Combined Quantitative Susceptibility Mapping And Proton Exchange Rate Imaging Technique To Study The Role Of Iron Deposition And Oxidative Stress In The Pathogenesis Of MS In Vivo

Part Ⅰ: Quantitative magnetic susceptibility imaging studies of multiple sclerosis and optic neuromyelitis lineage diseaseObjective: To study the value of quantitative susceptibility mapping in the differential diagnosis of multiple sclerosis and neuromyelitis optica spectrum disorders demyelinating diseases.Materials and methods: 31 cases of MS and 17 cases of NMOSD patients with intracranial lesions in our hospital from December 2017 to May 2019 were collected in this study.All patients underwent conventional MRI(Axi FSE T2 W,T2FLAIR)and three-dimensional multi-echo GRE sequence.QSM images are reconstructed from post processing of GRE raw data.T2 hyperintensities were assumed to be MS or NMOSD lesions.Random blind reading was used to analyze the signal,morphology and central vein signs of all lesions on the QSM,and outline the ROI to quantitatively measure the magnetic sensitivity of the lesion.Differences between groups were compared using chi-square test and two independent samples t test.And evaluate the sensitivity and specificity of each sign for identifying MS and NMOSD lesionsResults: In this study,31 MS and 17 NMOSD patients detected 488 MS lesions and 150 NMOSD lesions,respectively.Among the 488 MS lesions,411(84.2%)MS lesions showed hyperintensities on the QSM,and 77(15.8%)MS lesions showed isointensities.Among MS lesions with hyperintensities on QSM,201(48.9%,201/411)showed relatively uniform nodular hyperintensities,and 210(51.1%,210/411)showed ring hyperintensities.And at least one lesion in all MS patients showed nodular or circular hyperintensities on QSM.156(32%)MS lesions had positive CVS,and 77.4%(24/31)of MS patients had CVS visible in at least one lesion.Of the 150 NMOSD lesions,only 3(2%)NMOSD lesions showed hyperintensities on the QSM,all of which were nodular hyperintensities,from 2(11.8%,2/17)NMOSD patients.All lesions in the NMOSD group were negative for CVS.Compared with NMOSD lesions,MS lesions had significantly increased QSM hyperintensities performance(84.2% vs 2%,p <0.001)and significantly increased CVS-positive lesions(32% vs 0,p <0.001).The sensitivity and specificity of MS and NMOSD identified by ≥1 QSM high-signal lesion were 100%(95% CI: 86.3%-100%)and 88.2%(95% CI: 62.3%-97.9%),respectively.The sensitivity and specificity of identifying MS and NMOSD with CVS on QSM using ≥1 lesion were 77.4%(95% CI: 58.5%-89.7%)and 100%(95% CI: 77.1%-100%),respectively.The magnetic sensitivity value of MS lesions was significantly higher than that of NMOSD lesions(24.65 ± 16.75 ppb vs 3.07 ± 5.68 ppb,p <0.001).The magnetic sensitivity value of MS lesions with positive CVS sign was significantly higher than that of MS lesions with negative CVS(30.4 ± 17.3 ppb vs 22.0 ± 15.9ppb,p= 0.004).Conclusion: QSM hyperintensities and central venous signs are MS-specific imaging signs.QSM imaging has high accuracy in distinguishing MS and NMOSDPart Ⅱ : Combined application of quantitative magnetic susceptibility imaging and proton exchange rate imaging to explore the correlation between iron and oxidative stress in MS lesions Objective: To study the relationship between iron content and oxidative stress level in MS lesions by combining quantitative magnetic susceptibility imaging and proton exchange rate imaging.Materials and Methods: We included 16 patients with MS confirmed clinically from August 2018 to May 2019 in our hospital.All patients underwent T2 WI,CESTsequence at different saturation power and three-dimensional multi-echo GRE sequence imaging.The kex mapping and QSM images were reconstructed from the original CEST and GRE data respectively;T2 hyperintensities were assumed to be MS lesion,and two experienced radiologists performed a separate random blind reading of the image and observed The signal performance of all lesions on the QSM and kex mapping.If there is a difference in results,consult another experienced neuroradiologist to reach an agreement.Draw the ROI manually on the QSM map and kex mapping to obtain the susceptibility and Kex values of the lesion and NAWM,respectively.The difference in kex values between lesions and NAWM and between QSM hyperintensities lesions and isointensities lesions was compared by two independent sample t-tests.Spearman correlation analysis was performed on the QSM and kex values of MS lesions.p <0.05 means the difference is statistically significant.Results: A total of 153 MS lesions were detected in 16 MS patients.On kex MRI,Kex increased in 136(88.9%)lesions,and Kex did not increase in 17(11.1%)lesions.Compared with NAWM,the average kex value of MS lesions was significantly increased(931.2 ± 136.1 s-1 vs 742.3 ± 57.2 s-1,p <0.001).On the QSM,130(85%)lesions showed hyperintensities,and 23(15%)lesions showed isointensities.The average kex value of MS lesions with high signal of QSM was significantly higher than that of lesions with equal signal on QSM(949.6 ± 130.7 vs 829.9 ± 111.1,p <0.001).Combined with QSM and kex mapping diagrams,MS lesions present three modes: 1)QSM hyperintensities + kex increase,this mode is the most common,accounting for 73.9%(113/153)of total lesions;2)QSM hyperintensities + kex There was no obvious change,accounting for 11.1%(17/153);3)QSM isointensities + kex increased,accounting for 15%(23/153).Spearman correlation analysis showed that there was a correlation between the lesion susceptibility value and the proton exchange rate kex value,r = 0.514,p <0.001.Conclusion: There is a general phenomenon of increased oxidative stress in MS lesions;and there is a positive correlation between the level of oxidative stress and the magnetic sensitivity of the lesion.