Quantitative analysis of demyelination mouse model using signal intensity ratio and diffusion tensor imaging at 7.0 Tesla MRI

Abstract

Objective To assess the value of combined signal intensity ratio (SIR) and diffusion tensor imaging (DTI) measured at 7.0 T MRI in quantitative detection and analysis of gray and white matter demyelination in the modified cuprizone (CPZ)-induced mouse model of multiple sclerosis (MS). Methods A total of 20 mice were randomly divided into experimental group (n=10) and control group (n=10), and were intragastrically administrated with CPZ-carboxymethyl cellulose sodium (CMCNa) suspension and 0.5% CMCNa solution, respectively. In 6 weeks after administration, the mice of both groups were given T1WI and T2WI scanning on 7.0 T MRI, and the SIR value was calculated by linear registration of T1WI and T2WI. Besides, DTI scanning was also conducted in both groups to obtain the diffusion parameters such as fractional anisotropy (FA) and mean diffusivity (MD). Moreover, pathological observation was performed on cerebral tissues after Luxol fast blue staining for mean grayscale value (MGSV). Then corpus callosum (CC), bilateral cerebral cortex (CTX), bilateral thalamus (THA), and bilateral hippocampus (HIP) were selected as the regions of interest (ROI). SIR, FA, MD and MGSV of above regions were subsequently compared between the experimental and control groups. Finally, pairwise correlation analysis and linear fitting were carried out on the MRI metrics and pathological parameters. Results As compared with the control group, the CC region in the experimental group showed significant demyelinating changes, with lower SIR and FA values and higher MGSV (P 0.05). However, in terms of other cerebral regions, there were no significant differences between the 2 groups in SIR, FA, MD and MGSV values (P>0.05). Correlation analysis suggested that both SIR and FA values were negatively correlated with MGSV, with |rSIR|>|rFA|. Conclusion SIR combined with DTI can quantitatively evaluate the demyelination changes of white matter in MS model.

Keywords

• magnetic resonance imaging
• signal intensity ratio
• diffusion tensor imaging
• multiple sclerosis
• demyelination
• cuprizone model