integrity. However their relative sensitivities towards quantitative myelin detection are unknown. In this study, we correlated high-resolution quantitative magnetic resonance imaging measures of subvoxel tissue structures with corresponding quantitative myelin histology in a lipopolysaccharide (LPS) mediated animal model of MS. Specifically, we acquired quantitative magnetization transfer (qMT) and diffusion tensor imaging (DTI) metrics (on the same tissue sample) in an animal model system of type III oligodendrogliopathy which lacked prominent lymphocytic infiltration, a system that had not been previously examined with quantitative MRI. We find that the qMT measured apparent pool size ratio (PSR) showed the strongest correlation with a histological measure of myelin content. DTI measured RD showed the next strongest correlation, and other DTI and relaxation parameters (such as the longitudinal relaxation rate (R1f) or fractional anisotropy (FA)) showed considerably weaker correlations with myelin content.
authors.affiliation: Institute of Imaging Science, Vanderbilt University, Nashville, TN 37232-2310, USA.
authors.forename: Vaibhav A
authors.initials: VA
authors.lastname: Janve
authors.forename: Zhongliang
authors.initials: Z
authors.lastname: Zu
authors.forename: Song-Yi
authors.initials: SY
authors.lastname: Yao
authors.forename: Ke
authors.initials: K
authors.lastname: Li
authors.forename: Fang Lin
authors.initials: FL
authors.lastname: Zhang
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Wilson
authors.forename: Xiawei
authors.initials: X
authors.lastname: Ou
authors.forename: Mark D
authors.initials: MD
authors.lastname: Does
authors.forename: Sriram
authors.initials: S
authors.lastname: Subramaniam
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Gochberg
mesh_terms: D000818:Animals; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D003711:Demyelinating Diseases / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D004195:Disease Models, Animal; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D009103:Multiple Sclerosis / Q000473:pathology*; D051381:Rats