Title page for etd-0903111-002141


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URN etd-0903111-002141
Author Shi-jia Wu
Author's Email Address No Public.
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Department Electrical Engineering
Year 2011
Semester 1
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Optimization of contrast and signal homogeneity for high resolution 3D MRI of human brain at 1.5 Tesla
Date of Defense 2011-08-31
Page Count 103
Keyword
  • centric phase encoding
  • CNR
  • MP2RAGE
  • B1 inhomogeneity
  • linear phase encoding
  • MPRAGE
  • Abstract The inhomogeneous B1 field at higher main fields (B0) becomes more serious, leading to unsatisfactory MR image quality. To improve the signal homogeneity of routinely used T1-weighted image, usually acquired by a well-known sequence, Magnetization Prepared Rapid Acquisition Gradient Echo (MPRAGE), a new pulse sequence, Magnetization Prepared 2 Rapid Acquisition Gradient Echoes (MP2RAGE), was proposed in 2009. This technique acquires two sets of high-resolution three- dimentional images at different inversion times after a series of inversion pulses. After any of two simple calculations of the raw images (Ratio or MP2RAGE reconstruction), the output volume was obtained with dramatically reduced spatial inhomogenuity of MR signal.
    In this study, the contrast-to-noise ratio (CNR) optimation at 3 T was implemented independently to reproduce the previous results of other group. After that, the simulation of scanning parameters was done to optimize CNR of brain tissue at 1.5 T according to different encoding methods, different pulse sequences, and different reconstruction algorithms. Phantom and human experiments were carried on a 1.5 T scanner for further validation. The results of phantom experiment showed that both MP2RAGE and Ratio reconstructions can achiever better B1 homogeneity than MPRAGE, even with the vendor-equipped correction packages, SCIC and PURE. In addition, the agreement was made between simulation and in-vivo imaging that MP2RAGE provides higher CNR than Ratio when centric encoding also outduels linear encoding.
    Advisory Committee
  • Hsiao-Wen Chung - chair
  • Ming-Ting Wu - co-chair
  • Tzu-Cheng Chao - co-chair
  • Teng-Yi Huang - co-chair
  • Tzu-Chao Chuang - advisor
  • Files
  • etd-0903111-002141.pdf
  • Indicate in-campus at 0 year and off-campus access at 1 year.
    Date of Submission 2011-09-03

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