| 摘要 |
PROBLEM TO BE SOLVED: To prevent the degradation of image quality due to eddy currents and residual magnetization caused by a phase encode gradient. SOLUTION: In an MRI system, an excitation RF (radio frequency) pulse is transmitted, then a reversal RF pulse is transmitted, a phase encode gradient is then applied on a warp axis, and finally an NMR signal is received while applying a read gradient on a read axis. After the processes from transmitting the reverse RF pulse to receiving an NMR signal are repeated M times, a killer gradient is applied. The processes from transmitting the excitation RF pulse to applying the killer gradient are repeated N times. Then NMR signals processed by different phase encodes of (M×N) times are collected. The polarity of the killer gradient is switched so as to be identical with the polarity of the sum of phase encode gradients of M times to be applied when processes from transmitting the reverse RF pulse to receiving the NMR signal are repeated M times. COPYRIGHT: (C)2004,JPO
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