| 摘要 |
PROBLEM TO BE SOLVED: To easily and precisely measure the quantity of offset of a gradient magnetic field by eliminating the deviation of the slue rate of the gradient magnetic field and influence of the unevenness of a static magnetic field in a method of calculating the offset of the gradient magnetic field using gradient magnetic field pulses with different polarities. SOLUTION: The magnetic resonance imaging apparatus comprises a gradient magnetic field generating means for applying a gradient magnetic field including a frequency encoding gradient magnetic field to a subject, and a signal processing means for reorganizing an image of the subject by using echo signals from the subject. The gradient magnetic field generating means generates the gradient magnetic field including the offset of the gradient magnetic field, and the signal processing means has an offset deriving means for finding the offset of the gradient magnetic field by using first and second echo signals obtained by changing the polarity of the frequency encoding gradient magnetic field. The offset deriving means finds data on the phase difference based on two projection data by one-dimensionally Fourier-transforming the first and second echo signal as the projection data, finds a primary coefficient of the data on the phase difference, and finds the offset of the gradient magnetic field from the primary coefficient. COPYRIGHT: (C)2006,JPO&NCIPI
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