MRI image quality improvement using matrix regularization
AssigneeGE Medical Systems Global Technologies Company LLC
InventorKevin F. King
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Abstract
A method and apparatus for increasing the signal-to-noise ratio in a magnetic resonance image generated with a system including at least two receiver coils where the data acquisition period is reduced by increasing the space between k-space raster data rows such that image wrapping occurs and an unwrapping algorithm is required, the method including identifying a sensitivities matrix corresponding to the receiver coils, acquiring NMR signals and converting those signals to image pixel intensities, defining a correction matrix, altering the sensitivities matrix as a function of the correction matrix, combining the altered sensitivities matrix and the intensity matrix to generate an estimated spin density matrix and using a spin density matrix to generate the final image.
Claims19
A method for use with a multiple receiver coil magnetic resonance imaging (MRI) system used to generate a two dimensional slice image through an object where the field of view during data acquisition is smaller than the object cross section to be imaged such that upon transforming acquired k space data into image data, the resulting wrapped images include wrapped image sections where wrapped pixel intensities include intensity from each of a properly located pixel and at least one wrapped pixel, each receiver coil receiving an MRI signal from each location within the object cross section and having a coil specific sensitivity that indicates how the coil reacts to signals from the different points within the slice, the method for increasing the signal to noise ratio of image pixels upon unwrapping of wrapped image sections, the method comprising the steps of, for each pixel in the wrapped images:
- identifying the coil sensitivities for each coil in the multiple coil system and arranging the coil sensitivities to form a sensitivities matrix S for the pixel;
- arranging the intensities from each coil corresponding to the image pixel into an intensity matrix;
- generating a modified coil sensitivities matrix S′ by modifying sensitivities matrix S;
- inverting the modified sensitivities matrix;
- multiplying the inverted matrix by the intensity matrix to generate a spin densities matrix including unwrapped pixel spin densities corresponding to the pixel;
- and
- using the spin densities matrix to generate a final image.
An apparatus for use with a multiple receiver coil magnetic resonance imaging (MRI) system used to generate a two dimensional slice image through an object where the field of view during data acquisition is smaller than the object cross section to be imaged such that upon transforming acquired k space data into image data, the resulting wrapped image includes wrapped image sections where wrapped pixel intensities include intensity from each of a properly located pixel and at least one wrapped pixel, each receiver coil receiving an MRI signal from each location within the object cross section and having a coil specific sensitivity that indicates how the coil reacts to signals from the different points within the slice, the apparatus for increasing the signal to noise ratio of final image pixels upon unwrapping of at least one wrapped pixel, the apparatus comprising, for each pixel in a wrapped image:
- means for identifying the coil sensitivities for each coil in the multiple coil system and arranging the coil sensitivities to form a sensitivities matrix S;
- means for arranging the intensities corresponding to the pixel into an intensity matrix;
- means for generating a modified coil sensitivities matrix S′ by modifying sensitivities matrix S;
- means for inverting the modified sensitivities matrix;
- means for multiplying the inverted matrix by the intensity matrix to generate a spin densities matrix for final image pixels corresponding to the pixel;
- and
- using the spin densities matrix to generate the final image.
An apparatus for use with a multiple receiver coil magnetic resonance imaging (MRI) system used to generate a two dimensional slice image through an object where the field of view during data acquisition is smaller than the object cross section to be imaged such that upon transforming acquired k space data into image data, the resulting wrapped image includes wrapped image sections where wrapped pixel intensities include intensity from each of a properly located pixel and at least one wrapped pixel, each receiver coil receiving an MRI signal from each location within the object cross section and having a coil specific sensitivity that indicates how the coil reacts to signals from the different points within the slice, the method for increasing the signal to noise ratio of image sections upon unwrapping of the wrapped image sections, the method comprising, for each pixel in a wrapped image:
- identifying the coil sensitivities for each coil in the multiple coil system and arranging the coil sensitivities to form a sensitivities matrix S;
- arranging the intensities corresponding to the wrapped image pixel from each coil into an intensity matrix;
- generating a modified coil sensitivities matrix S′ by modifying sensitivities matrix S;
- inverting the modified sensitivities matrix;
- multiplying the inverted matrix by the intensity matrix to generate a spin densities matrix for final image pixels corresponding to the wrapped image pixel;
- and
- using the spin densities matrix to generate the MR image.
Dependencies are inferred from the claim text.