Magnetic resonance field map estimation for species separation
AssigneeThe Board of Trustees of the Leland Stanford Junior University
InventorWenmiao Lu
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Abstract
A method for mapping field inhomogeneity for forming a magnetic resonance image is provided. A magnetic resonance excitation is applied. A plurality of k-space echoes signals is acquired. A periodic cost function is calculated from the acquired plurality of k-space echo signals. A period of the calculated periodic cost function is divided into multiple regions. A search algorithm is used to locate a local minimum in each region. Located local minimums are chosen to provide global smoothness.
Claims18
A method for mapping field inhomogeneity for forming a magnetic resonance image, comprising:
- a) applying a magnetic resonance excitation;
- b) acquiring a plurality of k-space echoes signals;
- c) calculating a periodic cost function from the acquired plurality of k-space echo signals;
- d) dividing a period of the calculated periodic cost function into multiple regions;
- e) using a search algorithm to locate a local minimum in each region of the multiple regions of the divided period;
- f) choosing located local minimums to provide global smoothness;
- and
- g) generating a field map by progressively growing the field map from the local minimums.
A non-transitory computer implemented method for generating magnetic resonance images, comprising:
- generating an inhomogeneity field map, comprising:
- a) applying a magnetic resonance excitation;
- b) acquiring a plurality of k-space echoes signals;
- c) calculating a periodic cost function from the acquired plurality of k-space echo signals;
- d) dividing a period of the calculated periodic cost function into multiple regions;
- e) using a search algorithm to locate a local minimum in each region of the multiple regions of the divided period;
- f) choosing located local minimums to provide global smoothness;
- g) generating a field map by progressively growing the field map from the local minimums;
- h) using the field map to provide a corrected magnetic resonance image with species separation;
- and
- i) using the field map to generate a magnetic resonance image.
A magnetic resonance imaging apparatus, comprising:
- a magnetic resonance imaging excitation and detection system;
- and
- a controller electrically connected to the magnetic resonance imaging excitation and detection system, comprising:
- a display;
- at least one processor;
- and
- non-transitory computer readable media, comprising:
- computer readable code for generating an inhomogeneity field map, comprising:
- a) computer readable coded for applying a magnetic resonance excitation;
- b) computer readable code for acquiring a plurality of k-space echoes signals;
- c) computer readable code for calculating a periodic cost function from the acquired plurality of k-space echo signals;
- d) computer readable code for dividing a period of the calculated periodic cost function into multiple regions;
- e) computer readable code for using a search algorithm to locate a local minimum in each region of the multiple regions of the divided period;
- f) computer readable code for choosing located local minimums to provide global smoothness;
- and
- g) computer readable code for generating a field map by progressively growing the field map from the local minimums;
- computer readable code for using the field map to provide a corrected magnetic resonance image with species separation;
- and
- computer readable code for displaying the magnetic resonance image on the display.
Dependencies are inferred from the claim text.