Patent ID: 8890530

Claim:
A magnetic resonance imaging (MRI) apparatus comprising: gradient magnetic field coils, a static magnetic field generator, at least one radio frequency (RF) coil, at least one RF transmitter and at least one RF receiver, said components being coupled to an MRI control system configured to: acquire a magnetic resonance signal produced from an object by applying a gradient magnetic field and an RF pulse in an imaging space where the object is placed; reconstruct image data on the object based on the magnetic resonance signal; acquire an imaging region as positional information in the imaging space; and adjust a distribution of the gradient magnetic field to approximate a target distribution by transforming a waveform of the gradient magnetic field based on the positional information and a time constant of an eddy-current magnetic field to cancel at least part of the eddy-current magnetic field, the eddy-current magnetic field being induced by an eddy current caused by application of the gradient magnetic field, wherein the MRI control system is further configured (a) to calculate, for each direction of application of the gradient magnetic field, an amplitude of a component of the eddy-current magnetic field in an X-axis direction of an apparatus coordinate system, an amplitude of a component of the eddy-current magnetic field in a Y-axis direction of the apparatus coordinate system, and an amplitude of a component of the eddy-current magnetic field in a Z-axis direction of the apparatus coordinate system based on a distance between the imaging region and a magnetic field center obtained from the positional information, and (b) to adjust the distribution of the gradient magnetic field to more closely approximate the target distribution by temporally varying a value of the current supplied to the gradient magnetic field coil according to the time constant of the eddy-current magnetic field and a result of the calculations.