Method and apparatus for NMR images

Abstract

The present invention is to prevent a deterioration in NMR signals due to a slice-leaned state, in executing a pulse sequence by the spin echo method, the inclination angle (G2) of the slice gradient at the time of applying a 180 DEG RF pulse (P) is made smaller than the inclination angle (G1) of the slice gradient at the time of applying a 90 DEG RF pulse (R).

Description

technical field [0001] The invention relates to a magnetic resonance imaging method and device, more specifically, the device can eliminate the attenuation of the nuclear magnetic resonance signal caused by the slope of the slice. Background technique [0002] Figure 1 shows an example of generating a pulse sequence SQ' in a conventional echo-convolution manner. [0003] As shown in Figure 1(a), first, a 90° RF pulse R for exciting the desired slice is used to complete effective excitation; then a 180° RF pulse P for exciting the same slice is used to invert the slice; secondly, A convolute echo signal E51 as shown in Fig. 1(b) can be observed. [0004] As shown in Figure 1(c), when the above-mentioned 90° RF pulse R and 180° RF pulse P are applied, the slice gradient is increased where the magnetic field strength changes with a slope of an inclination G1 relative to the position along the slice thickness direction Bg1. [0005] As shown in Figure 2 (a), the envelope diag...

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Problems solved by technology

[0007] However, if the above-mentioned slice inclination increases, there will be a problem that no NMR signal is captured in the shaded area U between the envelope diagram and the ideal rectangle represented by the dot-dash line, resulting in the deterioration of the MRI quality. decline

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