| 摘要 |
Spatially discriminated information is obtained by appropriately processing data which are generated with the aid of a set of pulsed nuclear magnetic resonance operations carried out by means of a magnetic field having a linear gradient whose magnitude varies for each operation. In order to obtain a two-dimensional image of the spin density distribution, coil sets (5 and 6) are used to generate magnetic field components which yield X- and Y-gradients, the magnitude of the former being varied in steps while that of the latter remains unaltered. For each value of the X-gradient, the sample (1) is irradiated with pulsed high-frequency energy, the resultant nuclear magnetic resonance signals being detected with the aid of phase-sensitive detectors (19 and 20), whose output signals are regularly sampled by analog/digital converters (25 and 26). In processing the complete sampled data using a computer (12), both a Fourier transformation with respect to the magnitude of the X-gradient and a Fourier transformation with respect to time are carried out. If there is a requirement to obtain cross-sectional images, a third set of coils (7) is used in order to generate a component which yields an alternating Z-gradient and the irradiation is carried out with the aid of a train of pulses. <IMAGE>
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