The Value Of Neuromelanin-sensitive Magnetic Resonance Imaging In The Diagnosis Of Parkinson's Diseas

Objective:To investigate the application value of neuromelanin-sensitive magnetic resonance imaging(NM-MRI)in the diagnosis of Parkinson’s Disease(PD)and differentiation of motor subtypes by comparing the size of high signal area in substantia nigra pars compacta(SNc)between PD patients and controls,and by comparing the size of high signal area in SNc among different motor subtypes of PD.Methods:Sixty-five PD patients(PD group)and fifty-five patients without neurodegenerative diseases(normal control group)were prospectively collected from May2019 to January 2020 in our hospital,and scanned by NM-MRI.Two researchers measured the area of SNc high signal area and the ratio of SNc area to midbrain area on NM-MRI images.Mann-Whitney U test was used to compare the differences of SNc area and the ratio of SNc area to mesencephalic area between PD group and control group.The receiver operating characteristic(ROC)curves of SNc area and the ratio of SNc area to midbrain area in the same layer were plotted respectively,and the area under the curve(AUC)was calculated to find the best cut-off value for the diagnosis of PD,and analyzing the correlation between the measured values on NM-MR images and the course and severity of PD.In addition to,the PD patients were divided into the postural instability gait difficulty(PIGD)group(n=13)and the tremor dominant(TD)group(n=20).Mann-Whitney U test was used to compare the differences of SNc area and the ratio of SNc area to midbrain area in the two motor subtypes.Results:The SNc area and the ratio of SNc area to midbrain area were markedly decreased in the PD group compared with the normal control group(P<0.05).The AUC measured by the SNc area was 0.958(95%CI:0.923～0.992),the best cut-off value of the indicator was 27.11mm~2,the sensitivity was 90.9%and specificity was 92.3%.The AUC measured by the ratio of SNc area to midbrain area was 0.919(95%CI:0.872～0.967),the best cut-off value of the indicator was 0.047,the sensitivity was 89.1%and specificity was81.5%.The SNc area and the ratio of SNc area to midbrain area were remarkably correlated with disease duration,UPDRS-III score and H-Y stage,respectively.However,there was no significant difference of the SNc area and the ratio of SNc area to midbrain area between TD group and PIGD group(P>0.05).Conclusion:This study shows that NM-MRI can distinguish Parkinson’s disease patients and normal controls,which helps to better understand the pathological changes of Parkinson’s disease.And,the decrease of neuromelanin represented by the measured value on NM-MRI image in PD patients was significantly aggravated with disease duration and severity,indicates that the NM-MRI has a good potential in monitoring the disease progression in PD,and can provide a basis for clinical precise treatment.However,further research and analysis about NM-MRI are needed to distinguish the motor subtypes of PD.