Method and system for composite gating using multiple inputs

• US 20050113672A1
• Filed: 11/26/2003
• Published: 05/26/2005
• Est. Priority Date: 11/26/2003
• Status: Active Grant

• Current Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Original Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Inventors: Bulkes, Cherik, Avinash, Gopal B., Salla, Prathyusha K.
• Granted Patent: US 7,756,565 B2
• Time in Patent Office: Days
• US Class Current: 600/413
• CPC Class Codes: A61B 5/0037 Performing a preliminary scan, e.g. a prescan for identifying a region of interest
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence
• CPC Class Codes: A61B 5/7289 Retrospective gating, i.e. associating measured signals or images with a physiological event after the actual measurement or image acquisition, e.g. by simultaneously recording an additional physiological signal during the measurement or image acquisition
• CPC Class Codes: A61B 5/7292 Prospective gating, i.e. predicting the occurrence of a physiological event for use as a synchronisation signal
• CPC Class Codes: A61B 6/503 for diagnosis of the heart
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: G01R 33/5673 Gating or triggering based on a physiological signal other than an MR signal, e.g. ECG gating or motion monitoring using optical systems for monitoring the motion of a fiducial marker

Abstract

One or more techniques are provided for determining the overall motion of an organ of interest relative to a viewer or imager. Motion data is acquired for the organ of interest and/or for one or more proximate organs using sensor-based and/or image data-based techniques. The sensor-based techniques may include electrical and non-electrical techniques. The image data-based techniques may include both pre-acquisition and acquisition image data. The motion data for the organ of interest and proximate organs may be used to determine one or more quiescent periods corresponding to intervals of minimal motion for the organ of interest and the proximate organs. The one or more quiescent periods may be used to determine one or more gating points that may be used prospectively, i.e., during image acquisition, and retrospectively, i.e., after image acquisition. In addition, the one or more quiescent periods may be used to determine one or more motion compensation factors that may be used during processing and reconstruction of the acquired image data. The gating points and motion compensation factors may be used, separately or together, to reduce motion-related artifacts in the reconstructed images.

Claims

1. A method for imaging an organ, comprising the steps of:

acquiring a set of motion data for two or more organs from at least one of one or more types of electrical sensors and one or more types of non-electrical sensors;

processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for an organ of interest;

acquiring a set of image data representative of the organ of interest using the two or more prospective gating points; and

processing a portion of the set of image data based upon the two or more retrospective gating points.

2. A computer program, provided on one or more computer readable media, for imaging an organ, comprising:

a routine for acquiring a set of motion data for two or more organs from at least one of one or more types of electrical sensors and one or more types of non-electrical sensors;

a routine for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for an organ of interest;

a routine for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points; and

a routine for processing a portion of the set of image data based upon the two or more retrospective gating points.

3. An imaging system, comprising:

an imager configured to generate a plurality of signals representative of a region of interest;

data acquisition circuitry configured to acquire the plurality of signals;

data processing circuitry configured to receive the plurality of signals, to process a set of motion data describing the motion of two or more organs to derive two or more retrospective gating points for at least one of the organs, and to process a portion of the plurality of signals based upon the two or more retrospective gating signals;

system control circuitry configured to operate at least one of the imager and the data acquisition circuitry based upon two or more prospective gating points derived from the set of motion data;

an operator workstation configured to communicate with the system control circuitry and to receive at least the processed portion of the plurality of signals from the data processing circuitry; and

a sensor-based motion measurement system configured to measure electrical or non-electrical activity indicative of the motion of at least one of the two or more organs within the region of interest to contribute to the set of motion data.

4. An imaging system, comprising:

means for acquiring a set of motion data for two or more organs from at least one of one or more types of electrical sensors and one or more types of non-electrical sensors;

means for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for an organ of interest;

means for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points; and

means for processing a portion of the set of image data based upon the two or more retrospective gating points.

5. A method for imaging an organ, comprising the steps of:

acquiring a set of motion data for two or more organs from at least one of one or more types of electrical sensors and one or more types of non-electrical sensors;

processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for an organ of interest;

acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

reconstructing the set of image data to generate a set of reconstructed data; and

processing a portion of the set of reconstructed data based upon the two or more retrospective gating points.

6. A computer program, provided on one or more computer readable media, for imaging an organ, comprising:

a routine for acquiring a set of motion data for two or more organs from at least one of one or more types of electrical sensors and one or more types of non-electrical sensors;

a routine for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for an organ of interest;

a routine for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

a routine for reconstructing the set of image data to generate a set of reconstructed data; and

a routine for processing a portion of the set of reconstructed data based upon the two or more retrospective gating points.

7. An imaging system, comprising:

an imager configured to generate a plurality of signals representative of a region of interest;

data acquisition circuitry configured to acquire the plurality of signals;

data processing circuitry configured to receive the plurality of signals, to process a set of motion data describing the motion of two or more organs to derive two or more retrospective gating points for at least one of the organs, to reconstruct the plurality of signals to generate a set of reconstructed data, and to process a portion of the reconstructed data based upon the two or more retrospective gating signals;

system control circuitry configured to operate at least one of the imager and the data acquisition circuitry based upon two or more prospective gating points derived from the set of motion data;

an operator workstation configured to communicate with the system control circuitry and to receive at least the processed portion of the plurality of signals from the data processing circuitry; and

a sensor-based motion measurement system configured to measure electrical or non-electrical activity indicative of the motion of at least one of the two or more organs within the region of interest to contribute to the set of motion data.

8. An imaging system, comprising:

means for acquiring a set of motion data for two or more organs from at least one of one or more types of electrical sensors and one or more types of non-electrical sensors;

means for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for an organ of interest;

means for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

means for reconstructing the set of image data to generate a set of reconstructed data; and

means for processing a portion of the set of reconstructed data based upon the two or more retrospective gating points.

9. A method for imaging an organ, comprising the steps of:

acquiring a set of motion data for an organ of interest from at least one or more non-electrical sensors;

processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the organ of interest;

acquiring a set of image data representative of the organ of interest using the two or more prospective gating points; and

processing a portion of the set of image data based upon the two or more retrospective gating points.

10. A computer program, provided on one or more computer readable media, for imaging an organ, comprising:

a routine for acquiring a set of motion data for an organ of interest from at least one or more non-electrical sensors;

a routine for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the organ of interest;

a routine for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points; and

a routine for processing a portion of the set of image data based upon the two or more retrospective gating points.

11. An imaging system, comprising:

an imager configured to generate a plurality of signals representative of a region of interest;

data acquisition circuitry configured to acquire the plurality of signals;

data processing circuitry configured to receive the plurality of signals, to process a set of motion data describing the motion of an organ of interest to derive two or more retrospective gating point for the organ, and to process a portion of the plurality of signals based upon the two or more retrospective gating signals;

system control circuitry configured to operate at least one of the imager and the data acquisition circuitry based upon two or more prospective gating points derived from the set of motion data;

an operator workstation configured to communicate with the system control circuitry and to receive at least the processed portion of the plurality of signals from the data processing circuitry; and

a sensor-based motion measurement system configured to measure non-electrical activity indicative of the motion of the organ of interest to contribute to the set of motion data.

12. An imaging system, comprising:

means for acquiring a set of motion data for an organ from at least one or more non-electrical sensors;

means for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for an organ of interest;

means for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points; and

means for processing a portion of the set of image data based upon the two or more retrospective gating points.

13. A method for imaging an organ, comprising the steps of:

acquiring a set of motion data for an organ of interest from at least one or more non-electrical sensors;

processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the organ of interest;

acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

reconstructing the set of image data to generate a set of reconstructed data; and

processing a portion of the set of reconstructed data based upon the two or more retrospective gating points.

14. A computer program, provided on one or more computer readable media, for imaging an organ, comprising:

a routine for acquiring a set of motion data for an organ of interest from at least one or more non-electrical sensors;

a routine for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the organ of interest;

a routine for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

a routine for reconstructing the set of image data to generate a set of reconstructed data; and

a routine for processing a portion of the set of reconstructed data based upon the two or more retrospective gating points.

15. An imaging system, comprising:

an imager configured to generate a plurality of signals representative of a region of interest;

data acquisition circuitry configured to acquire the plurality of signals;

data processing circuitry configured to receive the plurality of signals, to process a set of motion data describing the motion of an organ of interest to derive two or more retrospective gating points, to reconstruct the plurality of signals to generate a set of reconstructed data, and to process a portion of the reconstructed data based upon the two or more retrospective gating signals;

system control circuitry configured to operate at least one of the imager and the data acquisition circuitry based upon two or more prospective gating points derived from the set of motion data;

an operator workstation configured to communicate with the system control circuitry and to receive at least the processed portion of the plurality of signals from the data processing circuitry; and

a sensor-based motion measurement system configured to measure non-electrical activity indicative of the motion of the organ of interest to contribute to the set of motion data.

16. An imaging system, comprising:

means for acquiring a set of motion data for an organ of interest from at least one or more non-electrical sensors;

means for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the organ of interest;

means for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

means for reconstructing the set of image data to generate a set of reconstructed data; and

means for processing a portion of the set of reconstructed data based upon the two or more retrospective gating points.

17. A method for imaging an organ, comprising the steps of:

acquiring a set of motion data for a respiratory organ of interest from at least one or more electrical sensors;

processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the respiratory organ of interest;

acquiring a set of image data representative of the respiratory organ of interest using the two or more prospective gating points; and

processing a portion of the set of image data based upon the two or more retrospective gating points.

18. A computer program, provided on one or more computer readable media, for imaging an organ, comprising:

a routine for acquiring a set of motion data for a respiratory organ of interest from at least one or more electrical sensors;

a routine for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the respiratory organ of interest;

a routine for acquiring a set of image data representative of the respiratory organ of interest using the two or more prospective gating points; and

a routine for processing a portion of the set of image data based upon the two or more retrospective gating points.

19. An imaging system, comprising:

an imager configured to generate a plurality of signals representative of a region of interest;

data acquisition circuitry configured to acquire the plurality of signals;

data processing circuitry configured to receive the plurality of signals, to process a set of motion data describing the motion of a respiratory organ of interest to derive two or more retrospective gating point for the respiratory organ, and to process a portion of the plurality of signals based upon the two or more retrospective gating signals;

system control circuitry configured to operate at least one of the imager and the data acquisition circuitry based upon two or more prospective gating points derived from the set of motion data;

an operator workstation configured to communicate with the system control circuitry and to receive at least the processed portion of the plurality of signals from the data processing circuitry; and

a sensor-based motion measurement system configured to measure electrical activity indicative of the motion of the respiratory organ of interest to contribute to the set of motion data.

20. An imaging system, comprising:

means for acquiring a set of motion data for a respiratory organ of interest from at least one or more electrical sensors;

means for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the respiratory organ of interest;

means for acquiring a set of image data representative of the respiratory organ of interest using the two or more prospective gating points; and

means for processing a portion of the set of image data based upon the two or more retrospective gating points.

21. A method for imaging an organ, comprising the steps of:

acquiring a set of motion data for a respiratory organ of interest from at least one or more electrical sensors;

processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the respiratory organ of interest;

acquiring a set of image data representative of the respiratory organ of interest using the two or more prospective gating points;

reconstructing the set of image data to generate a set of reconstructed data; and

processing a portion of the set of reconstructed data based upon the two or more retrospective gating points.

22. A computer program, provided on one or more computer readable media, for imaging an organ, comprising:

a routine for acquiring a set of motion data for a respiratory organ of interest from at least one or more electrical sensors;

a routine for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the respiratory organ of interest;

a routine for acquiring a set of image data representative of the respiratory organ of interest using the two or more prospective gating points;

a routine for reconstructing the set of image data to generate a set of reconstructed data; and

a routine for processing a portion of the set of reconstructed data based upon the two or more retrospective gating points.

23. An imaging system, comprising:

an imager configured to generate a plurality of signals representative of a region of interest;

data acquisition circuitry configured to acquire the plurality of signals;

data processing circuitry configured to receive the plurality of signals, to process a set of motion data describing the motion of a respiratory organ of interest to derive two or more retrospective gating points, to reconstruct the plurality of signals to generate a set of reconstructed data, and to process a portion of the reconstructed data based upon the two or more retrospective gating signals;

system control circuitry configured to operate at least one of the imager and the data acquisition circuitry based upon two or more prospective gating points derived from the set of motion data;

an operator workstation configured to communicate with the system control circuitry and to receive at least the processed portion of the plurality of signals from the data processing circuitry; and

a sensor-based motion measurement system configured to measure electrical activity indicative of the motion of the respiratory organ of interest to contribute to the set of motion data.

24. An imaging system, comprising:

means for acquiring a set of motion data for a respiratory organ of interest from at least one or more electrical sensors;

means for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the respiratory organ of interest;

means for acquiring a set of image data representative of the respiratory organ of interest using the two or more prospective gating points;

means for reconstructing the set of image data to generate a set of reconstructed data; and

means for processing a portion of the set of reconstructed data based upon the two or more retrospective gating points.

25. A method for imaging an organ, comprising the steps of:

acquiring a set of motion data for an organ of interest from one or more non-electrical sensors and one or more electrical sensors;

processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the organ of interest;

acquiring a set of image data representative of the organ of interest using the two or more prospective gating points; and

processing a portion of the set of image data based upon the two or more retrospective gating points.

26. A computer program, provided on one or more computer readable media, for imaging an organ, comprising:

a routine for acquiring a set of motion data for an organ of interest from one or more non-electrical sensors and one or more electrical sensors;

a routine for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the organ of interest;

a routine for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points; and

a routine for processing a portion of the set of image data based upon the two or more retrospective gating points.

27. An imaging system, comprising:

an imager configured to generate a plurality of signals representative of a region of interest;

data acquisition circuitry configured to acquire the plurality of signals;

data processing circuitry configured to receive the plurality of signals, to process a set of motion data describing the motion of an organ of interest to derive two or more retrospective gating point for the organ, and to process a portion of the plurality of signals based upon the two or more retrospective gating signals;

system control circuitry configured to operate at least one of the imager and the data acquisition circuitry based upon two or more prospective gating points derived from the set of motion data;

an operator workstation configured to communicate with the system control circuitry and to receive at least the processed portion of the plurality of signals from the data processing circuitry;

a sensor-based motion measurement system configured to measure non-electrical activity indicative of the motion of the organ of interest to contribute to the set of motion data; and

a sensor-based motion measurement system configured to measure electrical activity indicative of the motion of the organ of interest to contribute to the set of motion data.

28. An imaging system, comprising:

means for acquiring a set of motion data for an organ from one or more non-electrical sensors and one or more electrical sensors;

means for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for an organ of interest;

means for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points; and

means for processing a portion of the set of image data based upon the two or more retrospective gating points.

29. A method for imaging an organ, comprising the steps of:

acquiring a set of motion data for an organ of interest from one or more non-electrical sensors and one or more electrical sensors;

processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the organ of interest;

acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

reconstructing the set of image data to generate a set of reconstructed data; and

processing a portion of the set of reconstructed data based upon the two or more retrospective gating points.

30. A computer program, provided on one or more computer readable media, for imaging an organ, comprising:

a routine for acquiring a set of motion data for an organ of interest from one or more non-electrical sensors and one or more electrical sensors;

a routine for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the organ of interest;

a routine for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

a routine for reconstructing the set of image data to generate a set of reconstructed data; and

a routine for processing a portion of the set of reconstructed data based upon the two or more retrospective gating points.

31. An imaging system, comprising:

an imager configured to generate a plurality of signals representative of a region of interest;

data acquisition circuitry configured to acquire the plurality of signals;

data processing circuitry configured to receive the plurality of signals, to process a set of motion data describing the motion of an organ of interest to derive two or more retrospective gating points, to reconstruct the plurality of signals to generate a set of reconstructed data, and to process a portion of the reconstructed data based upon the two or more retrospective gating signals;

system control circuitry configured to operate at least one of the imager and the data acquisition circuitry based upon two or more prospective gating points derived from the set of motion data;

an operator workstation configured to communicate with the system control circuitry and to receive at least the processed portion of the plurality of signals from the data processing circuitry;

a sensor-based motion measurement system configured to measure non-electrical activity indicative of the motion of the organ of interest to contribute to the set of motion data;

a sensor-based motion measurement system configured to measure electrical activity indicative of the motion of the organ of interest to contribute to the set of motion data.

32. An imaging system, comprising:

means for acquiring a set of motion data for an organ of interest from one or more non-electrical sensors one or more electrical sensors;

means for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for the organ of interest;

means for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

means for reconstructing the set of image data to generate a set of reconstructed data; and

means for processing a portion of the set of reconstructed data based upon the two or more retrospective gating points.

33. A method for imaging an organ, comprising the steps of:

acquiring a set of motion data for one or more organs from at least one of one or more types of electrical sensors and one or more types of non-electrical sensors;

processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for an organ of interest;

acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

processing a portion of the set of image data based upon the two or more retrospective gating points; and

compensating for motion in the portion of the set of image data based upon a set of motion compensation factors derived from one or more pre-acquisition images.

34. A computer program, provided on one or more computer readable media, for imaging an organ, comprising:

a routine for acquiring a set of motion data for one or more organs from at least one of one or more types of electrical sensors and one or more types of non-electrical sensors;

a routine for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for an organ of interest;

a routine for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

a routine for processing a portion of the set of image data based upon the two or more retrospective gating points; and

a routine for compensating for motion in the portion of the set of image data based upon a set of motion compensation factors derived from one or more pre-acquisition images.

35. An imaging system, comprising:

an imager configured to generate a plurality of signals representative of a region of interest;

data acquisition circuitry configured to acquire the plurality of signals;

data processing circuitry configured to receive the plurality of signals, to process a set of motion data describing the motion of one or more organs to derive two or more retrospective gating points for at least one of the organs, to process a portion of the plurality of signals based upon the two or more retrospective gating signals, and to compensate for motion in the portion of the set of image data based upon a set of motion compensation factors derived from one or more pre-acquisition images;

system control circuitry configured to operate at least one of the imager and the data acquisition circuitry based upon two or more prospective gating points derived from the set of motion data;

an operator workstation configured to communicate with the system control circuitry and to receive at least the processed portion of the plurality of signals from the data processing circuitry; and

a sensor-based motion measurement system configured to measure electrical or non-electrical activity indicative of the motion of the one or more organs within the region of interest to contribute to the set of motion data.

36. An imaging system, comprising:

means for acquiring a set of motion data for one or more organs from at least one of one or more types of electrical sensors and one or more types of non-electrical sensors;

means for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for an organ of interest;

means for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

means for processing a portion of the set of image data based upon the two or more retrospective gating points; and

means for compensating for motion in the portion of the set of image data based upon a set of motion compensation factors derived from one or more pre-acquisition images.

37. A method for imaging an organ, comprising the steps of:

acquiring a set of motion data for one or more organs from at least one of one or more types of electrical sensors and one or more types of non-electrical sensors;

processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for an organ of interest;

acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

reconstructing the set of image data to generate a set of reconstructed data; and

processing a portion of the set of reconstructed data based upon the two or more retrospective gating points; and

compensating for motion in the portion of the set of reconstructed data based upon a set of motion compensation factors derived from one or more pre-acquisition images.

38. A computer program, provided on one or more computer readable media, for imaging an organ, comprising:

a routine for acquiring a set of motion data for one or more organs from at least one of one or more types of electrical sensors and one or more types of non-electrical sensors;

a routine for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for an organ of interest;

a routine for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

a routine for reconstructing the set of image data to generate a set of reconstructed data;

a routine for processing a portion of the set of reconstructed data based upon the two or more retrospective gating points; and

a routine for compensating for motion in the portion of the set of reconstructed data based upon a set of motion compensation factors derived from one or more pre-acquisition images.

39. An imaging system, comprising:

an imager configured to generate a plurality of signals representative of a region of interest;

data acquisition circuitry configured to acquire the plurality of signals;

data processing circuitry configured to receive the plurality of signals, to process a set of motion data describing the motion of one or more organs to derive two or more retrospective gating points for at least one of the organs, to reconstruct the plurality of signals to generate a set of reconstructed data, to process a portion of the reconstructed data based upon the two or more retrospective gating signals, and to compensate for motion in the portion of the set of reconstructed data based upon a set of motion compensation factors derived from one or more pre-acquisition images;

system control circuitry configured to operate at least one of the imager and the data acquisition circuitry based upon two or more prospective gating points derived from the set of motion data;

an operator workstation configured to communicate with the system control circuitry and to receive at least the processed portion of the plurality of signals from the data processing circuitry; and

a sensor-based motion measurement system configured to measure electrical or non-electrical activity indicative of the motion of the one or more organs within the region of interest to contribute to the set of motion data.

40. An imaging system, comprising:

means for acquiring a set of motion data for one or more organs from at least one of one or more types of electrical sensors and one or more types of non-electrical sensors;

means for processing the set of motion data to extract two or more prospective gating points and two or more retrospective gating points for an organ of interest;

means for acquiring a set of image data representative of the organ of interest using the two or more prospective gating points;

means for reconstructing the set of image data to generate a set of reconstructed data;

means for processing a portion of the set of reconstructed data based upon the two or more retrospective gating points; and

means for compensating for motion in the portion of the set of reconstructed data based upon a set of motion compensation factors derived from one or more pre-acquisition images.