| 摘要 |
An object is to correct a magnetic field caused by an eddy current, which is generated due to application of a gradient magnetic field, not only in the application direction of the gradient magnetic field but also in a direction different from the application direction of the gradient magnetic field. In the present invention, in order to achieve this object, a compensation magnetic field which compensates for an eddy current magnetic field generated in each of an application direction of a test gradient magnetic field and a direction different from the application direction in each direction is calculated using the test gradient magnetic field. When generating an arbitrary gradient magnetic field, a compensation magnetic field which compensates for an eddy current magnetic field according to application of an arbitrary gradient magnetic field on the basis of the measured eddy current magnetic field in each direction is generated together with the arbitrary gradient magnetic field. |
| 主权项 |
1. A magnetic resonance imaging apparatus comprising:
a gradient magnetic field generating unit that generates an arbitrary gradient magnetic field; an eddy current magnetic field measuring unit that measures an eddy current magnetic field based on an eddy current, which is generated according to application of a test gradient magnetic field, through a phase of an image; and a compensation magnetic field calculating unit that calculates a compensation magnetic field, which is for compensating for an eddy current magnetic field according to application of the arbitrary gradient magnetic field, on the basis of the measured eddy current magnetic field, wherein the gradient magnetic field generating unit generates the compensation magnetic field in addition to the arbitrary gradient magnetic field, wherein the eddy current magnetic field measuring unit reconstructs three-dimensional images from echo signals measured by changing a polarity of the test gradient magnetic field, acquires a three-dimensional phase difference image by calculating a difference between phase images of two three-dimensional images, and measures the eddy current magnetic field generated in each direction amongst an application direction of the test gradient magnetic field and another direction which is different from the application direction, on the basis of a difference between phases in two points or regions in each of said application direction and said another direction, in a pair of planes in the three-dimensional phase difference image, the compensation magnetic field calculating unit calculates the compensation magnetic field, which compensates for the eddy current magnetic field according to the application of the arbitrary gradient magnetic field, and distributes the calculated compensation magnetic field in each application direction of the gradient magnetic field, on the basis of the measured eddy current magnetic field in said each direction, and the gradient magnetic field generating unit generates the calculated compensation magnetic field distributed in said each application direction of the gradient magnetic field, together with the arbitrary gradient magnetic field. |
