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http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/34372完整後設資料紀錄
| DC 欄位 | 值 | 語言 |
|---|---|---|
| dc.contributor.advisor | 鍾孝文 | |
| dc.contributor.author | Hing-Chiu Chang | en |
| dc.contributor.author | 曾慶昭 | zh_TW |
| dc.date.accessioned | 2021-06-13T06:05:20Z | - |
| dc.date.available | 2006-06-21 | |
| dc.date.copyright | 2006-06-21 | |
| dc.date.issued | 2006 | |
| dc.date.submitted | 2006-06-15 | |
| dc.identifier.citation | [1] Mansfield P (1977), 'Multi-planar image formaiton using NMR spin echoes.' J Physics C Solid State Phys 10: L55-L58.
[2] Rzedzian RR, Pykett IL (1987), “Instant images of the human heart using a new, whole-body MR imaging system.” Am J Roentgenol 149:245-250. [3] Johnson G, Hutchinsion JMS (1985), “The limitations of NMR revalled echo imaging techniques.” J Magn Reson 63:14-30. [4] Rosen B, Belliveau JW, Chien D (1989), “Perfusion imaging by nuclear magnetic resonance.” Magn Reson Q 5:263-281. [5] Turner R, Le Bihan D (1990), “Single-shot diffusion imaging at 2.0 Tesla.” J Magn Reson 86:445-452. [6] Kwong KK, Belliveau JW, Chesler DA et al (1992), “Dynamic magnetic resonance imaging of human brain activity during primary sensory stimulation.” Proc Natl Acad Sci USA 89:5675-5679. [7] Paul S. Morgan, Richard W. Bowtell, Dominick J.O. Mclntyre, Brian S. Worthington (2004), “Correction of Spatial Distortion in EPI Due to Inhomogeneous Static Magnetic Fields Using The Reversed Gradient Method.” JMRI 19:499-507. [8] Fu-Nien Wang, Teng-Yi Huang, Fa-Hsuan Lin, Tzu-Chao Chuang, Nan-Kuei Chen, Hsiao-Wen Chung, Cheng_yu Chen, and Kenneth K. Kwong (2005), “PROPELLER EPI: an MRI technique suitable for diffusion tensor imaging at high field strength with reduced geometric distortions.” MRM 54:1232-1240. [9] Jezzard P and Balaban RS (1995). 'Correction for geometric distortion in echo planar images from B0 field variations.' Magn Reson Med 34(1): 65-73. [10] Hsuan Chang, J. Michael Fitzpatrick (1992), “A technique for accurate magnetic resonance imaging in the presence of field inhomogeneities.” IEEE TRANS MED Vol.11, No.3, SEP. [11] Pipe JG (1999). 'Motion correction with PROPELLER MRI: application to head motion and free-breathing cardiac imaging.' Magn Reson Med 42(5): 963-9. [12] Pipe JG, Farthing VG and Forbes KP (2002). 'Multishot diffusion-weighted FSE using PROPELLER MRI.' Magn Reson Med 47(1): 42-52. [13] Chen NK and Wyrwicz AM (2001). 'Optimized distortion correction technique for echo planar imaging.' Magn Reson Med 45(3): 525-8. [14] Chuang TC, Huang TY, Lin FH, Wang FN, Chung HW, Chen CY and Kwong KK (2004). 'Propeller EPI with SENSE parallel imaging using a circularly symmetric phase array RF coil.' Proc Intl Soc Magn Reson Med, Kyoto, Japan, 535. | |
| dc.identifier.uri | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/34372 | - |
| dc.description.abstract | 本論文展示一種平面回訊影像幾何扭曲的修正方法。這個方法是建基於反向梯度磁場方法，它是利用兩張影像在極性相反的相位編碼梯度磁場下，幾何扭曲在影像上的剛好呈現相反的表現，最後利用幾何扭曲在兩張影像上相反的特性所提供的資訊，來修正影像。但是，這個修正方法在修正一些低信號部份時，由於缺乏幾何扭曲的資訊，因此導致在這些低信號部份產生修正上的錯誤。在實行反向梯度磁場方法時，加入了位移表示圖像 (displacement map) 的概念去減低在低信號部份的修正錯誤。這個位移表示圖像的概念包括了除去位移表示圖像上錯誤的資訊、進行表面近似和濾波。在3T高磁場下實驗的結果顯示，相對於本來的反向梯度磁場方法，改良反向梯度磁場反法修正的影像展示出減低影像的幾何扭曲以及在低信號部份錯誤的修正。把改良反向梯度磁場法應用在螺旋槳式磁振平面回訊影像上，對每一個葉片資料作額外的修正，在高解析度擴散張量影像上有一定的優勢，可以提高影像的品質以及在臨床的應用。 | zh_TW |
| dc.description.abstract | A technique suitable for echo planar imaging (EPI) geometrical distortion correction is presented in this thesis. The method is based on reversed gradient method (RG) using phase-encoding gradient with reversed polarity that produces distortion in opposite direction, from which the information on the difference in spatial displacements is then used to correct for distortion. However, this method is problematic in regions with low signals because of a lack of information on distortions which leads an error correction in regions with low signals. The implementation of reversed gradient method induced a displacement map concept to reduce the error correction in regions with low signals. The displacement map concept consists of eliminating error displacement map, surface fitting and filtering. Experimental results on a 3.0 Tesla MR system showed that the modified reversed gradient method corrected images exhibit substantially reduced geometric distortions and correction error in regions with low signals compared with original reversed gradient method. Applied reversed gradient method in high-resolution DTI using PROPELLER EPI to extra correct each blade, shows benefits from the modified reversed gradient method. It can increase the image quality for routine diffusion tensor imaging applications in clinical practice. | en |
| dc.description.provenance | Made available in DSpace on 2021-06-13T06:05:20Z (GMT). No. of bitstreams: 1 ntu-95-R93921048-1.pdf: 3282622 bytes, checksum: 482529cd0a6b5c531ac567b3444189d8 (MD5) Previous issue date: 2006 | en |
| dc.description.tableofcontents | Abstract 1
中文摘要 2 1. INTRODUCTION 3 1.1 Echo Planner Imaging (EPI) and sequence 3 1.2 EPI geometrical distortion 6 1.3 Motivation 8 2. THEORY 10 2.1 Reversed gradient method 10 2.2 Modified reversed gradient method with displacement map concept 16 3. MATERIALS AND METHODS 19 3.1 Phantom and subjects 19 3.2 Data processing 20 4. RESULTS 25 4.1 Correction of phantom and brain EPI image at 3.0T MRI scanner 25 4.2 Correction of diffusion tensor imaging at 1.5T MRI scanner 28 5. APPLICATION: PROPELLER EPI diffusion weighted imaging 32 5.1 Introduction of PROPELLER EPI 32 5.2 PROPELLER EPI with reversed gradient method 36 5.3 Result: high resolution diffusion tensor imaging at 3.0T MRI scanner 39 5.4 Discussion 46 6. DISCUSSION AND CONCLUSION 48 6.1 Discussion of modified reversed gradient method 48 6.2 SNR in reversed gradient method 48 6.3 Conclusion 51 7. REFERENCE 52 8. APPENDIX I 54 2D polynomial surface fitting 54 | |
| dc.language.iso | en | |
| dc.subject | 擴散張量影像 | zh_TW |
| dc.subject | 平面回訊影像 | zh_TW |
| dc.subject | 反向梯度磁場法 | zh_TW |
| dc.subject | 螺旋槳式磁振平面回訊影像 | zh_TW |
| dc.subject | 幾何扭曲 | zh_TW |
| dc.subject | gradient revesal | en |
| dc.subject | Echo Planar Imaging | en |
| dc.subject | EPI | en |
| dc.subject | geometric distortion | en |
| dc.subject | reversed gradient | en |
| dc.subject | PROPELLER EPI | en |
| dc.subject | diffusion tensor imaging | en |
| dc.subject | DTI | en |
| dc.title | 利用改良反向梯度磁場方法修正平面回訊影像的幾何扭曲：技術及其應用 | zh_TW |
| dc.title | Geometrical Distortion Correction in Echo Planar Imaging using A Modify Reversed Gradient Method: Techniques & Applications | en |
| dc.type | Thesis | |
| dc.date.schoolyear | 94-2 | |
| dc.description.degree | 碩士 | |
| dc.contributor.oralexamcommittee | 曾文毅,陳南圭,黃騰毅,柯正雯 | |
| dc.subject.keyword | 平面回訊影像,幾何扭曲,反向梯度磁場法,螺旋槳式磁振平面回訊影像,擴散張量影像, | zh_TW |
| dc.subject.keyword | Echo Planar Imaging,EPI,geometric distortion,reversed gradient,PROPELLER EPI,diffusion tensor imaging,DTI,gradient revesal, | en |
| dc.relation.page | 55 | |
| dc.rights.note | 有償授權 | |
| dc.date.accepted | 2006-06-15 | |
| dc.contributor.author-college | 電機資訊學院 | zh_TW |
| dc.contributor.author-dept | 電機工程學研究所 | zh_TW |
| 顯示於系所單位： | 電機工程學系 | |
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| ntu-95-1.pdf 未授權公開取用 | 3.21 MB | Adobe PDF |
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