以擴散張量體素分析方法偵測慢性腎臟患者之腦白質微變化

Subtle white matter alternations in patients with Chronic Kidney Disease: A Voxelwise Diffusion Tensor Imaging analysis

林佳儒(Jia-Ru Lin)

指導教授 ： 周銘鐘

高雄醫學大學/健康科學院/醫學影像暨放射科學系碩士在職專班/碩士(2016年)

摘要

目的
擴散張量影像的體素分析方法為目前許多腦神經科學研究者探究腦部白質纖維的有力工具之一，不論是在神經纖維的擴散方向、偵測病變區域更甚者是大腦神經網路連結的運用，利用磁振造影儀器收集影像利用後端處理科技可以找出許多線索及突破，因此本次研究希望能以擴散張量的體素分析方式來偵測到腦部中肉眼還未可見的微細結構上的變化，找出腎臟病患者之腦部白質病變區域。
材料與方法
本次研究使用 3.0T GE Medical Systems 磁振造影儀器對28位患有慢性腎臟疾病者 (男：女＝15：13) 進行影像收集，並且收集腎絲球過濾率 (GFR)，將第一期與第二期患者視為對照組，而第三期至第五期患者視為實驗組，分別收集T1權重影像、T2權重影像，FLAIR影像及擴散張量影像。利用擴散張量影像進行影像對位、修正渦電流扭曲、計算擴散量化指標，包括：擴散不等向性 (FA)、軸向擴散度 (AD)、徑向擴散度 (RD)、平均擴散度 (MD)，並且在空間標準化後進行體素統計分析。
結果與討論
實驗組的FA數值下降且AD、RD、MD數值皆上升，表示水分子在實驗組的腦部白質區域有較多的擴散情形發生，且在實驗結果中也順利偵測到在白質纖維上已有微細結構被破壞的區域，可得出該疾病的進程的確是會對腦部造成破壞，此外該研究也發現在特定的腦白質區域中 GFR與 FA有顯著負相關，而與 AD、RD、MD 均有顯著正相關。
結論
擴散張量的體素分析方法是偵測肉眼尚不可見的微小變化之有利研究工具，研究發現腎臟病患者之腦部組織有微小變化，並且與腎絲球過濾率呈顯著相關，因此擴散張量的體素分析是一個有用的影像處理方法，未來若能建立起一套模式便於臨床應用，相信對於許多會造成腦部受損的疾病之預期能有更多預防性及診斷性。

關鍵字

擴散張量 ； 體素分析 ； 慢性腎臟病

並列摘要

Purpose
The voxel-based analysis of diffusion tensor imaging (DTI) is a powerful technology capable of exploring the white matter alternations caused by neurological diseases. With proper image post- processing, DTI can provide some clues and information on diffusion directions of neural fibers and detect altered brain tissues. Thus, we devote our efforts to detect the subtle and invisible alternations of the brain white matter tissue, with the use of voxel-based DTI analysis in patients with chronic kidney disease (CKD).

Materials and Methods
In this study, twenty-eight patients (male: female= 15:13) who suffered (CKD) were enrolled and all brain MR imaging data were acquired from a 3.0 T MRI scanner (GE Medical Systems ). Patients were divided into two groups according to their CKD stage. The group 1 consisted of patients with CKD stage 1 and 2, whereas the group 2 included patients with CKD stage 3 to 5. In addition to glomerular filtration rate (GFR), all of patients were scanned to acquire their T1 weighted image, T2 weighted image, FLAIR image and DT image. For DTI data, after performing image co-registration and eddy-current distortion correction, DTI indices were calculated and were spatially normalized for voxelwise statistical analysis.

Results and Discussion
The patients with CKD stage 3 to 5 had significantly decreased FA values but significantly increased AD, RD, and MD in several white matter regions than the patients with CKD stage 1 and 2. In all patients, the FA values were negatively correlated, whereas AD, RD and MD values were positively correlated with GFR and CKD stages. That is to say, water molecules in those white matter regions had higher diffusivity and lower diffusion anisotropy significantly correlated with the kidney functions.

Conclusions
The voxel-based analysis of DTI is a useful method to detect the subtle white matter alternations in CKD patients. If we can establish a convenient post-processing pipeline for clinical applications, the voxelwise DTI analysis will be helpful to early predict and prevent the progression of many diseases that impair brain tissue.

並列關鍵字

Diffusion Tensor ； Voxel-based analysis ； Chronic kidney disease

參考文獻

參考資料

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