近年來聚焦式超音波搭配微氣泡已被證實可局部性且暫時性的開啟血腦屏障，以增加腦部病變的治療效率，但此技術若施打的聲壓過高可能造成局部腦出血、短暫缺血性中風等急性病症發生，以目前造影技術而言，磁振造影缺乏時間解析度、超音波對比增強影像則受微氣泡本身的限制而不能連續監控其變化，所以至今仍缺乏一種可即時且連續監控血腦屏障開啟後腦區動態變化的造影技術以評估聚焦式超音波是否造成潛在的傷害。本研究提出一基於超音波內源性對比之時間強度曲線(time-intensity curve, TIC)技術來即時地監控大鼠模型中聚焦式超音波血腦屏障開啟區域的動態變化。由於腦血液的超音波逆散射能力高於周遭的腦組織，因此我們可利用血液本身的超音波逆散射訊號強度做為腦部變化監控的指標。本研究監控兩個開啟血腦屏障的典型：不出血與伴隨微出血。開啟血腦屏障後伴隨微出血情時，實驗結果顯示聚焦式超音波施打區(左腦)的TIC在血腦屏障開啟後立即上升並於10分鐘後開始下降，對側腦(右腦)的TIC持續下降且降幅可達15 %，左腦訊號強度的表現主要來自於出血反應，並可能含有部分的缺血反應，右腦血管則受血液流量自動調節(flow auto-regulation)而收縮迫使血液往缺血較嚴重的左腦補償；在開啟血腦屏障後未出血時，左腦的TIC持續下降且降幅可達25 %、右腦TIC的結果與出血TIC的結果一致，其可能的原因為此時左腦單純受聚焦式超音波的機械力刺激收縮而產生缺血現象，使血液量減少進而使TIC呈現下降的趨勢，右腦血液量變化的成因則與上述微出血的右腦相同。本研究證實超音波內源性時間強度曲線可確實反映腦血液量的變化幅度，且實驗結果亦得到了光聲造影對血液高對比度結果的佐證。本研究所提出的監控方法未來有潛力應用於監控腦血液在不同治療階段的變化程度、腦部受損程度的輔助診斷、改進聚焦式超音波的治療參數等方面，最終目的為提供聚焦式超音波治療更安全的治療參數。

Recently, focused ultrasound (FUS) has been proved to be able to open the blood-brain barrier (BBB) locally and temporarily, which can increase the performance of the treatment for brain diseases. However, rapid and acute symptoms like hemorrhage and ischemia stroke may occur if the applied acoustic pressure is too high. Currently, the reported imaging modalities for monitoring BBB opening are magnetic resonance imaging (MRI) and contrast enhanced ultrasound imaging (CEUI), but MRI is lack of temporal resolution and CEUI can not provide continuous monitoring due to the survival time of the microbubbles. Therefore, an imaging technique that can provide both dynamic and continuous monitoring of the transient response of the brain after FUS-induced BBB opening is desirable. In this study, we propose an intrinsic contrast based ultrasound time intensity curve (TIC) technique for real-time monitoring the dynamic response of FUS-induced BBB opening on a rat model. Because the ultrasound backscattering coefficient of the cerebral blood is higher than that of the peripheral brain tissues, the intensity of backscatter signal can be used be the indicator to analyze the variation of the cerebral blood flow and hemorrhage during FUS-induced BBB opening. Two considerable cases of BBB opening – with and without hemorrhage – was performed by 1-MHz FUS and monitored by the proposed TIC technique. In the case with microhemorrhage, the TIC of the sonicated area (left brain) rose immediately after the BBB opening and then gradually declined after 10 minutes. The TIC of controlled contralateral (right) brain gradually dropped to 85 % of the baseline at the end of the monitoring. The response of the left brain was dominated by the brain hemorrhage and was suspiciously mingled with the effect of ischemia. The TIC of the right brain showed a high performance of flow auto-regulation which is the forced vasoconstriction of the right brain compensating blood to the left brain. In the case without hemorrhage, the TIC of the left brain gradually dropped to 75 % of the baseline at the end of the monitoring; the right one was in accordance with the result of the condition with microhemorrhage. In this case, FUS induced vasoconstriction and thus caused reduction of blood volume in the left brain, and this lead to the compensation of the blood from the right brain induced by flow auto-regulation. In this study, the intrinsic contrast based ultrasound TIC was proved to be able to quantitatively reflect the variation of the cerebral blood flow, and the results were also verified by using photoacoustic imaging technique which is sensitive to blood content. The proposed method has potential to be applied to monitoring cerebral blood flow changes at different stages of treatment the degree of brain damage, improve parameters of focused ultrasound. The ultimate goal is to provide safer treatment parameters of focused ultrasound therapy in the future.

摘要 I
Abstract III
目錄 V
圖目錄 VI
表目錄 VIII
第一章 緒論 1
1.1 血腦屏障簡介 1
1.2 增加血腦屏障通透性的方法 2
1.3 聚焦式超音波誘發血腦屏障開啟的機制 3
1.4 目前監控血腦屏障開啟後腦部變化的方法 5
1.4.1 磁振造影(Magnetic Resonance Imaging, MRI) 5
1.4.2 對比增強超音波造影(Contrast Enhanced Ultrasound Imaging) 6
1.4.3 光聲造影(Photoacoustic Imaging) 7
1.5 血液與腦組織逆散射係數的比較 9
1.6 研究動機與目的 11
第二章 系統架構與實驗方法 12
2.1 聚焦式超音波參數測試 12
2.1.1 聚焦式超音波探頭聲壓校正 12
2.1.2 聚焦式超音波發射波型設計及參數 16
2.2 基於內源性對比機制之超音波時間強度曲線 18
2.3 高頻超音波小動物影像系統與聚焦式超音波系統之整合 19
2.3.1 系統架構 19
2.3.2 實驗參數與流程 20
2.3.3 訊號處理 24
2.4 光聲與聚焦式超音波整合系統 27
2.4.1 系統架構 27
2.4.2 實驗參數與流程 29
2.4.3 訊號處理 31
2.5 實驗動物及處理 32
2.6 組織切片與染色 34
第三章 實驗結果與討論 36
3.1 聚焦式超音波開啟血腦屏障之定位 36
3.2 超音波時間強度曲線 39
3.2.1 M1腦區對照組超音波時間強度曲線 39
3.2.2 M1腦區出血情況超音波時間強度曲線 41
3.2.3 M1腦區未出血情況超音波時間強度曲線 43
3.2.4 M1腦區左、右腦之超音波時間強度曲線比較 45
3.2.5 M2、M1+M2腦區之超音波時間強度曲線 47
3.2.6 M2、M1+M2腦區之左、右腦超音波時間強度曲線比較 48
3.3 開啟血腦屏障未出血情況光聲時間強度曲線 49
第四章 結論與未來工作 52
4.1 結論 52
4.2 未來工作 54
4.2.1 改善實驗設備與方法 54
4.2.2 TdT-mediated dUTP-biotin Nick end Labelic (TUNEL)染色 法確認細胞受損 54
4.2.3 以腦電圖(Electrocorticogram, ECoG)觀察開啟血腦屏障後的 行為反應 55
4.2.4 以盲蔽訊號源分離技術(blind source separation, BSS)分離出 血與缺血的時間強度曲線 55
參考文獻 56

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