使用擴散頻譜磁振造影重建人腦預設模式迴路之結構連結

平靜狀態功能性磁振造影研究中學者發現，血氧濃度相依對比訊號的低頻震盪在大腦中許多分散區域間有時間上的相關性，這些時間上的相關性被認為反映出大腦內部迴路中關於思考、情緒、認知、運動等功能的連結性，這些內部迴路被稱為平靜狀態迴路。在這些內部迴路之中有一個迴路在平靜狀態時表現出最強的功能連結，這個迴路所包含的區域有左右側後扣帶回�楔前葉區、左右側前額葉區、及左右側下頂葉區，此迴路被稱為人腦的預設模式迴路。為了找到預設模式迴路所相對應的結構連結，必須使用高角度解析度的擴散磁振造影方法來正確重建大腦內神經交錯區域的神經走向。本研究結合擴散頻譜磁振造影以及平靜狀態功能性磁振造影來重建預設模式迴路所對應的結構連結，四名自願者參與了本研究，每位受試者均接受以下三種磁振影像掃描：擴散頻譜磁振造影、平靜狀態功能性磁振造影、以及T2權重影像。我們發現數條解剖上已知的白質神經纖維參與了預設模式回路肩的信息傳遞。同側腦區間連結由以下三組連結形成：前額葉和後扣帶回�楔前葉區間由扣帶回以及上縱束的第一分枝所連結；而楔前葉和下頂葉區則是由皮質間的弓狀纖維所連結；前額葉和下頂葉區由額葉枕葉束連結。對側腦區間連結部份，左右側前額葉由胼胝體膝狀體所連結，左右側下頂葉、左右側後扣帶回�楔前葉區間則是由胼胝體壓部所連結。本研究建立了一套標準作業流程來分析平靜狀態功能性磁振造影及擴散頻譜磁振造影，未來會將此分析平台應用於觀察精神分裂症在兩種影像技術下的影像特徵，期望能夠找到足以診斷精神分裂症的影像生物標記。

關鍵字

平靜狀態功能性磁振造影；擴散頻譜磁振造影；腦功能影像；磁振造影

並列摘要

Resting-state functional magnetic resonance imaging (fMRI) demonstrated that the low frequency fluctuation of blood oxygen level-dependent (BOLD) showed temporal correlation of widely separated brain regions during rest. The temporal correlations are considered to reflect the inherence functional connectivity of brain network which corresponding to thought, intended speech and emotions. These networks were called resting-state networks (RSNs). One RSN showed highest functional connectivity during rest, the network including brain regions such as posterior cingulum /precuneus cortex (PCC), medial prefrontal lobe (MF), left and right inferior parietal lobes (IPL and IPR) are considered as brain default network work (DMN). In order to find the structural core of MDN, we employ a diffusion acquisition scheme at high angular resolution which capable to reconstruct complex intra-voxel fiber structure. In the present study, we combined diffusion spectrum image (DSI) and resting-state fMRI to reconstruct the whole structural network within DMN. Four right-handed adults were recruited in the study. All images were acquired on a 3T MRI system (Trio, Siemens, Erlangen, Germany). The acquisition protocol including (1) resting-state fMRI with a gradient echo EPI. Patients were asked to stare a cross in the middle of the screen. (2) DSI with a spin-echo diffusion EPI. (3) trans-axial T2-weighted image with spin echo sequence. We found that within DMN, existing known structural white matter connections between almost all DMN nodes. The MFC and PCC were connected by cingulum bundle and one branch of superior longitudinal fasciculus. The PCC and bilateral inferior parietal lobe were connected by cortico-cortical arcuate fibers. The MFC and bilateral inferior parietal lobe were connected by fronto-occipital fasciculus. Bilateral inferior parietal lobes and bilateral PCC regions were connected by splenium of corpus callosum. The bilateral MFC were connected by genu of corpus callosum. In the present we established a standard operation protocol (SOP) to analyze resting-state fMRI and DSI images. Future work is aim to apply the SOP to images of schizophrenia patients, to observe pathological changes on images. We are looking forward to find an image biomarker to diagnose schizophrenia.

並列關鍵字

resting-state fMRI ； diffusion spectrum image ； DSI,brain imaging technique ； magnetic resonance image

參考文獻

Basser, P. J., Mattiello, J., & LeBihan, D. (1994a). Estimation of the effective self-diffusion tensor from the NMR spin echo. J Magn Reson B, 103(3), 247-254.

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使用擴散頻譜磁振造影重建人腦預設模式迴路之結構連結

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