Abstract:

Objective  To explore the diagnostic value of substantia nigra "swallow tail sign" in identifying Parkinson's disease (PD) as visualized by quantitative susceptibility mapping (QSM).  Methods  A total of 76 PD patients and 47 sex- and age-matched normal controls were retrospectively enrolled in the study. They were performed MRI examination, including three-dimensional high-resolution MRI (3D-HRMRI), diffusion tensor imaging (DTI), resting-state functional magnetic resonance imaging (rs-fMRI) and enhanced gradient echo T2*-weighted angiography (ESWAN). ESWAN images were used to calculate the map of QSM. A radiologist blinded to the clinical results read the images and determined the existence of "swallow tail sign" in the dorsolateral part of substantia nigra pars compacta. Then the sensitivity, specificity and accuracy of PD diagnosis according to the disappearing of "swallow tail sign" was calculated.  Results  With high contrast of magnetic susceptibility, QSM can display substantia nigra clearly, so as to evaluate the existence or disappering of "swallow tail sign". Among 76 PD patients, 73 (96.05%) showed the absence of unilateral or bilateral "swallow tail sign". Among 47 normal subjects, 28 (59.57%) showed the absence of unilateral or bilateral "swallow tail sign". There was significant difference between 2 groups (χ² = 26.311, P = 0.000). The sensitivity, specificity and accuracy of discriminating PD patients from normal subjects with "swallow tail sign" were 96.05%, 40.43% and 74.80% respectively.  Conclusions  Although "swallow tail sign" can be detected sensitively by QSM in PD patients, the specificity of discrimination between PD patients and normal controls is relatively low. The utility of high-resolution MRI and precise quantitative analysis may be helpful to improve its diagnostic value in PD patients.

Key words: Parkinson disease, Substantia nigra, Magnetic resonance imaging

摘要：

目的 探讨定量磁敏感图（QSM）显示的黑质“燕尾征”消失征象对帕金森病的诊断价值。方法 共76 例帕金森病患者和47 例性别、年龄相匹配的正常对照者均行头部MRI 检查，包括三维高分辨力MRI、扩散张量成像、静息态fMRI和多回波采集的增强T2*加权血管成像（ESWAN），ESWAN 图像经处理后获得QSM 图，计算帕金森病患者和正常对照者黑质致密部背外侧区“燕尾征”出现率和消失率，并计算“燕尾征”消失征象诊断帕金森病的灵敏度、特异度和准确度。结果 QSM 图具有极高的磁化率对比，76 例帕金森病患者中73 例（96.05%）出现单侧或双侧“ 燕尾征”消失，47 例正常对照者中28 例（59.57%）出现单侧或双侧“燕尾征”消失，组间差异有统计学意义（χ² = 26.311，P = 0.000）。“燕尾征”消失征象诊断帕金森病的灵敏度为96.05%、特异度为40.43%、准确度为74.80%。结论 QSM 图可以准确识别帕金森病患者黑质致密部背外侧区“燕尾征”消失征象，但特异性较低，采用高分辨力MRI和精确定量分析方法有助于提高该项技术在帕金森病诊断中的应用价值。

关键词: 帕金森病, 黑质, 磁共振成像