| 摘要 |
In an SPI method for the n-dimensional NMR imaging of materials with short T2-relaxation times, for example cartilage or bones, only one single measurement point in k-space is recorded from the phase encoded FID signal following each RF excitation pulse. A pseudo spin echo (4) is derived from the extracted k-space points which has essentially the same information content as a conventional spin echo signal. In order to prevent excessive noise development when switching the gradients, the gradients are also applied during the waiting time between the recording of individual points, and the stepwise change of the gradient fields from one point to the next is done in such a fashion that at least one of the gradient fields is not fully switched-off between two individual points rather only changed, in each case, by an increment value which is very small compared to the maximum value of the corresponding gradient fields, whereby the size of the increment value corresponds to one to z-times the separation between two neighboring points in k-space, and preferentially z<5.
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