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Methods for optimal gradient design and fast generic waveform switching

  • US 10,641,857 B2
  • Filed: 03/06/2015
  • Issued: 05/05/2020
  • Est. Priority Date: 09/07/2012
  • Status: Active Grant
First Claim
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1. A method of generating a multi-dimensional gradient waveform for use in a magnetic resonance imaging (MRI) device coupled to a computer system, the method comprising:

  • (a) providing a set of design constraints for the multi-dimensional gradient waveform along each dimension of the multi-dimensional gradient waveform, wherein the set of design constraints comprise a gradient start amplitude and a gradient end amplitude;

    (b) providing a set of hardware limitations for maximum gradients achievable by the MRI device, the set of hardware limitations comprising a maximum gradient slew-rate on each physical axis of the MRI device and a maximum gradient amplitude on each physical axis;

    (c) providing, a set of regulatory limitations for maximum gradient fields that may be safely applied to a scan subject, the set of regulatory limitations comprising a maximum safe rate of change of a magnetic field of the MRI device for the scan subject;

    (d) applying, with the aid of the computer processor, one or more geometric transformations to the set of design constraints, the set of hardware limitations, and the set of regulatory limitations, thereby placing the design constraints, the hardware limitations, and the regulatory limitations in a geometrically transformed coordinate space;

    (e) calculating, with the aid of the computer processor, a gradient waveform for each gradient dimension that simultaneously satisfies all of the design constraints, hardware limitations, and regulatory limitations in the geometrically transformed coordinate space;

    (f) determining, with the aid of the computer processor, whether each dimension of the gradient waveform meets an equal length condition of having the same time length as all other dimensions of the gradient waveform;

    (g) repeating steps (d), (e), and (f) with different geometric transformations at each iteration until the equal length condition of step (f) is satisfied, thereby generating the multi-dimensional gradient waveform; and

    (h) generating a magnetic field gradient pulse, with the MRI device, according to criteria of the multi-dimensional gradient waveform of step (g).

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