The Value Of "Swallow Tail" Appearance In The Substantia Nigra Using Susceptibility Weighted Imaging In Diagnosing Parkinson's Disease

Objective: To explore the diagnostic value of the absence of“swallow tail” appearance at 3.0 Tesla susceptibility weighted imaging(SWI)in Parkinson's disease(PD)and analyze the correlation between visualization of nigrosome-1 and clinical data of PD patients.Methods: We enrolled 50 PD patients and 57 sex-and age-matched non-PD patients from the Department of Neurology,the First Affiliated Hospital of Chongqing Medical University from September 2017 to November 2019.Demographic and clinical data of all subjects were collected.All subjects underwent 3.0T SWI.The SWI images of all subjects were evaluated by two clinicians blinded to the clinical data and diagnosis.Then,the sensitivity,specificity,accuracy and predictive values of the absence of “swallow tail” appearance in diagnosing PD were calculated.The correlation between visualization of nigrosome-1 and clinical data was also assessed.Results: Taking the absence of “swallow tail” appearance as theimage diagnostic criteria for PD,45 PD patients were diagnosed correctly.Inter-rater agreement was excellent(k=0.963,P=0.000).The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of discriminating PD patients from non-PD patients with the absence of “swallow tail” appearance were 90.0%,91.2%,90.7%,90.0% and91.2%,respectively.44 PD patients showed clinical asymmetry.MR imaging showed asymmetric nigrosome-1 in 36 PD patients.There was no significant difference between the laterality of nigrosome-1 and clinical laterality(?2=5.756,P=0.056).Bilateral nigrosome-1 of 11 PD patients were totally absent.There was a significant difference in Hamilton Depression Scale score between “total absence group” and “non-total absence group”(U=126.500,P=0.038).There were no significant differences in the course of disease,Unified Parkinson's Disease Rating Scale-? score,modified Hoehn-Yahr stage,Mini Mental State Examination score and Montreal Cognitive Assessment score between two groups(P=0.768,P=0.140,P=0.839,P=0.054,P=0.067).Conclusions: The absence of “swallow tail” appearance at 3.0T SWI has a high accuracy in the diagnosis of PD and the degree of deletion may reflect the degree of depression.It has a certain reference value for the clinical diagnosis of PD and can be used as an imaging biomarker for the diagnosis of PD.