PROBLEM TO BE SOLVED: To provide an MRI apparatus which can be applied to various sequences and can efficiently suppress unnecessary NMR signals generated by prepulses.SOLUTION: The MRI apparatus comprises: static magnetic field generation means for generating a uniform static magnetic field in a space in which a subject is to be received gradient magnetic field generation means for generating a gradient magnetic field superimposedly on the static magnetic field high-frequency magnetic field generation means for generating a high-frequency magnetic field to irradiate the subject with excitation pulses control means for application of the excitation pulses and the gradient magnetic field according to a designated pulse sequence signal detection means for detecting echo signals emitted from the subject and signal processing means for converting the echo signals into an image. The control means applies prepulses before the excitation pulses and dynamically controls crusher gradient magnetic field pulses to be applied according to the intensity, polarity, or device characteristics of the gradient magnetic field to phase-disperse unnecessary transverse magnetization generated by the prepulses.SELECTED DRAWING: Figure 4COPYRIGHT: (C)2017,JPO&INPIT【課題】様々なシーケンスに適用することができ、且つプリパルスで発生した不要なNMR信号を効率良く抑制する。【解決手段】MRIは、被検体を収容する空間に均一な静磁場を発生させる静磁場発生手段と、前記静磁場に重畳して傾斜磁場を発生させる傾斜磁場発生手段と、前記被検体に励起パルスを照射するための高周波磁場を発生させる高周波磁場発生手段と、所定のパルスシーケンスにしたがって前記励起パルス及び前記傾斜磁場を印加する制御手段と、前記被検体から放出されるエコー信号を検出する信号検出手段と、前記エコー信号を画像化する信号処理手段と、を有し、前記制御手段は、前記励起パルスの前にプリパルスを印加し、前記プリパルスによって発生した不要な横磁化を位相分散させるために、前記傾斜磁場の強度、極性又は装置特性に対応して印加するクラッシャー傾斜磁場パルスを動的に制御する。【選択図】図4
