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研究生:陳俊文
研究生(外文):Jyun-Wen Chen
論文名稱:磁共振熱治療監控之質子共振頻率位移權重造影
論文名稱(外文):Proton resonance frequency shift weighted imaging for the MR monitoring of the thermotherapy
指導教授:黃騰毅黃騰毅引用關係
指導教授(外文):Teng-Yi Huang
學位類別:碩士
校院名稱:國立臺灣科技大學
系所名稱:電機工程系
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2008
畢業學年度:96
語文別:英文
論文頁數:53
中文關鍵詞:磁化率高效能聚焦超音波磁化率權重造影磁共振影像監控質子共振頻率偏移質子共振頻率式磁化率權重造影
外文關鍵詞:SusceptibilityHIFUSWIMR monitoringPRF-shiftPRFSWI
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高能聚焦超音波(High Intensity Focused Ultrasound, HIFU),目前被證實能夠以非侵入的方式治療腫瘤,配合磁共振溫度影像的觀測,HIFU能準確的燒灼患部,並且不破壞週遭正常組織。由於燒灼時的局部溫度上升在磁振造影過程中所形成的梯度迴訊強度影像跟弛緩時間T1及質子密度PD等參數息息相關,也能夠顯示出相關的影像對比。即使對比是難以捉摸且只能提供性質上的訊息,但卻不需要基底相減(baseline subtraction)的方法來得到影像對比。因此當組織在燒灼的情況下發生運動位移時,並不會影響到梯度迴訊強度影像。由於燒灼區域組織溫度的上升所造成的質子共振頻率偏移跟磁化率所造成的頻率位移皆會導致質子不同程度的自旋行為。為了更進一步增強由燒灼時溫度造成的強度影像對比,在本論文裡提出了一項基於磁化率權重影像後處理方法,稱為質子共振頻率偏移權重影像(PRFSWI)應用於磁振造影引導聚焦超音波的應用來突顯質子共振頻率偏移所導致的影像對比。
Owing to the temperature dependence of most MRI parameters such as the longitudinal relaxation time T1 and the proton density, the magnitude images obtained by the proton resonance frequency based sequences also exhibit temperature-related image contrast. Although this contrast is relatively subtle and provides only qualitative information, it does not require baseline subtraction. Therefore, it’s suitable when the tissue motion is present. In this study, we aimed to further enhance the contrast of the magnitude image by a post-processing method similar to the recently advanced susceptibility-weighted imaging (SWI) method. SWI is a technique that can detect susceptibility differences in tissues and has been shown to be able to detect the hemorrhagic lesions and to reconstruct the whole-brain venogram. In MRI-guided focused ultrasound (MRIgFUS) applications, the proton resonance frequency dispersion induced by the local temperature elevation has the spin behavior similar to that of the susceptibility-related frequency shift. For this reason, we proposed to apply a SWI-like post-processing method, PRFSWI, to reconstruct the PRF-shift contrast for MRIgFUS.
Abstract i
中文摘要 ii
致謝 iii
Table of Contents iv
List of Figures vi
Chapter 1. Introduction 1
1.1 What is HIFU? 1
1.2 MRI monitoring 2
Chapter 2. Theory 5
2.1 Temperature-dependent MR parameters: PRF, T1 and
proton-density 5
2.2 Susceptibility weighted imaging (SWI) background 8
Chapter 3. Materials and Methods 10
3.1 Equipment 10
3.2 Data Acquisition Methods 11
3.2.1 Phantom experiment 13
3.2.2 Ex-vivo porcine liver experiment 13
3.2.3 In-vivo rabbit muscle experiment 14
3.3 Proton Resonance Frequency Shift Weighted Imaging
(PRFSWI) post-processing 15
3.3.1 Step 1: High-pass filtering 17
3.3.1.1 A region-growing algorithm for
phase unwrapping 18
3.3.1.2 K-space filter 24
3.3.2 Step 2: Scaling to phase mask 28
3.3.3 Step 3: Multiplying to magnitude image 31
3.4 Comparison of contrast-to-noise ratio (CNR) 36
Chapter 4. Results 37
Chapter 5. Discussion and conclusion 44
5.1 Discussion 44
5.1.1 Region-growing algorithm and k-space filter 44
5.1.2 SWI vs. PRFSWI 46
5.1.3 Optimization of m factor 46
5.1.4 PRFSWI enhancement 47
5.2 Conclusion 48
Chapter 6. Reference 49
Appendix 50
Chen, J., B. L. Daniel and K. B. Pauly (2006). "Investigation of proton density for measuring tissue temperature." J Magn Reson Imaging 23(3): 430-4.
Clement, G. T. (2004). "Perspectives in clinical uses of high-intensity focused ultrasound." Ultrasonics 42(10): 1087-93.
Haacke, E. M., Y. Xu, Y. C. Cheng and J. R. Reichenbach (2004). "Susceptibility weighted imaging (SWI)." Magn Reson Med 52(3): 612-8.
Ishihara, Y., A. Calderon, H. Watanabe, K. Okamoto, Y. Suzuki, K. Kuroda and Y. Suzuki (1995). "A precise and fast temperature mapping using water proton chemical shift." Magnetic Resonance in Medicine 34(6): 814-823.
Kennedy, J. E., G. R. Ter Haar and D. Cranston (2003). "High intensity focused ultrasound: surgery of the future?" Br J Radiol 76(909): 590-9.
Lewa, C. J. and Z. Majewska (1980). "Temperature relationships of proton spin-lattice relaxation time T1 in biological tissues." Bull Cancer 67(5): 525-30.
Quesson, B., J. A. de Zwart and C. T. Moonen (2000). "Magnetic resonance temperature imaging for guidance of thermotherapy." J Magn Reson Imaging 12(4): 525-33.
Sehgal, V., Z. Delproposto, E. M. Haacke, K. A. Tong, N. Wycliffe, D. K. Kido, Y. Xu, J. Neelavalli, D. Haddar and J. R. Reichenbach (2005). "Clinical applications of neuroimaging with susceptibility-weighted imaging." J Magn Reson Imaging 22(4): 439-50.
Tong, K. A., S. Ashwal, A. Obenaus, J. P. Nickerson, D. Kido and E. M. Haacke (2007). "Susceptibility-Weighted MR Imaging: A Review of Clinical Applications in Children." AJNR Am J Neuroradiol: ajnr.A0786.
Wang, Y., Y. Yu, D. Li, K. T. Bae, J. J. Brown, W. Lin and E. M. Haacke (2000). "Artery and vein separation using susceptibility-dependent phase in contrast-enhanced MRA." J Magn Reson Imaging 12(5): 661-70.
Wei, X. and I. Cumming (1999). "A region-growing algorithm for InSAR phase unwrapping." Geoscience and Remote Sensing, IEEE Transactions on 37(1): 124-134.
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