(A) study on perfusion and diffusion procrssrs by NMR imaging techniques핵자기 공명 영상기법을 이용한모세관류 및 확산에 관한 연구

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It this thesis, two types of spin motions, i.e., perfusion and diffusion, are studied by NMR imaging techniques. Initially, perfusion in biological tissues via capillaries is modeled as an ensemble of linear flow each moving in straight coherently with constant velocities, but the orientations are assumed to be distributed uniformly in all directions. Based on this model, effects of random directional flow on the reconstructed NMR image are investigated. As a result of perfusion, the aggregated signal intensity is reduced compared to that of the stationary spins, however, the phase is not affected by the isotropic random motion. The amount of attenuation is formulated analytically in a form of velocity distribution function. An experimental pulse scheme related to the above theoretical study to visualize the amount of capillary flow or perfusion related activities as a function of a spatial position is proposed. Some results with phantom containing random directional flow as well as human volunteers are presented. In the diffusion experiment, an optimized pulse sequence to maximize Signal-to-Noise Ratio (SNR) in the final diffusion map is derived and experimentally confirmed. The technique varies the duration of the readout gradient to make different attenuations in a set of diffusion affected images. One important feature of the current technique is the employment of the low gradient fields easily available in the conventional whole body NMR imaging system. The experimental measurements of the diffusion coefficient for several materials by the proposed scheme agree well with others results. Some preclinical applications of the diffusion map have also attempted to a number of human volunteers. Finally, a new phase correction method is proposed, which is essential to most of the phase-involved imaging techniques including coherent bulk flow imaging, quadrature spectroscopic imaging, and inversion recovery imaging. The proposed scheme consists of first and zer...
Advisors
Cho, Zang-Heeresearcher조장희researcher
Description
한국과학기술원 : 전기 및 전자공학과,
Publisher
한국과학기술원
Issue Date
1986
Identifier
60970/325007 / 000815157
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 전기 및 전자공학과, 1986.8, [ vi, 98 p. ]

URI
http://hdl.handle.net/10203/35763
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=60970&flag=dissertation
Appears in Collection
EE-Theses_Ph.D.(박사논문)
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