Method and system for correcting errors in MR images due to regions of gradient non-uniformity for parametric imaging such as quantitative flow analysis
First Claim
1. A method of correcting systematic errors occurring due to magnetic gradient non-uniformity in phase contrast MR images for quantitative flow analysis comprising the steps ofgenerating a gradient non-uniformity error map for an MR image scan that includes a representation of magnetic gradient strength non-uniformity as a function of distance;
- acquiring at least two MR data sets having flow sensitive gradients containing systematic errors due to magnetic gradient non-uniformity;
calculating a phase difference image to determine a measured velocity image; and
calculating a corrected velocity image using the measured velocity image and the gradient non-uniformity error map.
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Abstract
A system and method for correcting systematic errors that occur in MR images due to magnetic gradient non-uniformity is disclosed for use with parametric analysis. A GradWarp geometric correction operation is applied in reconstructing quantitative parametric analysis images in regions of gradient non-uniformity. The method includes generating an error map of magnetic gradient strength as a function of distance for an MR image scan and acquiring MR data that contain such systematic errors. The method next includes either calculating a measured diffusion image, a phase difference image, or similar image, based on the acquired MR data, and then calculating a corrected parametric image using the error map and the measured diffusion image, the phase difference image, or other similar parametric image. The method is incorporated into a system having a computer programmed to perform the aforementioned steps and functions.
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Citations
27 Claims
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1. A method of correcting systematic errors occurring due to magnetic gradient non-uniformity in phase contrast MR images for quantitative flow analysis comprising the steps of
generating a gradient non-uniformity error map for an MR image scan that includes a representation of magnetic gradient strength non-uniformity as a function of distance; -
acquiring at least two MR data sets having flow sensitive gradients containing systematic errors due to magnetic gradient non-uniformity; calculating a phase difference image to determine a measured velocity image; and calculating a corrected velocity image using the measured velocity image and the gradient non-uniformity error map. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for correcting systematic errors occurring due to magnetic gradient non-uniformity in phase contrast MR images for quantitative flow analysis comprising:
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means for acquiring at least two MR data sets having flow sensitive gradients containing systematic errors due to magnetic gradient iron-uniformity and generating a phase image therefrom for each acquired MR data set; means for generating a gradient non-uniformity error for an MR image scan, that includes a representation of magnetic gradient strength non-uniformity as a function of distance, calculating a phase difference image from each phase image generated to determine a measured velocity image, calculating a corrected velocity image using the measured velocity image and the gradient non-uniformity error map. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A system to correct systematic errors occurring due to magnetic gradient non-uniformity in phase contrast MR images for quantitative flow analysis comprising a processor programmed to:
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generate a gradient non-uniformity error map for an MR image scan that includes a representation of magnetic gradient strength non-uniformity as a function of distance; acquire at least two NM data sets having flow sensitive gradients containing a systematic error due to magnetic gradient non-uniformity; calculate a phase difference image to determine a measured velocity image; and calculate a corrected velocity image using the measured velocity image and the gradient non-uniformity error map. - View Dependent Claims (15, 16, 17, 18)
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19. A method of correcting systematic errors occurring due to magnetic gradient non-uniformity in diffusion MR images comprising the steps of
generating at least one gradient non-uniformity error map for an MR image scan that includes a representation of magnetic gradient strength non-uniformity as a function of distance; -
acquiring at least one MR data set with diffusion sensitizing gradients containing systematic errors due to magnetic gradient non-uniformity;
calculating a measured diffusion image based on the acquired MR data set, andcalculating a corrected diffusion image using the measured diffusion image and at least one gradient non-uniformity error map. - View Dependent Claims (20, 21)
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22. A system for correcting systematic errors occurring due to magnetic gradient non-uniformity in diffusion MR images comprising:
- means for acquiring at least one MR data set with diffusion sensitizing gradients that contain systematic errors due to magnetic gradient non-uniformity;
means for generating at least one gradient non-uniformity error map for an MR image scan, that includes a representation of magnetic gradient strength non-uniformity as a function of distance, calculating a measured diffusion image based on the acquired MR data sets, and calculating a corrected diffusion image using the measured diffusion image and at least one gradient non-uniformity error map. - View Dependent Claims (23, 24)
- means for acquiring at least one MR data set with diffusion sensitizing gradients that contain systematic errors due to magnetic gradient non-uniformity;
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25. A system to correct systematic errors occurring due to magnetic gradient non-uniformity in diffusion MR images comprising a processor programmed to:
- generate at least one gradient non-uniformity error map for an MR image scan that includes a representation of magnetic gradient strength non-uniformity as a function of distance;
acquire at least one MR data set with diffusion sensitizing gradients that contain systematic errors due to magnetic gradient non uniformity; calculate a measured diffusion image based on the at least one MR data set acquired; and calculate a corrected diffusion image using the measured diffusion image and the at least one gradient non-uniformity error map. - View Dependent Claims (26, 27)
- generate at least one gradient non-uniformity error map for an MR image scan that includes a representation of magnetic gradient strength non-uniformity as a function of distance;
Specification