RESUMEN
Objective:To investigate the distribution of iron deposition in the substantia nigral (SN) subregions on quantitative susceptibility mapping (QSM) and the change of swallow tail sign (STS) in patients with relapsing-remitting multiple sclerosis (RRMS) of different disease stages.Methods:The clinical and imaging data of 53 patients with RRMS (case group) diagnosed at the First Hospital of Chongqing Medical University from November 2019 to December 2021 were retrospectively analyzed. The case group was divided into 0-5 years subgroup, 6-10 years subgroup, and >10 years subgroup according to the disease duration; another 37 age-and gender-matched healthy volunteers were recruited as the control group during the same period. All subjects underwent MRI and QSM reconstruction. First, the SN was divided into four subregions: rostral anterior-SN (aSNr), rostral posterior-SN (pSNr), caudal anterior-SN (aSNc), and caudal posterior-SN (pSNc) on the QSM, and the quantitative susceptibility value (QSV) of each subregion was measured, and then the STS of the SN was observed and scored on the susceptibility weighted imaging (SWI) generated by post-processing. ANOVA was used to compare the differences in the QSV of each subregion of SN among the groups, and the probability of abnormal STS was compared using the χ 2 test. Spearman′s test was used to analyze the correlation between the QSV of each subregion of SN and the STS score. Results:The differences in QSV of aSNr, pSNr, aSNc, and pSNc were statistically significant among the 0-5 years subgroup, 6-10 years subgroup,>10 years subgroup of RRMS patients and the control group ( P<0.05). The QSV of aSNr, pSNr, and aSNc in 0-5 years subgroup was higher than those in the control group ( P was 0.039, 0.008, 0.039, respectively). The QSV of aSNr, aSNc, and pSNc in the 6-10 years subgroup were higher than those in the 0-5 years subgroup ( P was <0.001, 0.020, 0.015, respectively). The QSV of the aSNc, pSNc in >10 years subgroup were lower than those in the 6-10 years subgroup ( P=0.037, 0.006). The QSV of aSNr, pSNr in >10 years subgroup were higher than those in the control group ( P was <0.001, 0.001). There were 7 cases of abnormal STS in the 0-5 years subgroup, 11 cases in the 6-10 years subgroup, 12 cases in >10 years subgroup, and 9 cases in the control subgroup, and there was a statistically significant difference in the probability of abnormal STS among the subgroups of the RRMS patients and the control subgroup (χ 2=16.20, P=0.011). Both the scores of STS in the 6-10 years subgroup and >10 years group were positively correlated with the QSV in pSNc ( r s=0.65, P=0.006; r s=0.48, P=0.045). Conclusions:In RRMS patients, SN iron deposition is concentrated on aSNr, pSNr, and aSNc in the 0-5 years subgroup and on aSNr, aSNc and pSNc in the 6-10 years subgroup. The QSVs of all SN subregions have a downward trend in >10 years subgroup compared with that in the 6-10 years subgroup. Both the QSVs of the pSNc in the 6-10 years group and >10 years group are positively related to STS scores. These help explore the potential progression pattern of SN iron deposition in RRMS patients and the cause of abnormal STS in RRMS patients.
RESUMEN
Objective:To explore the method of establishing a modified demyelination and myelination regeneration model induced by dicyclohexanone oxalyl dihydrazone (CPZ) in mice with multiple sclerosis (MS), and to analyze the image markers of demyelination and myelination regeneration in mouse MS model.Methods:After the intragastrically administered with sodium carboxymethyl cellulose (CMCNa) for one week, a total of 30 C57BL/6 male mice were randomly divided into the control group ( n=10), the demyelination group ( n=10), and the remyelination group ( n=10). The mice of the control group were immediately performed MR scanning and pathological specimen obtaining; the mice in the demyelination group were administered with intragastrical CPZ-CMCNa once a day for 6 weeks for inducing demyelination, then received MR scanning and specimen obtaining with the same protocols used in control group; the mice in the remyelination group were administered with intragastrical CPZ-CMCNa once a day for six weeks for demyelination, then CPZ was withdrawn and normal diet was given for another four weeks. Then MR scanning and specimen obtaining were performed with the same protocols used in the other two groups. Regions of interest (ROIs) were set at the rostrum of corpus callosum (rCC), the bilateral normal appearing white matters (NAWM) of the rostrum of corpus callosum, and the bilateral cerebral cortex (Cx). The normalized T 2WI (T 2-normalized), fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) values were compared among the three groups by one-way ANOVA. Results:The demyelination and remyelination mice model of MS were successfully established. The T 2-normalized values of rCC in control group, demyelination group and remyelination group were 0.47±0.03, 0.72±0.04, 0.54±0.04, respectively, with statistically significant difference found ( F=90.511, P<0.05). Post-hoc multiple comparisons showed significant differences among those groups ( P<0.05). There was no significant difference of T 2-normalized value in NAWM and Cx among the three groups ( P>0.05). Moreover, there were significant differences in the FA values (0.36±0.04, 0.29±0.03, and 0.32±0.05), the MD values [(0.572±0.015), (0.598±0.034), and (0.626±0.043)×10 -3 mm 2/s], the AD values [(0.79±0.04), (0.77±0.06), and (0.83±0.04)×10 -3 mm 2/s], and the RD values [(0.46±0.02), (0.51±0.03), and (0.53±0.05)×10 -3 mm 2/s] of rCC of the control group, the demyelination group, and the remyelination group (all P<0.05). Significant difference was found in FA values between the demyelination group and the control group ( P<0.05), and in MD values between the remyelination group and the control group ( P<0.05), as well as in AD values between the remyelination group and the demyelination group ( P<0.05). There were also significant differences in RD values between the remyelination group and the control group, and the demyelination group and the control group (all P<0.05). However, no significant difference was found in all diffusion tensor imaging (DTI) metrics of NAWM and Cx among the three groups (all P>0.05). The LFB-eosin staining showed that the myelin sheath of rCC was lost in the demyelination group, and the rCC was partially regenerated and repaired in the remyelination group. Conclusion:The modified CPZ-CMCNa model can selectively induce demyelination and remyelination of rCC, and the changes of demyelination and remyelination of rCC in the modified CPZ-CMCNa model can be quantitatively detected by T 2WI combined with DTI, which might provide related theoretical basis for the study on dynamic changes of MS lesions.