| Background and purpose: Neuromyelitis optica spectrum disorder(NMOSD)is an autoimmune disease that mainly affects the optic nerve and spinal cord,most patients have antibodies against aquaporin-4 in their serum.If undiagnosed and untreated,severe immune-mediated attacks on themself cause corresponding symptoms in the optic nerve and spinal cord,it can lead to blindness or paralysis.Optic neuritis is often the earliest manifestation of NMOSD.How to diagnose and evaluate the disease course early has always been the focus of clinicians’ attention.Conventional magnetic resonance imaging can not be used for quantitative evaluation and has some limitations.Therefore,looking for imaging markers in patients with NMOSD is still the research direction of domestic and foreign scholar.With the progress of magnetic resonance technology,more and more advanced magnetic resonance technology has been applied to clinical research to provide a basis for exploring the pathophysiology of diseases.DTI and DKI have broad prospects in the study of white matter fibers,and have great potential in the diagnosis of NMOSD and disease assessment.The purpose of this study is to use DTI and DKI technology to quantitatively detect the changes of optic nerve and optic radiation in patients with NMOSD,and analyze the correlation between imaging quantitative indicators and clinical data,and find imaging biomarkers that can evaluate the condition of patients,so as to effectively guide the formulation of clinical treatment plan and improve the prognosis of patients.Materials and methods: In this study,40 patients with NMOSD admitted to our hospital from June 2019 to December 2020 with unilateral optic neuritis,including13 males and 27 females,aged 21~60 years old,with an average age of 38.70±11.10 years old.At the same time,40 gender and age matched normal control group were collected,including 13 males and 27 females,aged 23~55 years old,with an average age of 38.07±9.72 years old.All subjects were scanned by GE 3.0T magnetic resonance,8-channel head/neck combination coil,conventional head plain scanning,DTI and DKI scanning.The scanning location lines were consistent,parallel to the optic nerve level,and the scanning range covered the whole brain.The image was transferred to ADW4.6 workstation for post-processing,and the region of interest was drawn on the anatomical images of optic nerve and optic radiation,three ROIs were drawn on each side of optic nerve and optic radiation,and the average value was taken as the final result.Patients were pairwise compared between the affected side group,the contralateral side group and the normal control group,the contralateral side and the normal control group,Multiple corrections were made for the pairwise comparison results,P<0.0167 indicated that the difference was statistically significant.Before scanning,professional clinicians recorded the patient’s course of disease and frequency of onset,expanded disability scale score,visual acuity,retinal nerve fiber layer thickness,and conducted correlation analysis between clinical data and image indicators,P<0.05 indicated statistically significant difference.The ICC was used to evaluate the consistency between the two observers,and the ICC>0.75 considered the consistency to be good.Results: 1.The FA values of the affected and contralateral optic nerves in NMOSD patients(mean ± standard deviation,affected side: 0.381±0.093,contralateral side: 0.390±0.090)were lower than those in the control group(0.516±0.050);MD value(affected side: 1.280±0.309;contralateral side: 1.158±0.271)was higher than that of control group(0.992±0.164);AD value(affected side: 1.761±0.386;contralateral side: 1.660±0.292)was higher than that of control group(1.505±0.219).RD value(affected side: 1.056±0.376,contralateral side: 0.905±0.308)was higher than that of control group(0.721±0.201).The MK value(affected side: 0.653±0.163,contralateral side: 0.711±0.153)was lower than that of the control group(0.807±0.076).AK value(affected side: 0.518±0.103;contralateral side: 0.530±0.091)was lower than that of control group(0.591±0.081).RK value(affected side: 0.799±0.278,contralateral side: 0.838±0.205)was lower than that of control group(0.963±0.202),all P<0.0167.There was no statistical significance in the values of each parameter between the affected side optic nerve and the contralateral side optic nerve,all P >0.0167.2.The FA values of affected side radiation and contralateral side radiation in NMOSD patients(mean±standard deviation,affected side: 0.502±0.053,contralateral side: 0.509±0.045)were significantly lower than those in the control group(0.544±0.030);RD value(affected side:0.525±0.053,contralateral side: 0.523±0.044)was higher than that of control group(0.497±0.031);The MK value(affected side: 0.889±0.041,contralateral side: 0.889±0.027)was lower than that of the control group(0.978±0.124);AKvalue(affected side: 0.746±0.121,contralateral: 0.746±0.120)was lower than that of control group(0.811±0.070);RK value(affected side: 1.247±0.145;contralateral side: 1.259±0.130)was lower than that of control group(1.343±0.170),all P<0.0167.There was no statistical significance in the values of AD and MD between patients with NMOSD and contralateral radiation,and there was no statistical significance in the values of all parameters between patients with contralateral radiation and contralateral radiation,all P >0.0167.3.There were no significant correlation between FA,MD,AD,RD,MK,AK,RK and the course of disease,the frequency of disease and EDSS score(all P >0.05).There was a significant correlation between the visual acuity of the affected side FA value of the affected side optic nerve(r=0.329、P=0.038),but it was not related to the affected side radiation(r=0.022、P=0.890).The affected side RNFL was significant correlated with the affected side optic nerve(r=0.368、P=0.020)but not with optic radiation(0.299,P=0.061).4.Correlation analysis showed that FA was a significant negative correlation with RD,and was significantly positively correlated with MK and RK(r=-0.439、0.440、0.471,P=0.005、0.005、0.002);RD was negatively correlated with RK(r=-0.733、P<0.001)in the affected lateral optic nerve.FA was a significant negative correlation between FA and RD(r=-0.764、P<0.001),and was significantly positively correlated with MK(r=0.663、P<0.001)and RK(r=0.393、P<0.001).RD was negatively correlated with RK(r=-0.475、P=0.002)in the affected lateral optic radiation.Similar correlations were found in contralateral optic nerve and optic radiation.5.ROC curve was used to analyze the diagnostic efficacy between DTI and DKI parameters of affected side optic nerve and optic radiation and normal control group.The FA value of affected side optic nerve had the highest diagnostic efficiency(AUC: 0.912,sensitivity: 92.5%,specificity: 85.0%).MK value was the most effective in the diagnosis of affected side radiation(AUC=0.755,sensitivity=87.5%,specificity = 67.5%).The combined diagnostic efficiency of affected side optic nerve FA value and affected side optic radiation MK value was further improved(AUC=0.941,sensitivity: 92.5%,specificity: 92.5%).Conclusions: 1.The FA and MK values of the optic nerve and optic radiation in NMOSD patients were significantly lower than those in the normal control group,which had important value in the diagnosis and evaluation of NMOSD.2.Patients with NMOSD have occulting injury of optic nerve and optic radiation,and DTI and DKI are helpful to detect occulting injury in patients.3.The FA value of the DTI parameter on the affected side optic nerve was significantly positively correlated with the visual acuity and RNFL of the NMOSD patients,which was of great value in the evaluation of visual impairment of the patients. |
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