Abstract: In an RF excitation method and device for a magnetic resonance imaging system, the RF pulses are emitted in a STEAM sequence, the STEAM sequence including, in time order, a first 90-degree excitation pulse, a second 90-degree excitation pulse and a third 90-degree excitation pulse. Gradient pulses are activated that act in cooperation with the STEAM sequence, the gradient pulses including, in time order, a first gradient pulse, a second gradient pulse and a third gradient pulse. Each of the gradient pulses is activated simultaneously with the corresponding RF pulse. The direction of each of the gradient pulses is the vector sum of multiple gradient pulses in different directions, the directions of any two of the gradient pulses being the same and intersecting with the direction of another of the gradient pulses.

Abstract: In an RF excitation method and device for a magnetic resonance imaging system, the RF pulses are emitted in a STEAM sequence, the STEAM sequence including, in time order, a first 90-degree excitation pulse, a second 90-degree excitation pulse and a third 90-degree excitation pulse. Gradient pulses are activated that act in cooperation with the STEAM sequence, the gradient pulses including, in time order, a first gradient pulse, a second gradient pulse and a third gradient pulse. Each of the gradient pulses is activated simultaneously with the corresponding RF pulse. The direction of each of the gradient pulses is the vector sum of multiple gradient pulses in different directions, the directions of any two of the gradient pulses being the same and intersecting with the direction of another of the gradient pulses.

Abstract: In a diffusion tensor magnetic resonance imaging method for imaging a myocardial fiber structure, the diaphragm position of a subject is detected and a determination is made as to whether the diaphragm position of the subject falls into the acceptance region or not. If it does not, continue the diaphragm position of the examination subject is continued to be detected. If and when the diaphragm position is in the acceptance region, an echo planar imaging sequence with stimulated echo is executed with two electrocardiogram triggers, so as to acquire diffusion tensor image data of the myocardial fiber structure. The cardiac DTI image data thus can be obtained under free respiration of the subject, and the influence of respiratory movement is reduced and the scanning time is shortened.