Receiving Method, Receiving System for Magnetic Resonance Signals, and Magnetic Resonance Imaging System

• US 20130134980A1
• Filed: 11/29/2012
• Published: 05/30/2013
• Est. Priority Date: 11/30/2011
• Status: Active Grant

• Current Assignee: Siemens Healthineers AG (Siemens AG)
• Original Assignee: Siemens Healthcare GMBH (Siemens AG)
• Inventors: Vester, Markus, Wang, Jian Min, Wang, Lan, Li, Zhi Bin
• Granted Patent: US 9,465,092 B2
• Time in Patent Office: Days
• US Class Current: 324/322
• CPC Class Codes: G01R 33/3415 comprising arrays of sub-coils , i.e. phased-array coils with flexible receiver channels
• CPC Class Codes: G01R 33/3621 NMR receivers or demodulators, e.g. preamplifiers, means for frequency modulation of the MR signal using a digital down converter, means for analog to digital conversion [ADC] or for filtering or processing of the MR signal such as bandpass filtering, resampling, decimation or interpolation
• CPC Class Codes: G01R 33/54 Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console

Abstract

A method and system for receiving magnetic resonance signals, and a magnetic resonance imaging system are provided. The method includes dividing coil units in a receiving coil array into different coil unit groups. For each of the coil unit groups, correlations are established between carrier frequencies and the signals received by each coil unit in the coil unit group. Low noise amplification is performed, and filtering and frequency mixing is performed on the signals received by all the coil units in the coil unit group according to the correlations to obtain intermediate frequency signals borne on the respectively corresponding carrier frequencies of an identical channel. After performing amplification and filtering on the intermediate frequency signals, the intermediate frequency signals are output to an analog-to-digital conversion unit to perform digital sampling so as to obtain digital domain signals.

Claims

1. A system for receiving magnetic resonance signals, the system comprising:

a receiving coil array comprising at least one coil unit group;

a correlation recording unit configured to record correlations between carrier frequencies and signals received by each coil unit in a corresponding coil unit group of the at least one coil unit group;

a low noise amplification, filtering and frequency mixing unit configured to perform frequency mixing on anti-aliasing filtered signals according to the correlations recorded by the correlation recording unit after performing low noise amplification and anti-aliasing filtering on the signals received by the coil units in the at least one coil unit group to obtain intermediate frequency signals borne on the respectively corresponding carrier frequencies of an identical channel;

an amplification and filtering unit configured to perform amplification and filtering processing on the intermediate frequency signals; and

an analog-to-digital conversion unit configured to perform digital sampling on the signals processed by the amplification and filtering unit to obtain digital domain signals.

2. The system as claimed in claim 1, wherein each of the at least one coil unit group in the receiving coil array comprises coil units with a dynamic range of total receiving signals being not greater than a dynamic range of the analog-to-digital conversion unit.

3. The system as claimed in claim 1, further comprising a compression unit located between the amplification and filtering unit and the analog-to-digital conversion unit,

wherein the compression unit is configured to compress on signals from the amplification and filtering unit.

4. The system as claimed in claim 3, wherein each of the at least one coil unit group in the receiving coil array comprises coil units with a dynamic range of total receiving signals being not greater than a dynamic range co-determined by the analog-to-digital conversion unit and the compression unit.

5. The system as claimed in claim 1, wherein each of the at least one coil unit group in the receiving coil array comprises all the coil units that receive an identical orthogonal signal.

6. The system as claimed in claim 1, further comprising a digital processing unit configured to perform down-conversion processing on the digital domain signals according to the correlations recorded by the correlation recording unit.

7. The system as claimed in claim 1, wherein the at least one coil unit group comprises three coil units;

wherein the system further comprises a local oscillator signal frequency determination unit and a digital processing unit configured to select frequencies of required local oscillator signals during frequency mixing to make frequencies of the frequency mixed intermediate frequency signals meet the following relationship;

f_L=f_M+f_s/4, f_R=f_M−

f_s/4,

wherein f_s is a sampling rate of the analog-to-digital conversion unit, f_M is a frequency of the intermediate frequency signal of the coil unit located in the middle of the three coil units, f_L, is the frequency of the intermediate frequency signal of the coil unit located in the left of the three coil units, and f_R is a frequency of the intermediate frequency signal of the coil unit located in the right of the three coil units,

wherein the low noise amplification, filtering and frequency mixing unit is configured to perform frequency mixing on all the signals received by the at least one group of coil units using the local oscillator signals with the selected frequencies, and

wherein the digital processing unit is configured to extract the digital domain signals, taking a signal at a (4K+1)th sampling point as a merging signal with a maximum information amount of the signals received by the three coil units and outputting the signal at the (4K+1)th sampling point, and taking a signal at a (4K+3)th sampling point as a merging signal with a minimum information amount of the signals received by the three coil units and outputting the signal at the (4K+3)th sampling point, wherein K is an integer greater than or equal to 0.

8. The system as claimed in claim 3, wherein each of the at least one coil unit group in the receiving coil array comprises all the coil units that receive an identical orthogonal signal.

9. The system as claimed in claim 2, further comprising a digital processing unit configured to perform down-conversion processing on the digital domain signals according to the correlations recorded by the correlation recording unit.

10. The system as claimed in claim 3, further comprising a digital processing unit configured to perform down-conversion processing on the digital domain signals according to the correlations recorded by the correlation recording unit.

11. The system as claimed in claim 4, further comprising a digital processing unit configured to perform down-conversion processing on the digital domain signals according to the correlations recorded by the correlation recording unit.

12. A magnetic resonance imaging system comprising:

a magnetic resonance signal receiving system comprising;

a receiving coil array comprising at least one coil unit group;

a correlation recording unit configured to record correlations between carrier frequencies and signals received by each coil unit in a corresponding coil unit group of the at least one coil unit group;

a low noise amplification, filtering and frequency mixing unit configured to perform frequency mixing on anti-aliasing filtered signals according to the correlations recorded by the correlation recording unit after performing low noise amplification and anti-aliasing filtering on the signals received by the coil units in the at least one coil unit group to obtain intermediate frequency signals borne on the respectively corresponding carrier frequencies of an identical channel;

an amplification and filtering unit configured to perform amplification and filtering processing on the intermediate frequency signals; and

an analog-to-digital conversion unit configured to perform digital sampling on the signals processed by the amplification and filtering unit to obtain digital domain signals.

13. A method for receiving magnetic resonance signals, the method comprising:

after performing low noise amplification and anti-aliasing filtering on signals received by coil units in a coil unit group, performing frequency mixing on the anti-aliasing filtered signals according to correlations between carrier frequencies and the signals received by each coil unit in the coil unit group to obtain intermediate frequency signals borne on the respectively corresponding carrier frequencies of an identical channel; and

after amplifying and filtering the intermediate frequency signals, outputting the amplified and filtered intermediate frequency signals to an analog-to-digital conversion unit to perform digital sampling so as to obtain digital domain signals.

14. The method as claimed in claim 13, further comprising, before the outputting of the amplified and filtered intermediate frequency signals to the analog-to-digital conversion unit to perform digital sampling, compressing on the filtered signals using a compression unit, and outputting the compressed signals to the analog-to-digital conversion unit to perform digital sampling.

15. The method as claimed in claim 13, wherein the coil unit group comprises three coil units,

wherein the method further comprises, before performing frequency mixing on the anti-aliasing filtered signals, selecting frequencies of required local oscillator signals to make frequencies of the frequency mixed intermediate frequency signals meet the following relationship:

f_L=f_M+f_s/4, f_R=f_M−

f_s/4,

wherein f_s is a sampling rate of an analog-to-digital converter, f_M is a frequency of the intermediate frequency signal of the coil unit located in the middle of the three coil units, f_L, is a frequency of the intermediate frequency signal of the coil unit located in the left of the three coil units, and f_R is a frequency of the intermediate frequency signal of the coil unit located in the right of the three coil units,

wherein the frequency mixing comprises performing frequency mixing on the anti-aliasing filtered signals using the local oscillator signals with the selected frequencies, and

wherein the method further comprises, after the obtaining of the digital domain signals, extracting the digital domain signals, taking a signal at a (4K+1)th sampling point as a merging signal with a maximum information amount of the signals received by the three coil units and outputting the merging signal with the maximum information amount, and taking a signal at a (4K+3)th sampling point as a merging signal with a minimum information amount of the signals received by the three coil units and outputting the merging signal with the minimum information amount, wherein K is an integer greater than or equal to 0.