| 摘要 |
An MRI scanner and an MRI method that effectively reduce the inherent difference in timing of TE in the SIR images by using alternating polarity of the slice selective gradient pulse Gs and corresponding alternate polarity in RF phase offset in the excitation pulse. By using alternating polarity selective gradients, the refocusing gradient pulse on the Gs axis can be eliminated between the excitation pulses so that the time spacing between the multiple SIR excitation pulses is reduced, and therefore the time delay between onset of slice signal decay is reduced. This results in an earlier possible TE of the first excited slice, hence less signal decay and higher SNR, and overall the TE of different slices can be more nearly the same.
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