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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.
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Multiple sclerosis (MS) is an autoimmune inflammatory demyelinating disease of the central nervous system whose clinical manifestations and diagnostic criteria are non-specific and absence of golden criteria when diagnosing. Magnetic resonance imaging (MRI) can not only observe the focal lesions of demyelination, but also evaluate microstructural damages and iron deposition in the white/gray matter in MS patients by applying various developing sequences. MRIs play an irreplaceable role in revealing pathological evolution, prognosis and monitoring after treatment of MS patients. This paper reviewed the clinical value and application of MRIs for the MS patients in recent years.