Image correction during magnetic resonance dependent on the reception profile of the reception antenna
In a method and apparatus for correcting image data acquired by an image data acquisition scanner of a magnetic resonance system, a reception profile of a reception antenna of the magnetic resonance scanner is determined. A correction function is determined by which an asymmetry of the reception profile with respect to a symmetry plane is corrected. Furthermore, image data are received and corrected by multiplying the intensity values of the image data with the determined correction function.
1. A method for correcting magnetic resonance image data, comprising:
providing a computer with an electronic designation of a representative reception profile that represents a reception profile of a reception antenna arrangement of a magnetic resonance scanner;
in said computer, determining a correction function that corrects an asymmetry of said representative reception profile with respect to a symmetry plane of an examination subject from whom magnetic resonance raw data will be acquired with said magnetic resonance scanner;
operating the magnetic resonance scanner to acquire magnetic resonance raw data from the examination subject;
in said computer, applying a reconstruction algorithm to said raw data to reconstruct image data therefrom, said image data comprising intensity values that are distorted due to said asymmetry of the representative reception profile with respect to said symmetry plane of the examination subject; and
in said computer, specifically correcting said distortion of said intensity values of said image data caused by the representative reception profile being asymmetric with respect to the symmetry plane of the examination subject, by multiplying the intensity values of the image data with said correction function, and thereby obtaining corrected image data, and making the corrected image data available from the computer in electronic form as a data file.
2. A method as claimed in claim 1 wherein said reception antenna arrangement comprises a volume coil and a local coil, and wherein said representative reception profile is a reception profile of said volume coil, and comprising acquiring said raw data from the examination subject with said local coil, and normalizing a reception profile of said local coil to the reception profile of said volume coil.
3. A method as claimed in claim 1 wherein said symmetry plane is at least one plane in a Cartesian coordinate system, said at least one plane being selected from the group consisting of the yz plane, the xy plane and the xz plane.
4. A method as claimed in claim 1 comprising automatically determining said symmetry plane in said computer by applying a pattern recognition algorithm to identify a shape of a selected body part of the examination subject and determining said symmetry plane from the shape of the body part.
5. A method as claimed in claim 4 comprising, dependent on the identified shape of the body part, automatically controlling said magnetic resonance scanner from said computer to automatically center, with respect to the body part, an examination volume from which said raw data are acquired.
6. A method as claimed in claim 1 wherein said correction function is the square root of a quotient of the representative reception profile mirrored at said symmetry plane, and said representative reception profile.
7. A method as claimed in claim 1 wherein said magnetic resonance scanner comprises a transmit antenna, and determining said representative reception profile of said reception antenna arrangement by mirroring a transmit profile of said transmit antenna with respect to a symmetry plane of the transmit antenna.
8. A method as claimed in claim 7 wherein said transmit antenna radiates a B1 field when said magnetic resonance scanner is operated to acquire said raw data, and comprising determining said transmit profile using a B1 mapping method.
9. A method as claimed in claim 7 wherein said transmit profile exhibits an inhomogeneity, and, in said computer, correcting said image data to correct a further distortion in said image data that results from said inhomogeneity of the transmit profile, in addition to correcting the distortion that occurs due to said asymmetry.
10. A method as claimed in claim 9 comprising correcting said further distortion in said image data by generating a further correction function that corrects for said inhomogeneity, and multiplying the intensity values of the image data with said further correction function.
11. A method as claimed in claim 1 comprising operating said magnetic resonance scanner to acquire said raw data from the examination subject by executing a pulse sequence that comprises B1 insensitive RF pulses.
12. An image correction device for correcting magnetic resonance image data, comprising:
a computer comprising an input interface that receives an electronic designation of a representative reception profile that represents a reception profile of a reception antenna arrangement of a magnetic resonance scanner;
said computer being configured to determine a correction function that corrects an asymmetry of said representative reception profile with respect to a symmetry plane of an examination subject from whom magnetic resonance raw data will be acquired with said magnetic resonance scanner;
said computer being configured to operate the magnetic resonance scanner to acquire magnetic resonance raw data from the examination subject;
said computer being configured to apply a reconstruction algorithm to said raw data to reconstruct image data therefrom, said image data comprising intensity values that are distorted due to said asymmetry of the representative reception profile with respect to said symmetry plane of the examination subject; and
said computer being configured to specifically correct said distortion of said intensity values of said image data caused by the representative reception profile being asymmetric with respect to the symmetry plane of the examination subject, by multiplying the intensity values of the image data with said correction function, and thereby obtaining corrected image data, and to make the corrected image data available from the computer in electronic form as a data file.
13. A magnetic resonance apparatus comprising:
a magnetic resonance scanner comprising a reception antenna arrangement;
a computer provided with an electronic designation of a representative reception profile that represents a reception profile of a reception antenna arrangement of a magnetic resonance scanner;
said computer being configured to determine a correction function that corrects an asymmetry of said representative reception profile with respect to a symmetry plane of an examination subject from whom magnetic resonance raw data will be acquired with said magnetic resonance scanner;
said computer being configured to operate the magnetic resonance scanner to acquire magnetic resonance raw data from the examination subject;
said computer being configured to apply a reconstruction algorithm to said raw data to reconstruct image data therefrom, said image data comprising intensity values that are distorted due to said asymmetry of the representative reception profile with respect to said symmetry plane of the examination subject; and
said computer being configured to specifically correct said distortion of said intensity values of said image data caused by the representative reception profile being asymmetric with respect to the symmetry plane of the examination subject, by multiplying the intensity values of the image data with said correction function, and thereby obtaining corrected image data, and to make the corrected image data available from the computer in electronic form as a data file.
14. A non-transitory, computer-readable data storage medium encoded with programming instructions, said data storage medium being loaded into a control computer of a magnetic resonance apparatus that comprises a magnetic resonance scanner with a reception coil arrangement, said programming instructions causing said control computer to:
receive an electronic designation of a representative reception profile that represents a reception profile of a reception antenna arrangement of a magnetic resonance scanner;
determine a correction function that corrects an asymmetry of said representative reception profile with respect to a symmetry plane of an examination subject from whom magnetic resonance raw data will be acquired with said magnetic resonance scanner;
operate the magnetic resonance scanner to acquire magnetic resonance raw data from the examination subject;
apply a reconstruction algorithm to said raw data to reconstruct image data therefrom, said image data comprising intensity values that are distorted due to said asymmetry of the representative reception profile with respect to said symmetry plane of the examination subject; and
specifically correct said distortion of said intensity values of said image data caused by the representative reception profile being asymmetric with respect to the symmetry plane of the examination subject, by multiplying the intensity values of the image data with said correction function, and thereby obtaining corrected image data, and to make the corrected image data available from the computer in electronic form as a data file.