Method and apparatus to determine complex sensitivity factors of RF reception coils for magnetic resonance spectroscopy

1. A method for generating a magnetic resonance (MR) spectroscopy data record for a volume of interest of an examination subject comprising:

(a) operating an MR scanner, comprising at least two radio-frequency (RF) reception coils, from a control computer while an examination subject is situated in the MR scanner, to acquire respective free induction decays (FID) signals, representing MR spectroscopy data, from a volume of interest of the examination subject simultaneously with each of said RF reception coils;

(b) in said control computer, selecting one of said RF reception coils as a reference coil and designating the respective FID signal thereof as a reference signal;

(c) in said control computer, for each RF reception coil other than said reference coil, determining a complex sensitivity factor by minimizing a difference between a number of data points of the respective FID signal thereof, weighted with said complex sensitivity factor, and corresponding data points of the FID signal of the reference coil;

(d) in said control computer, combining MR spectroscopy data acquired from said volume of interest simultaneously with said RF reception coils, weighted with the respective complex sensitivity factors, to produce an MR spectroscopy data record for said volume of interest; and

(e) from said control computer, making said MR spectroscopy data record available in electronic form as a data file.

2. A method as claimed in claim 1 comprising, in said control computer, determining said complex sensitivity factors by minimizing an L 2 norm between said reference signal and the respective FID signal of the respective other RF reception coil, weighted with the respective complex sensitivity factor thereof.

3. A method as claimed in claim 1 comprising determining said complex sensitivity factors in said control computer by minimizing the square root of a sum of squares of said difference.

4. A method as claimed in claim 1 comprising selecting a number of said other RF reception coils for which the respective differences are minimized.

5. A method as claimed in claim 1 comprising minimizing only said differences that have a value above a predetermined threshold value.

6. A method as claimed in claim 1 comprising using, as said at least two RF reception coils, at least two RF reception coils that are among an RF coil array of said MR scanner.

7. A method as claimed in claim 1 comprising repeating steps (a) thru (d) for respectively different volumes of interest.

8. A method as claimed in claim 7 comprising repeating steps (a) thru (d) for all voxels in a chemical shift imaging data record.

9. A method as claimed in claim 1 comprising operating said MR scanner from said control computer to acquire said FID signals using a sequence wherein said volume of interest is individually selected.

10. A method as claimed in claim 1 comprising, in said control computer, selecting the Rf reception coil as said reference coil that has an FID signal that has a highest signal-to-noise ratio among all of the respective FID signals of said at least two RF reception coils.

11. A method as claimed in claim 1 wherein said MR spectroscopy data are 1 H data, and, from said control computer, operating said MR scanner with water suppression during acquisition of said FID signals.

12. A method for determining a complex sensitivity factor of a radio-frequency (RF) reception coil of a magnetic resonance (MR) scanner that comprises a plurality of RF reception coils, comprising:

(a) operating an MR scanner, comprising at least two radio-frequency (RF) reception coils, from a control computer while an examination subject is situated in the MR scanner, to acquire respective free induction decays (FID) signals, representing MR spectroscopy data, from a volume of interest of the examination subject simultaneously with each of said RF reception coils;

(b) in said control computer, selecting one of said RF reception coils as a reference coil and designating the respective FID signal thereof as a reference signal;

(c) in said control computer, for each RF reception coil other than said reference coil, determining a complex sensitivity factor by minimizing a difference between a number of data points of the respective FID signal thereof, weighted with said complex sensitivity factor, and corresponding data points of the FID signal of the reference coil; and

(d) from said control computer, making the determined complex sensitivity factor available as an electronic signal for further processing.

13. A magnetic resonance (MR) apparatus comprising:

an MR scanner comprising a plurality of radio-frequency (RF) reception coils;

a control computer configured to operate said MR scanner while an examination subject is situated in the MR scanner, to acquire respective free induction decays (FID) signals, representing MR spectroscopy data, from a volume of interest of the examination subject simultaneously with each of said RF reception coils;

said control computer being configured to select one of said RF reception coils as a reference coil and to designate the respective FID signal thereof as a reference signal;

said control computer, for each RF reception coil other than said reference coil, being configured to determine a complex sensitivity factor by minimizing a difference between a number of data points of the respective FID signal thereof, weighted with said complex sensitivity factor, and corresponding data points of the FID signal of the reference coil;

said control computer being configured to combine MR spectroscopy data acquired from said volume of interest simultaneously with said RF reception coils, weighted with the respective complex sensitivity factors, to produce an MR spectroscopy data record for said volume of interest; and

said control computer being configured to make said MR spectroscopy data record available in electronic form as a data file.

14. A non-transitory, computer-readable data storage medium encoded with programming instructions, said storage medium being loaded into a control computer of a magnetic resonance (MR) apparatus that comprises an MR scanner having a plurality of radio-frequency (RF) reception coils, said programming instructions causing said control computer to:

operate said MR scanner while an examination subject is situated in the MR scanner, to acquire respective free induction decays (FID) signals, representing MR spectroscopy data, from a volume of interest of the examination subject simultaneously with each of said RF reception coils;

select one of said RF reception coils as a reference coil and designate the respective FID signal thereof as a reference signal;

for each RF reception coil other than said reference coil, determine a complex sensitivity factor by minimizing a difference between a number of data points of the respective FID signal thereof, weighted with said complex sensitivity factor, and corresponding data points of the FID signal of the reference coil;

combine MR spectroscopy data acquired from said volume of interest simultaneously with said RF reception coils, weighted with the respective complex sensitivity factors, to produce an MR spectroscopy data record for said volume of interest; and

make said MR spectroscopy data record available in electronic form as a data file.