(A) study on fast NMR imaging modality EPIKWE

Abstract

The spin density functions of 2-Dimensional and 3-Dimensional echo planar imaging(EPI) as fast imaging modalities are formulated. For the realization of EPI, several pulse sequences including original Mansfield``s EPI are discussed, and new pulse scheme EPIKWE method which is combined with EPI and KWE is proposed. For the implementation of experimental EPIKWE imaging, cosinusoidal gradient waveform is used to overcome the gradient finite rising time effect of gradient pulse, and the obtained FID signal is interpolated toward that under switching gradient with ideal square waveform by piecewise cubic spline interpolation. The phase instability effect in full FID case and in half FID case are discussed and a new more general phase correction method is proposed. Several experimental problems are discussed. And, the generality of EPIKWE and its many application fields are discussed for further study. Particularly, the hardware and software requirement for real time imaging are discussed. The results obtained by computer simulation and under predetermined phantom imaging are presented. And, FORTRAN and Z80 Assembler programs are also presented in APPENDIX.