Evaluation and comparison on Fast Spin Echo with Keyhole MRI
| Autor: | Wei-Yu Peng, 彭威瑀 |
|---|---|
| Rok vydání: | 2009 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 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”. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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