Motion artifact suppression technique of magnetic resonance imaging

In a magnetic resonance image generating sequence, which includes at least the application of a radio frequency resonance excitation pulse, a slice select gradient pulse, and a read gradient pulse, the improvement comprising:

• in the direction of at least one of the slice select and read gradients, applying at least one motion desensitization gradient pulse between the resonance excitation pulse and the read gradient pulse, the amplitude and duration of the motion desensitization pulse being selected such that the sum of at least one of the zeroth, first, second, and third moment in time of the phase of the gradient pulses along the selected one of the slice select and read gradient directions is set equal to a preselected value;
• determining the appropriate duration and amplitudes of the motion desensitization gradient pulses, the amplitude and duration determining steps including:
• selecting beginning and ending times for each gradient pulse, the number of motion desensitization gradient pulses being the same as the number of moments which are to be set to preselected values;
• along each of the slice select and read directions, setting the corresponding each term of the power series expansion:
• ##EQU9## to one of the preselected values and solving for the amplitudes of the motion desensitization gradients, .gamma. is the gyromagnetic ratio, G(t) is the gradient at time t, and x.sub.o.sup.(j) is the jth differential of position x at time 0.

An apparatus for generating motion desensitized magnetic resonance images, the apparatus comprising:

• main magnetic field means for generating a generally uniform magnetic field through an image region;
• a radio frequency pulse means for selectively applying radio frequency pulses to the image region, at least some of the radio frequency pulses being configured for exciting magnetic resonance of selected dipoles in the image region;
• a slice selection gradient control means for selectively applying magnetic field gradient pulse in a slice select direction across the image region;
• read gradient control means for selectively applying magnetic field gradient pulses across the image region in a read direction;
• a phase encode gradient control means for selectively applying magnetic field gradients in a phase encode direction across the image region;
• an imaging pulse sequence and motion desensitization memory means for storing amplitude and relative timing information for each of a plurality of selectable imaging sequences including RF, slice select gradient, read gradient, and phase encode gradient pulses, and motion desensitization magnetic field gradient pulses to be applied in each of the slice select and read gradient directions;
• a pulse sequence format means operatively connected with the imaging pulse sequence and motion desensitization pulse memory means and with the radio frequency pulse means, the slice select gradient control means, the read gradient control means, the phase encode gradient control means for causing the radio frequency pulse control means, the slice select gradient control means, the read gradient control means, and the phase encode gradient control means to apply the selected sequence of imaging and motion desensitization pulses to the image region;
• a radio frequency receiving means for receiving radio frequency magnetic resonance signals from the image region;
• and,
• image reconstruction means for forming an image representation from the received magnetic resonance signals.