서지주요정보
(A) study of steady-state free precession in NMR and its application to imaging = 핵자기 공명 영상에서 SSFP 스핀 시스템과 그의 영상에의 응용에 관한 연구
서명 / 저자 (A) study of steady-state free precession in NMR and its application to imaging = 핵자기 공명 영상에서 SSFP 스핀 시스템과 그의 영상에의 응용에 관한 연구 / Dae-Jin Kim.
저자명 Kim, Dae-Jin ; 김대진
발행사항 [대전 : 한국과학기술원, 1991].
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소장정보

등록번호

8002327

소장위치/청구기호

학술문화관(문화관) 보존서고

DEE 9127

SMS전송

도서상태

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반납예정일

초록정보

Since steady-state free precession (SSFP) was first described by Carr in 1958, several groups have analyzed the behavior of the magnetization and the resulting image contrasts. Major interests have been, however, the two components of SSFP signals : namely, the signals obtained just after and before the RF pulses which are known as FISP and CE-FAST, respectively. In practice, simultaneous acquisition of above two signal has become more popular since each of these signals usually exhibits different contrasts. Furthermore, by positioning the two signals exactly to the same time, and inhomogeneity map can also ne measured form the interference pattern of the two signals. In the steady-state free precession with an applied linear gradient, the transverse magnetizations are periodically distributed. Fourier analysis of this periodic distribution leads to the understanding of many interesting phenomena in SSFP. It is found that there are many other higher order echoes in SSFP in addition to the previously known echoes. In this thesis, a generalized equation of the transverse magnetization of SSFP are derived and the echo time independent term of the transverse magnetization are expanded with Fourier series. By this Fourier expansion, the higher order echoes including the two previously known FISP and CE-FAST are understood and explained. The theory of these higher order echoes is studied in detail, and computer simulations and experiments are preformed to confirm the validity of this analysis by using KAIS 2.0T superconducting NMR system. For the portential application of the higher order echoes, a motion insensitive imaging technique is developed. Even if SSFP imaging technique have very high signal-to-noise ratio for the tissues with long T2, it has a disadvantage of their great sensitivity to motion. The signals from moving spins are strongly sttenuated and motion artifacts are observed because a steady state cannot be attained for those spins that move along a magnetic field gradient. To avoid this sensitivity to motion, i.e., to attain a steady state for moving spins, the time integral of the magnetic field gradients must vanish over a repetition time. This condition, however, causes interference pattern to appear in the image because all the higher order echoes are coincided. This superimposed higher order echoes are separated by using RF phase cycling technique, and motion insensitive images are obtained. In the appendix, a correction technique of the total magnetic inhomogeneity effects including the localized object induced inhomogeneities such as chemical shift and susceptibility is included and its experimental results are given.

서지기타정보

서지기타정보
청구기호 {DEE 9127
형태사항 vii, 109 p. : 삽도 ; 26 cm
언어 영어
일반주기 Appendix : Total inhomogeneity correction including chemical shifts and susceptibility by view angle tilting
저자명의 한글표기 : 김대진
지도교수의 영문표기 : Zang-Hee Cho
지도교수의 한글표기 : 조장희
학위논문 학위논문(박사) - 한국과학기술원 : 전기 및 전자공학과,
서지주기 Reference : p. 62-66
주제 Precession
Magnetization
Fourier series
NMR 이미징 --과학기술용어시소러스
Fourier 급수 --과학기술용어시소러스
자화 --과학기술용어시소러스
영상 조정 장치 --과학기술용어시소러스
Magnetic resonance imaging
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