- 學位論文
擴散磁振造影定量廣東住血線蟲感染兔腦 之病理變化
Characterizing Pathological Changes of Rabbit Brain Infected with Angiostrongylus Cantonensis Using Diffusion MRI
摘要
廣東住血線蟲(Angiostrongylus cantonensis, A .Cantonensis)在台灣為造成嗜酸性白血球腦膜炎及腦炎之主要致病原因，近年來，感染地區已由東南亞與太平洋地區擴展至全球各地。若誤食入感染性第三期廣東住血線蟲幼蟲，常造成急性嗜酸性白血球腦膜腦炎及腦炎，並伴隨其它腦脊髓等中樞神經障礙。廣東住血線蟲症其臨床症狀不具特異性且確認診斷困難，又需要做侵入性腰椎穿刺。因此我們使用磁振擴散張量造影(Diffusion tensor imaging, DTI)及磁振造影來找出兔腦感染廣東住血線蟲之變化，並與病理結果相互驗證。本研究使用5隻紐西蘭大白兔，於未感染前及在感染700隻廣東住血線蟲後，進行6周之每周腦部擴散張量磁振造影及傳統磁振造影掃描。再以 Matlab, Mathematica, DSI studio及Image J進行影像分析，觀察兔子腦部的腦室大小，腦脊髓液訊號變化，嗅球(Olfactory bulb)、胼胝體(Corpus callosum) 、海馬迴(Hippocampus) 、大腦皮質(Cortex)之擴散非等張性(Fractional anisotropy, FA) 、平均擴散指標(Mean diffusivity, MD) 、徑向擴散指標(Radial diffusivity, RD)及軸向擴散指標(Axial diffusivity, AD)的變化。 本研究結果發現，腦室大小，腦脊髓液訊號，海馬迴之擴散指標會隨感染時間增加有明顯的改變，可能是因蟲體破壞海馬迴腦組織，造成腦病變（如：血栓、發炎、出血）以及水腦。這與病理有類似的結果。故藉由擴散張量磁振造影觀察廣東住血線蟲在兔腦感染的現象，以及對腦部侵害的病程，未來希望建立一個嗜酸性白血球腦膜炎及腦炎治療或控制的追蹤的平台，提供臨床與基礎醫學研究。
並列摘要
Angiostrongylus cantonensis (A. Cantonensis) is the most common cause of eosinophilic meningitis or eosinophilic meningoencephalitis in Taiwan, Southeast Asia and the Pacific Basin. Humans may become infected after ingestion of the infected worms in raw snails and contaminated vegetables. The diagnosis of eosinophilic meningitis result from A. Cantonensis is difficult and invasive such as lumber puncture. Therefore, the purpose of this study was to determine the longitudinal effects of rabbit brain infected with 700 larvae of A. cantonensis by advanced MRI techniques such as diffusion tensor imaging (DTI), and the results were verified by histopathological study. Each of five New Zealand white rabbits was infected by the 700 3rd-stage larvae of A. Cantonensis. MR scans were performed before and each week after infection of A. Cantonensis by using a 1.5T system. T2WI, FLAIR, R2 mapping and DTI was performed. The ventricle size, signal intensity (SI) of CSF, the fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity (AD) values of the olfactory bulb, corpus callosum, hippocampus and cortex were collection. The data were analyzed by Mathematica, Matlab, Image J and DSI studio. Our MRI results showed the ventricle size, signal intensity of CSF and the FA, MD, RD values of the hippocampus of each infected rabbit gradually change over time. These image findings were correlation with histopathological study. It may due to the hydrocephalus, CSF hemorrhage and inflammatory process over the hippocampus in the infected rabbit brain. Therefore, MRI was suggested to be a non-invasive technique in detecting eosinophilic meningitis resulted from A. Cantonensis. In the future, the non-invasive MRI platform developed in rabbits can be extended for diagnosis and treatment in eosinophilic meningitis or eosinophilic meningoencephalitis.