Clock generation in MRI receivers

• US 8,575,935 B2
• Filed: 12/04/2008
• Issued: 11/05/2013
• Est. Priority Date: 12/11/2007
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Roeven, Henricus Gerardus
• Primary Examiner(s): Vargas, Dixomara
• Application Number:
  US12/746,785
• Publication Number:
  US 20100260293A1
• Time in Patent Office: 1,797 Days
• Field of Search: 324300-322
• US Class Current: 324/322
• 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 33/3692 involving signal transmission without using electrically conductive connections, e.g. wireless communication or optical communication of the MR signal or an auxiliary signal other than the MR signal
• CPC Class Codes: H03M 1/1245 Details of sampling arrangements or methods

Abstract

The invention relates to a nuclear magnetic resonance imaging radio frequency receiver, the receiver being adapted to receive analogue signals from at least one radio frequency receiver coil unit (122; 204; 306), the radio frequency receiver comprising an analogue-digital converter (408) to convert the analogue magnetic resonance signal into a first digital signal, a resampling and demodulation unit (414) to convert the first digital signal into a second digital signal, a communication interface (400: 600; 602) adapted for transmitting the second digital signal via a communication link (202), and a first clock generator (406) for generating a sampling clock, the sampling clock being the direct clock source for the analogue-digital converter (408), the first clock generator (406) being adapted to generate the sampling clock using a digital timing reference, the digital timing reference being received digitally via the communication link (202) by the communication interface (400: 600; 602), wherein the receiver further comprises a second clock generator (410) for generating a system clock, the system clock being the direct clock source for the resampling and demodulation unit (414), the second clock generator (410) being adapted to generate the system clock using the sampling clock.

Claims

1. A radio frequency receiver for receiving analogue signals from at least one radio frequency receiver coil unit of a nuclear magnetic resonance imaging (MRI) system, the radio frequency receiver being integrated with the radio frequency receiver coil unit within an examination room, the radio frequency receiver comprising:

an analogue-digital converter configured to convert the received analogue signals into a first digital signal;

a resampling and digital demodulation unit configured to convert the first digital signal into a second digital signal;

a communication interface configured to send the second digital signal to a control and data acquisition system via a communication link;

a first clock generator configured to generate a sampling clock for clocking the analogue-digital converter using a digital timing reference from a master clock in the control and data acquisition system, the digital timing reference being received in a datastream by the communication interface via the communication link; and

a second clock generator configured to generate a system clock for clocking the resampling and demodulation unit, the system clock being derived from the sampling clock.

2. The receiver as claimed in claim 1, further comprising:

a third clock generator configured to generate a data clock for clocking the communication interface, the third clock being derived from one of the sampling clock or the system clock.

3. The receiver as claimed in claim 2, wherein the first clock generator and the third clock generator form a feedback loop, and wherein the first clock generator is controlled by the feedback loop.

4. The receiver as claimed in claim 3, wherein the second clock generator is comprised in the feedback loop.

5. The receiver as claimed in claim 3, wherein the feedback loop is a phase locked loop.

6. The receiver as claimed in claim 2, wherein the data clock is a multi phase clock, wherein the communication interface is further configured to perform a recovery of the data clock from the multi-phase clock, and wherein the recovered data clock is usable to recover data in the datastream.

7. The receiver as claimed in claim 2, further comprising:

at least one additional communication interface, providing multiple communication interfaces, the multiple communication interfaces being configured for daisy-chaining of further receivers.

8. The receiver as claimed in claim 7, wherein each communication interface individually and dynamically recovers the data clock from a centrally generated multi phase clock.

9. The receiver as claimed in claim 1, wherein the digital timing reference which is received digitally via the communication link is received as a serial data bitstream.

10. The receiver as claimed in claim 1, further comprising:

a plurality of receiver channels, one receiver channel comprising the analogue-digital converter and the resampling and digital demodulation unit,

wherein the sampling clock, the system clock and the communication interface are common to the plurality of receiver channels.

11. The receiver as claimed in claim 1, wherein the system clock and the sampling clock run at the same frequency.

12. The receiver as claimed in claim 1, wherein the control and data acquisition system is located within a technical room remote from the examination room.

13. A method of receiving a radio frequency signal from a magnetic resonance imaging receiver coil unit at a nuclear magnetic resonance imaging radio frequency receiver integrated with the receiver coil unit, the method comprising:

receiving an analogue nuclear magnetic resonance signal from the radio frequency receiver coil unit;

converting the analogue magnetic resonance signal into a first digital signal using an analogue-digital converter;

receiving a digital timing reference from a master clock in a control and data acquisition system via a communication link using a communication interface;

generating a sampling a clock for clocking the analogue-digital converter using the digital timing reference and data acquisition system;

resampling the first digital signal into a second digital signal using a resampling and digital demodulation unit, and communicating the second digital signal to the control and data acquisition system via the communication link; and

deriving a system clock from the sampling clock for clocking the resampling and demodulation unit.

14. The method as claimed in claim 13, further comprising:

deriving a data clock from one of the sampling clock and the system clock for clocking the communication interface.

15. The method as claimed in claim 14, wherein the digital timing reference is received as a serial data bitstream, and wherein the data clock is a multi-phase clock, the method further comprising:

recovering by the communication interface the data clock from the multi-phase clock and recovering the data comprised in the serial data bitstream using the recovered data clock.

16. A non-transitory computer program product comprising computer executable instructions to perform any of the method steps as claimed in claim 13.