臺灣博碩士論文加值系統

功能性磁振造影(Functional magnetic resonance imaging，fMRI)使用血氧濃度相依程度 (oxygenation level-dependent，BOLD)，量測神經活化所帶來之代謝和血流變化。BOLD信號已大量被應用於大腦神經元活動量測，並廣泛應用於臨床檢查。最近的研究中，發現BLOD信號會被高碳血酸症影響，這種現象可能會引起fMRI研究結果誤判。二氧化碳(CO2) 會使腦血管擴張並使腦血流顯著的增加，而血流的改變會影響到在fMRI實驗過程中的訊號。大多數高血酸症下BOLD效應的fMRI研究使用長時間區塊刺激評估。本研究中，取代長時間區塊刺激方式，本實驗以事件相關fMRI刺激方式研究HRF吸入不同CO2濃度下的變化。
這個實驗包括10位健康自願者，吸入不同濃度二氧化碳和不同刺激持續時間，每位受測者共有16個實驗。研究不同的視覺刺激持續時間(1、2、4、8秒)和各種CO2濃度(室內空氣、3%、5%、7%)的HRF曲線。並使用BLOD峰值、半高全寬和峰值時間，來評估HRF曲線形狀。
我們研究顯示，吸入二氧化碳的成分增加BLOD峰值會降低。吸入二氧化碳的成分增加與半高全寬、峰值時間持續時間延長成正比。此研究結果，符合腦血管保護機制，即在低濃度CO2時，維持穩定不變的狀態，但在高濃度CO2時，引起劇烈回饋反應。 本研究結論証實吸入CO2對HRF的影響。

Functional magnetic resonance imaging (fMRI) using blood oxygenation level-dependent (BOLD) contrast has appeared to measure vascular oxygenation change due to neuron activity. BOLD signals have been used to investigate the cerebral neuronal activities and widely applied to clinical examinations. Recently, it is found that BOLD signals could be altered solely by hypercapnia. Such phenomenon might cause misinterpretation of fMRI studies with concurrent hypercapnia. Carbon dioxide (CO2) is a potent vasodilator that could increase the cerebral blood flow prominently. Most fMRI studies used long-time box-car stimulus design for evaluating BOLD effect in hypercapnia. In this study, instead of long-time box-car stimulus; event-related fMRI (ER-fMRI) with short-time visual stimulus is applied to investigate the transient hemodynamic response function (HRF). We aim the HRF change by different CO2 concentration inhalation.
The study consisted of ten healthy volunteers with sixteen experiments for each subject under different fractions of inhaled CO2 and stimulus duration. The time curve of HRF is investigated in different visual stimulus duration (1, 2, 4 and 8 sec) and various CO2 concentration (room air, 3%, 5% and 7%). Peak-BOLD, full-width-at-half-maximum (FWHM) and time-to-peak (TTP) were used to evaluate HRF shape.
Our study showed that the Peak-BOLD percent changes decrease corresponding to the increase of the inhaled CO2 fractions. The duration for FWHM and TTP prolongs proportional to the increase of inhaled CO2 fractions. This finding is consistent with the concept of cerebrovascular reserve, which might remain unchanged in lower CO2 fractions but be damped in higher CO2 fractions. In conclusion, we provide important concepts in HRF by the influence of inhaled CO2.

中文摘要......................................................................................................................... i
Abstract .......................................................................................................................... ii
圖目錄........................................................................................................................... vi
表目錄........................................................................................................................... ix
第一章、前言................................................................................................................ 1
1-1研究背景 ......................................................................................................... 1
1-2 研究目的及其重要性 .................................................................................... 2
1-3 文獻回顧 ........................................................................................................ 3
第二章、研究理論........................................................................................................ 4
2-1 大腦構造 ........................................................................................................ 4
2-2 功能性磁振造影(fMRI) .................................................................................. 6
2-3 血碳酸過多（Hypercapnia） ........................................................................ 8
2-4-誘發刺激 ......................................................................................................... 9
第三章、研究方法與材料.......................................................................................... 12
3-1實驗對象 ....................................................................................................... 12
3-2氣體準備與生理參數監測 ........................................................................... 12
3-3實驗設計 ....................................................................................................... 15
3-4影像設計參數 ............................................................................................... 16
3-5影像分析 ....................................................................................................... 18
3-5.1 SPM 簡介 .......................................................................................... 18
3-5.2 SPM影像處理流程 ........................................................................... 19
3-5.3 影像空間前置處理 ........................................................................... 20
3-5.3(a) 圖像校準(Slice timing correction) ....................................... 20
3-5.3(b) 頭動校正(Realign) ............................................................... 21
3-5.3(c) 影像對位運算(Coregister) ................................................... 22
3.5.3(d) 影像標準化（Normalise） .................................................. 22
3.5.3(e) 一般線性模型 ....................................................................... 23
3-5.4 影像後處理流程 ............................................................................... 25
3-5.4(a)自動腦區名稱標記工具 AAL............................................... 26
3-5.4(b) 通用遮罩 MASK ................................................................. 29
3-5.4(c) 曲線擬合 ............................................................................... 31
3-5.4(d) 半高全寬Full width at half maximum (FWHM) ................. 32
3-6 統計方法 .............................................................................................. 32
第四章、結果.............................................................................................................. 33
4-1二氧化碳時間刺激的BOLD變化 .............................................................. 34
4-2刺激時間下不同二氧化碳濃度的血氧訊號曲線比較 ............................... 37
4-3半高全寬相關數據 ....................................................................................... 40
4-4 3D呈現視覺皮質反應區 ............................................................................. 43
第五章、討論與結論.................................................................................................. 44
參考文獻...................................................................................................................... 47

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