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研究生:彭威瑀
研究生(外文):Wei-Yu Peng
論文名稱:快速自旋回波跟磁振造影匙孔技術的效能評估比較
論文名稱(外文):Evaluation and comparison on Fast Spin Echo with Keyhole MRI
指導教授:朱唯勤朱唯勤引用關係
指導教授(外文):Woei-Chyn Chu
學位類別:碩士
校院名稱:國立陽明大學
系所名稱:醫學工程研究所
學門:工程學門
學類:生醫工程學類
論文種類:學術論文
論文出版年:2009
畢業學年度:97
語文別:中文
論文頁數:73
中文關鍵詞:磁振造影快速自旋回波磁振造影匙孔技術影像品質
外文關鍵詞:Magnetic Resonance Imaging(MRI)Fast Spin Echo(FSE)Keyhole MRIImaging quality
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由於磁振照影在軟組織跟器官上可以獲得較高的解析度,所以近年來它在醫療診斷分析上是不可或缺的技術。但是在追求高解析度的時候,會需要較長的取像時間,而時間長很容易就會產生運動假影;因此為了此種情況,一些快速照影的技術便應運而生。其中有兩種技術都是基於自旋回波(Spin-Echo)的原理所產生的,分別是「 快速自旋回波(FSE) 」與「磁振造影匙孔技術(Keyhole)」。
「快速自旋回波」是目前已實際應用於臨床上的技術,其確實可以在維持原始影像的訊雜比(SNR)下,有效地減少造影所需時間,但是其亦有缺點存在,如:影像會產生模糊化的假影等。「磁振造影匙孔技術」則是在研究上使用的方法,目前尚未實際應用在臨床醫療上的技術。根據以往的文獻記載,其可以在加快到一定速度內有效地減少造影時間,且也不會有很明顯的缺點存在。所以,本研究是希望藉由影像的數種性質去量化分析在相同加速度下,「磁振造影匙孔技術」與「快速自旋回波」在影像品質上的優缺點,並去評估「磁振造影匙孔技術」是否可在某些臨床診斷方面可取代「快速自旋回波」。
經由實驗結果的觀察,可發現到「磁振造影匙孔技術」與「快速自旋回波」各有優缺點存在:兩者均不會產生幾何失真情形、「快速自旋回波」的訊雜比會比「磁振造影匙孔技術」較佳、但是在低對比度鑑別率方面,會因為「快速自旋回波」的模糊化假影情況比「磁振造影匙孔技術」更加嚴重,所以在低對比度鑑別率方面會是「磁振造影匙孔技術」更勝一籌。此外,在T1權重影像部分,我們利用了老鼠活體實驗去確認「磁振造影匙孔技術」可使掃描時間縮短至 1/12 到 1/14,且亦維持原始影像的大部分品質,而「快速自旋回波」由於每條訊號的TE均不一樣,當掃描時間越來越短時,所收到的部分訊號已經不屬於「純T1權重影像」,所以只能使掃描時間縮短至 1/6 到 1/8;因此,在T1權重影像上,使用「磁振造影匙孔技術」來做快速造影,比起「快速自旋回波」會是更佳的選擇。雖然本研究並未對T2權重影像做實驗結果分析,但是單就從原理上來講,當「磁振造影匙孔技術」使掃描時間縮短至一定時間內後,會因為無法更新到高頻的資訊,而產生邊緣細節失真的情況,所以通常會選擇在高於原始影像的1/14 掃描時間情況下,使用「磁振造影匙孔技術」。至於「FSE」在T2權重影像方面可使掃描時間縮短至 1/10到 1/32,因此這方面會是「FSE」比「Keyhole」更佔優勢。
綜合研究結果,「磁振造影匙孔技術」確實是一項可應用於臨床醫療上的快速造影技術,特別是在要掃描的物體本身是較低對比時,還有在T1權重影像上,「磁振造影匙孔技術」都比「快速自旋回波」更佔優勢。
Because its higher-resolution and good image contrast to soft tissue and organ, magnetic resonance imaging (MRI) technology has become one of the necessary methods on medical diagnostic techniques in recent years. However, the higher resolution we are pursuing, the longer time it will take to obtain the images, which will lead to motion artifact. For this reason, some fast image-capturing techniques had appeared. Two of these techniques are based on spin-echo is “Fast Spin Echo (FSE)”, and the other is”Keyhole”.
“FSE” has been used in clinical fields which can maintain the SNR of the original image. It is very effective to reduce imaging time; however, there is a room for improvement, such as image blurring. ”Keyhole” has remains as an academic research technique; nevertheless, according to the previous researches, it can speed up to some extent to reduce imaging time effectively.
Thus, the purpose of this study is to analyze and quantize the ”Keyhole” and “FSE” techniques in their image quality under the same acceleration, and to evaluate if the “FSE” could be replaced by ”Keyhole” in some clinical diagnosis cases.
Based on the results, it can be found that not only”Keyhole” but “FSE” has its advantages and disadvantages. Neither Keyhole nor “FSE” produces geometric distortion. “FSE” is better than”Keyhole” in SNR, while”Keyhole” is better than “FSE” in low-contrast object detectability, because the fuzzy artifacts of FSE is much more serious than Keyhole. Also, in vivo rat experiment, it is confirmed that the scanning time can be shorten 1/12 to 1/14 with “Keyhole” and Keyhole can maintain most SNR as well as CNR value in the original image, while the scanning time of “FSE” can only be shortened 1/6 to 1/8; that result from each different TE in its signal, while the scanning time is shorter and shorter, the parts of the received signal does not belong to the “Pure T1-weighted image.” Besides, the TEeff will be bigger and bigger with the increase of the ETL, leading to the decrease of SNR and CNR. Therefore, the T1-weighted images of “Keyhole” will be a better choice when performing fast MR T1-weighted imaging.
Though this study analyze no experimental result on T2-weighted images, principally, while “Keyhole MRI technology” shorten the scanning time to some certain period, distortion of the detail edge will be produced. That’s the reason why we always choose “Keyhole MRI” while we spend less than 1/14 on scanning, but “FSE” will be better than Keyhole, while “FSE” can shorten scanning time from 1/10 to 1/32.
To come to the conclusion, “Keyhole” can be applied to fast-imaging on clinic, especially when the scanned objects are relatively lower contrast ratio. In addition, the T1 weight image of “FSE” is much more advantageous than”Keyhole”.
目錄
致謝 ii
摘要 iv
Abstract vii
目錄 ix
表目錄 xi
圖目錄 xii
1 第一章 導 論 1
1.1 簡介 1
1.2 研究動機與目的 3
1.3 論文架構 5
2 第二章 磁振造影原理 7
2.1 Spin-Echo原理 7
2.2 Fast Spin Echo原理 10
2.3 Keyhole原理 16
2.3.1 Keyhole原理簡介 16
2.3.2 Keyhole文獻回顧 19
3 第三章 實驗材料與方法 21
3.1 ACR假體實驗 21
3.1.1 實驗材料 21
3.1.2 實驗設備 22
3.1.3 實驗軟體 23
3.1.4 實驗方法 23
3.1.5 實驗參數 24
3.1.6 Keyhole影像的模擬建立 25
3.2 老鼠活體實驗 26
3.2.1 實驗材料 26
3.2.2 施打對比劑流程 27
3.2.3 實驗設備 28
3.2.4 實驗方法 28
3.2.5 實驗參數 29
3.2.6 Keyhole影像的模擬建立 29
4 第四章 實驗結果 31
4.1 假體實驗結果 31
4.1.1 Geometric accuracy 31
4.1.2 Signal to Noise Ratio(SNR) 36
4.1.3 Low-contrast object detectability 38
4.2 老鼠活體實驗結果 42
4.2.1 Keyhole實驗結果 44
4.2.2 FSE實驗結果 48
5 第五章 討論 50
5.1 假體實驗 50
5.2 老鼠活體實驗 54
6 第六章 結論與未來展望 57
7 參考文獻 59
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