3-Dimensional NMR imaging methods and algorithms and their applications are studied. Among others, multislice line-integral projection method, flow velocity imaging, and parameter extraction from image data are discussed.
Line-integral projection reconstruction (LPR) in NMR imaging was found to be useful for certain cases, namely such as short $T_1$ imaging and data acquisition where compensation of phase fluctuations are needed due to the system instability. By use of encoding technique in conjunction with LPR method it is possible to excite a large volume which is found to be efficient because this leads to high SNR multislice regional imaging. Among many multislice LPR imaging methods, two basic forms using line-integral projection reconstruction are studied in this thesis, i.e., Fourier and Hadamard-like encoding methods. In addition, an optimization study of the imaging condition for a more accurate parameter extraction is studied.
Next, a new NMR flow velocity imaging method for high speed flow is proposed and discussed. In the proposed technique, a selection gradient allows us to measure high velocity flow. To find the useful phase-velocity relation of flow under the selection gradient and echo RF pulse, the Bloch equation is numerically solved. Flow effect compensation other than slice selection direction is achieved by additional flow coding gradients similar to conventional flow phase coding.
Computer simulations as well as experiments were carried out and the results are presented. Applications of the methods to the experimental NMR imaging show good agreement with predicted behavier.
3차원 NMR 영상의 새로운 펄스 기법을 제안하고 분석하였다. 특히 단면 code 화 다중단면영상법 (Slice-encoded multislice imaging method) 과 유속영상을 그 응용으로써 연구하였다.
SNR의 개선된 다단면 영상을 얻기위해 여러가지 단면 coding방법들이 분석, 비교되었다. 특히 Fourier encoded line-integral projection reconstruction (F-LPR) 과 Hadamard-like matrix encoded projection reconstruction (H-LPR) 방법들이 새로이 제안되었다.
위상-code 화 유속영상의 새로운 펄스 scheme 을 제안하고 분석 하였다. 종전의 유속영상 방법에 비해 새로이 제안된 방법은 보다 빠른 속도까지 측정이 가능했다. Selection과 reading 경사자계 영향도 고려하여 보다 정확한 유속영상을 얻고자 했다.
이 방법으로 인체의 대동맥 혈액 속도를 ECG 에 동기시켜 얻었고 유체역학에서의 응용으로 유체 통로에서의 유속을 구하여 Laser Dopper Velocimetry로 측정한 결과와 거의 일치하였다.
