Department of Radiologic Technology, Carinthia University of Applied Sciences, Klagenfurt, Austria.
Institute of Radiology, Villach General Hospital, Villach, Austria.
J Neuroimaging. 2019 Jan;29(1):65-69. doi: 10.1111/jon.12576. Epub 2018 Nov 8.
Susceptibility weighted imaging (SWI) plays a role in the differential diagnosis of Parkinson's disease, but lacks widespread acceptance in clinical routine. In a descriptive pilot study, we assessed hypointense microstructures of the normal substantia nigra pars compacta at ultrahigh-field strength for interpretation of the "swallow tail sign."
Magnetic resonance imaging at 7 Tesla was performed in five postmortem samples obtained from subjects not affected by Parkinson's disease. Susceptibility weighted images, including minimum intensity projections, were created followed by consensus assessment for microvascular confound. Histological workup in this case-control study included iron and myelin staining. Seven Tesla SWI images from the reference cohort of nine living subjects, all of which showed a positive "swallow tail sign" in their midbrains, were assessed visually.
All specimens showed microvessels running through the dorsal pars compacta and along the caudolateral circumference of the red nucleus. Hypointense imaging patterns in the medial part of the "swallow tail" were due to susceptibility effects of iron deposits and microvessels. In eight out of nine control subjects, one or more microvessels were detected medial to the dorsolateral nigral hyperintensity or at least unilaterally in the medial part of the "swallow tail." One microvessel crossing nigrosome 1 was found in two in-vivo cases.
Both iron deposits and microvessels contribute to the hyposignal surrounding nigrosome 1 in susceptibility weighted imaging of normal aged midbrains at ultrahigh-field strength. When assessing the substantia nigra for the presence or absence of the "swallow tail sign," intrinsic vessels may be a sporadic confounder.
磁敏感加权成像（SWI）在帕金森病的鉴别诊断中具有一定作用，但尚未在临床常规中广泛应用。在一项描述性的初步研究中，我们评估了超高场强下正常黑质致密部的低信号微观结构，以解释“燕尾征”。
对来自未患帕金森病的五例尸检样本进行 7 特斯拉磁共振成像。创建磁敏感加权图像，包括最小强度投影，并进行微血管混杂的共识评估。本病例对照研究的组织学工作包括铁和髓鞘染色。对来自 9 例活体参考队列的 7 特斯拉 SWI 图像进行视觉评估，所有这些图像在中脑均显示出阳性“燕尾征”。
所有标本均显示血管穿过背侧致密部并沿着红核的外侧尾侧走行。“燕尾”内侧的低信号成像模式归因于铁沉积和微血管的磁敏感效应。在 9 例对照受试者中，8 例在黑质背外侧高信号的内侧或“燕尾”的内侧单侧发现了一条或多条微血管。在 2 例活体病例中发现了一条穿过黑质 1 区的微血管。
在超高场强的正常老年中脑的磁敏感加权成像中，铁沉积和微血管均导致黑质 1 周围的低信号。在评估“燕尾征”的存在与否时，固有血管可能是一个偶发混杂因素。
