| 摘要 |
PURPOSE: To reduce the influence of residual magnetization by impressing the gradient pulse of a positive or negative polarity on a gradient axis and, then, impressing a residual magnetization reducing pulse having the polarity and amplitude by which the residual magnetization is reduced. CONSTITUTION: A sequence storage circuit 8 operates a gradient magnetic field driving circuit 3 based on a pulse sequence in accordance with the command of a computer 7. Then the gradient pulse is impressed from the gradient magnetic field coil 1g of a magnet assembly 1. Besides, a gate modulating circuit 9 is operated, the carrier wave output signal of an RF oscillation circuit 10 is modulated, it is impressed on an RF power amplifier 4 and power is amplified. Concerning the sequence, an exciting RF pulse, a slice selecting pulse, a dephase pulse, a reverse RF pulse and the slice selecting pulse are successively impressed. Then a phase encoding pulse is impressed on a phase gradient axis. After the impression, a processing for impressing the residual magnetization reducing pulse is executed. Thus, residual magnetization is cancelled.
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