臺灣博碩士論文加值系統

腦電圖以及功能性核磁共振影像都是非侵入式神經顯影方式，它們分別提供了毫秒等級的時間解析度的神經反應以及毫米等級的空間解析度。在測量兩者資料時，可以是分開量測或同時量測。在實驗需要特別排除因記憶或學習效應造成的影響時，同時量測腦電圖和功能性磁振影像可以排除因兩次量測間差異造成的偏差。可是在同時收錄腦電圖及功能性磁振影像時腦電圖會受到在高磁場下的心搏產生的心搏假影及梯度線圈開關產生的梯度假影劇烈影響。因梯度假影的大小百倍於神經反應，並且梯度假影對受試者移動敏感，在經過信號處理減除梯度假影後，其殘值仍會影響腦電圖的品質。為降低梯度假影影響，我們提出將快速的simultaneous multi-slice inverse imaging(SMS-InI)序列和腦電圖間歇掃描。可預期在沒有掃描的區間(每2秒鐘內的1.9秒)可以提升腦電圖的品質，同時SMS-InI也維持與傳統Echo Planar Image(EPI)同等級的靈敏度及空間解析度。經由時頻分析我們知道使用傳統EPI序列造成的梯度假影會在固定頻率有最大的影響，所以我們激發15赫茲穩態視覺相關電位以比較間歇同時量測SMS-InI的腦電圖與同時量測傳統EPI的腦電圖及的品質。我們使用SMS-InI及腦電圖的間歇掃描量測到可以與在磁振造影室外量測的腦電圖相比的15赫茲穩態視覺相關電位以及可以與EPI相提並論的血動力反應圖。此種間歇式掃描腦電圖及SMS-InI 可適用於對腦電圖品質較有要求的實驗，例如讓功能性磁振影像使用發作間期癲癇樣放電(inter-ictal discharges, IID)時間點定位癲癇病患在大腦中激發放電的位置。

Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) can be combined to provide millisecond resolution and millimeter resolution of neuronal and hemodynamic activity. EEG and fMRI can be recorded concurrently or separately for data integration. In experiments considering memory or learning effects, concurrent EEG-fMRI is preferable to avoid bias due to separate measurements. In concurrent EEG-MRI recording, EEG is heavily distorted by pulse artifacts, which are caused by heartbeats in a strong magnetic field, and gradient artifacts, which are caused by repetitive gradient coil switching during MRI acquisition. Because GA is hundreds times larger than typical evoked neuronal responses and GA is very sensitive to movements, the residue of GA after GA suppression can significantly degrade EEG quality.
We propose to interleave simultaneous multi-slice inverse imaging (SMS-InI) concurrently with EEG. In this way, EEG recorded with gradient-artifact-free intervals (1.9-s in every 2-s) is expected to have high quality, while SMS-InI provides comparable sensitivity and spatiotemporal resolution like EPI. We used SMS-InI-EEG to measure 15-Hz steady-state visual evoked potentials comparable with EEG recorded outside MRI and the hemodynamic responses comparable with EPI. The interleaved SMS-InI-EEG can be applied to measurements sensitive to EEG quality, such as localizing irritative zones of inter-ictal discharges (IID) in epilepsy patients using fMRI based on IID timing.

論文審定書 #
Acknowledgment 1
中文摘要 2
Abstract 3
List of Figures 6
List of Tables 6
Chapter 1. Introduction 7
Chapter 2. Methods 14
2-1. MRI acquisition 14
2-2. EEG acquisition 16
2-3. Participant and Instructions 16
2-4. EEG preprocessing 17
2-5. EEG source estimation 18
2-6. Functional MRI preprocessing 19
2-7. EEG evaluation 19
2-8. Data analysis of EPI and SMS-InI 20
Chapter 3. Results 22
3-1. EEG results 22
3-2. Functional MRI results 28
Chapter 4. Discussions and Conclusions 31
Chapter 5. Appendices 36
5-A. Average artifact subtraction [25] 36
5-B. Heartbeat detection 37
5-C. Optimal basis set (OBS) subtraction for pulse artifact [36] 38
References 41

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