Patent ID: 7355405

Claim:
A magnetic resonance imaging system, comprising: a means for generating a static magnetic field; a radiofrequency magnetic field generation means for generating a radiofrequency magnetic field that is applied to a subject placed in the static magnetic field; a magnetic field gradient generation means for generating a magnetic field gradient that is applied to the subject; a measurement means for measuring a magnetic resonance signal generated from the subject; an arithmetic means for computing the magnetic resonance signal; a storage means in which the magnetic resonance signal and the results of computation performed by the arithmetic means are stored; and a sequence control means for controlling the actions of the respective pieces of means, wherein: the sequence control means extends control for irradiating the radiofrequency magnetic field to the subject at least once, measuring the magnetic resonance signal, which is generated after the irradiation of the radiofrequency magnetic field, with the applied strength of the magnetic field gradient nearly nullified, calculating information on a magnetic resonance spectrum using the measured magnetic resonance signal, and thus measuring the magnetic resonance spectrum; and when the sequence control means repeats the measurement of the magnetic resonance signal a plurality of times, the sequence control means extends at least one of: (1) control for performing a pre-scan, which is intended to measure the position of a peak of a water signal and a signal phase, at least once during the repetition of the measurement of the magnetic resonance signal; (2) control for detecting a magnitude of deviation, by which the water-signal peak position deviates from a predetermined reference position, using a magnetic resonance spectrum resulting from Fourier transform of the magnetic resonance signal obtained during the pre-scan; (3) control for calculating the signal phase value at the water-signal peak position detected as mentioned in (2); and (4) control for designating a reception-initiating phase value, which is used to measure the magnetic resonance signal during the spectrum measurement to be performed succeedingly to the pre-scan, on the basis of the signal phase value calculated as mentioned in (3), and for shifting the magnetic resonance spectrum, which results from Fourier transform of the magnetic resonance signal obtained during the spectrum measurement performed succeedingly to the pre-scan, by the magnitude of deviation on the basis of the water-signal peak position detected as mentioned in (2).