臺灣博碩士論文加值系統

精神分裂症是一種非常普遍的精神疾病，其臨床上的症狀為幻聽、妄想、語言內容貧乏、認知功能受損及社交能力下降。目前認為精神分裂症為大腦結構及功能發生障礙之疾病，並且在許多研究中也證明患者在大腦兩側的溝通連結上有受損的現象。胼胝體為大腦中最大的白質神經纖維結構，其神經纖維會投射到不同的大腦皮質區，以負責左右腦之間的訊息傳遞。擴散張量造影是目前唯一以非侵入的方式重建神經纖維構造的技術，並可以利用其所產生的擴散張量指標係數（Diffusion tensor index）進一步量化大腦白質神經纖維的完整性及其細微的病理變化。

本研究中，我們將針對50 位精神分裂症患者及50 位正常受試者進行擴散張量磁振影，並使用機率性神經追蹤術，根據胼胝體神經纖維連結到不同的大腦皮質區的特性，建立新的胼胝體分區方法。並且計算出胼胝體各分區的部分非等向性擴散指標(Fractional Anisotropy, FA)、第一特徵值指標（First Eigen Value, FEV）及徑向擴散指標（Radial Diffusivity, RD）。利用上述之指標進行患者與正常受試者之間胼胝體神經纖維完整性之差異，以及探討臨床相關變數（患病時間長短、性別）所帶來的影響。

藉由機率性神經追蹤術及統計分析結果顯示精神分裂症患者在胼胝體之前額葉、前運動皮質區、後頂葉及枕葉的子區域其神經纖維完整性較正常受試者差。此外，胼胝體之前額葉子區域神經完整性與患病時間長短存在著非線性相關。並且我們進一步發現兩群組在性別上有不同的表徵。

本研究中，提供了精神分裂症患者於胼胝體神經纖維完整性缺損的量化證據，並且更進一步的指出患病時間長短以及性別所帶來的影響。此結果提供了精神分裂症患者在大腦兩側溝通連結功能低下的證據。

Schizophrenia is a mental disorder which the most common symptoms are hallucination, delusion and impairment in social cognition. Many studies have shown that schizophrenia patients might suffer from the impairments of interhemispheric information transfer. Corpus Callosum (CC) is the largest white matter (WM) structure which dominates the interhemispheric information transfer in the brain.Diffusion tensor imaging (DTI) provides a non-invasive method for visualization of WM pathways in human brain. Moreover, the DTI indices provide an quantitative method to examine the WM tracts integrity and subtle pathological changes.

DTI and structural MRI scans were obtained from 50 schizophrenia and 50 control subjects. Probabilistic tracking algorithm was used to obtain the CC topography since each portion of CC fibers connect to different brain cortices . Mean fractional anisotropy (FA),first eigen value (FEV), and radial diffusivity (RD) were compared on each callosal subdivision between the two groups. The relationships
between DTI indices and clinical variables, such as duration of illness, were investigated as well.

Compared with controls, decreased FA was found in the subdivions connecting to the prefrontal, premotor, posterior parietal, and occipital cortices in subjects with schizophrenia. Specifically, FA showed a non-linear correlation with the duration of illness in the subdivision connecting to the prefrontal cortex. In addition, the gender effect revealed different patterns in two groups.

This study provides a quantitative evidence for the reduction of inter-hemispheric brain connectivity in schizophrenia; meanwhile, the effects of duration of illness and gender were discussed. The finding may support the hypo-connectivity model of schizophrenia.

致謝 I
中文摘要 II
英文摘要 IV
目錄 VI
圖目錄 VIII
表目錄 X
第一章 緒論 1
1.1 研究動機 1
1.2 研究主題 4
1.3 論文架構 5
第二章 理論基礎與文獻討論 6
2.1 擴散磁振造影原理 6
2.1.1 水分子之擴散運動 6
2.1.2 擴散核磁共振訊號之量測 8
2.1.3 擴散張量造影原理 13
2.1.4 擴散張量影像之量化指標. 16
2.2 擴散張量磁振造影之不確定性 19
2.2.1 擴散張量不確定性 19
2.2.2 局部性參數估計 20
2.2.3 全域性參數估計 25
2.3 精神分裂症之相關背景 28
2.3.1 精神分裂症診斷準則及其症狀 28
2.3.2 精神分裂症相關假說 31
2.4 胼胝體於精神分裂症研究之應用 33
2.4.1 胼胝體功能與其重要性 33
2.4.2 胼胝體於精神分裂症之文獻探討 35
2.4.3 胼胝體分區之重要性 38
第三章 研究材料與方法 40
3.1 臨床磁振造影實驗及影像處理之主要作業流程 40
3.2 精神分裂症患者與健康受試者之選取標準 41
3.3 臨床磁振造影掃描參數設定 43
3.4 影像處理 45
3.4.1 影像前處理 45
3.4.2 胼胝體與大腦皮質ROI 選取標準 47
3.4.3 胼胝體之分區方法 49
3.5 統計分析 51
第四章 結果與討論 52
4.1 胼胝體分區拓譜學 52
4.2 胼胝體神經纖維完整性分析 54
4.3 病人組神經纖維完整性與患病時間長短之相關性分析 60
4.4 胼胝體神經纖維完整性之性別差異分析 63
第五章 未來展望與結論 67
5.1 未來展望 67
5.2 結論 69
參考文獻 71

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