Motion Compensation in Functional Imaging

• US 20080226149A1
• Filed: 07/27/2006
• Published: 09/18/2008
• Est. Priority Date: 08/04/2005
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Carlsen, Ingwer-Curt, Shao, Lingxiong, Meyer, Carsten, Wischmann, Hans-Aloys, Da Silva, Angela
• Granted Patent: US 8,411,915 B2
• Time in Patent Office: Days
• US Class Current: 382/131
• CPC Class Codes: A61B 5/113 occurring during breathing
• 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 6/037 Emission tomography
• CPC Class Codes: A61B 6/503 for diagnosis of the heart
• CPC Class Codes: A61B 6/5235 combining images from the same or different ionising radiation imaging techniques, e.g. PET and CT
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: A61B 8/0883 for diagnosis of the heart
• CPC Class Codes: G06T 11/005 Specific pre-processing for tomographic reconstruction, e.g. calibration, source positioning, rebinning, scatter correction, retrospective gating
• CPC Class Codes: G06T 2207/30004 Biomedical image processing
• CPC Class Codes: G06T 2211/412 Dynamic
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51

Abstract

Medical images are collected in a plurality of cardiac and respiratory phases. The images are transformed into a series of respiratory compensated images with the plurality of cardiac phases, but all at a common respiration phase. The series of respiratory compensated images are transformed into one image at a selected cardiac phase and the common respiration phase. In some embodiments, a database of gated transform matrices is generated. The database may be based on specific patient information or on information generated from a pool of patients. The database may account for respiratory motion, cardiac contractile motion, other physiological motion, or combinations thereof. For a current image to be motion corrected, the transformation matrices collected in the database are used to estimate a current set of transformation matrices accounting for the motion in the current image, and a motion-compensated image is generated based on the current set of transform matrices.

Claims

1. A method of respiratory and cardiac movement compensated diagnostic imaging comprising:

generating a plurality of heart images in each of a plurality of respiratory and cardiac phases with a first imaging modality;

transforming images of the plurality of images which have a common cardiac phase and different respiratory phases into a series of respiratory compensated images at the plurality of cardiac phases and at a selected common respiratory phase;

transforming the series of respiratory compensated images in accordance with a heart shape and motion model to generate a series of cardiac and respiratory compensated images in a selected common cardiac phase and the selected common respiratory phase; and

,

combining the images in the selected common cardiac and respiratory phases.

2. The method according to claim 1 further including:

generating images of a heart of a subject in each of a plurality of cardiac phases with a second imaging modality;

fitting a generic heart shape and motion model to the generated heart images to generate a subject specific heart shape and motion model.

3. The method according to claim 2, wherein the second imaging modality is nuclear.

4. The method according to claim 3, wherein the first imaging modality is cardiac gated CT.

5. The method according to claim 4, wherein the first plurality of images is generated from CT data collected during a single breath hold.

6. The method according to claim 2, wherein the plurality of first imaging modality images are in a common respiratory phase.

7. The method according to claim 1, wherein the plurality of first imaging modality images includes images in each of N cardiac phases and M respiratory phases, where N and M are plural integers, such that the plurality of first imaging modality images includes N×

M images.

8. The method according to claim 7, wherein the N respiratory phases include a maximum inhale phase and a maximum exhale phase.

9. The method according to claim 1, wherein generating the plurality of first imaging modality images includes:

acquiring data with cardiac and respiratory gating; and

,

reconstructing data with common respiratory and cardiac phases into the plurality of first imaging modality images.

10. The method according to claim 1 wherein the plurality of generated heart images are current estimate heart images and iteratively repeating the following steps until a stop condition is met:

performing the first and second transforming steps with the estimate heart images to generate a series of cardiac and respiratory compensated estimate images;

projecting the series of cardiac and respiratory compensated estimate images to generate a series of projection estimates;

comparing the projection estimates with measured projections to generate a series of ratios;

reconstructing the ratios to generate a series of update factors;

applying inverses of the first and second transforming steps to generate an overall update factor.

11. A diagnostic imaging apparatus including a processor programmed to perform the method of claim 1.

12. A method of compensating for respiratory and cardiac movement in diagnostic image reconstruction comprising:

monitoring respiratory activity of a subject during a nuclear imaging scan and creating a respiratory movement vector;

monitoring cardiac activity of the subject during the scan;

binning raw image data acquired during the scan in accordance with its occurrence in both respiratory and cardiac phases;

reconstructing the binned raw data into a plurality of images;

transforming the images in accordance with the respiratory movement vector;

adjusting the resultant transformed images in accordance with a heart shape and motion model; and

,

combining the adjusted images.

13. A diagnostic imaging apparatus comprising:

a first modality scanner that generates a plurality of heart images in each of a plurality of respiratory and cardiac phases;

a respiratory adjustment processor that transforms images of the plurality of images which have a common cardiac phase and different respiratory phases into a series of respiratory compensated images at the plurality of cardiac phases at a selected common respiratory phase;

a cardiac transforming routine that transforms the series of respiratory compensated images in accordance with a heart shape and motion model to generate a series of cardiac and respiratory compensated images in a selected common cardiac phase and the selected common respiratory phase; and

,

a cardiac summing routine that combines the images in the selected common cardiac and respiratory phases.

14. The diagnostic imaging apparatus according to claim 13, further including:

a cardiac model generating scanner that generates images of a heart of a subject in each of a plurality of cardiac phases with a first imaging modality;

a model creation processor that fits a heart shape and motion model to the generated heart images to generate a subject specific heart movement model.

15. An image reconstruction processor for use in conjunction with cardiac nuclear imaging procedures comprising:

a respiratory adjustment processor that receives a plurality of images of differing respiratory phases and differing cardiac phases and adjusts the images of differing respiratory phases and cardiac phases into a series of images with a common respiratory phase and the differing cardiac phases;

a cardiac adjustment processor that receives the series images from the respiratory adjustment processor and adjusts the series images into a common cardiac phase and the common respiratory phase.

16. The image reconstruction processor according to claim 15, wherein the respiratory adjustment processor (32) includes:

a transformation routine, such as a translation that transforms images of different respiratory phases and the same cardiac phase to spatially overlay each other.

17. The image reconstruction processor according to claim 15, wherein the cardiac adjustment processor includes:

a transform calculating routine that creates a transform for warping, translating rotating, and zooming the series images at the differing cardiac phases into the common cardiac phase.

18. The image reconstruction processor according to claim 17, wherein the cardiac adjustment processor further includes:

a transform application routine that applies the transform to each image of the series images to generate a series of images with the common respiratory phase and the common cardiac phase.

19. A diagnostic imaging apparatus comprising:

a processor or algorithm which determines a transform from a heart shape and motion model;

a processor or transform which applies the determined transform to nuclear image data to transform the image data to a common cardiac phase;

a combining processor or algorithm which combines the transformed image data into a cardiac image in a selected cardiac phase.

20. The diagnostic imaging apparatus according to claim 19 wherein the nuclear image data to be transformed has been corrected for respiratory motion.

21. The diagnostic imaging apparatus according to claim 20 wherein the nuclear image data is respiratory motion corrected to a selected respiratory phase selected from only those respiratory phases which are sufficiently stable to avoid blurring artifacts.

22. A method of compensating for motion in medical imaging comprising:

generating a database of gated transform matrices based on image data from a patient pool, wherein the gated transform matrices compensate for respiratory motion;

acquiring gated image data for a current image to be motion corrected;

reconstructing the image data to form gated images;

using the transformation matrices collected in the database to estimate a current set of transformation matrices accounting for respiratory motion; and

generating a current motion-compensated image based on the current set of transform matrices.

23. The method of claim 22 further including generating a database of transform matrices compensating for other physiological motion and wherein the current set of transform matrices are based on the respiratory motion transform matrices and the physiological motion transform matrices from the respective databases.

24. The method of claim 23 wherein the physiological motion compensation transform matrices account for cardiac, peristaltic or other physiological motion.

25. A user interface for a medical imaging system comprising:

a display for displaying images; and

a motion compensation selector, wherein the motion compensation selection mechanism allows the user to select a motion compensation method.

26. The user interface of claim 25, wherein the selectable motion compensation method includes at least one of a specific patient model based motion compensation method and general database based motion compensation method.

27. The user interface of claim 25, wherein the selectable motion compensation method includes both a specific patient model based motion compensation method and general database based motion compensation method.

28. The user interface of claim 26 further comprising a motion compensation method selector, wherein the motion type includes respiratory and other physiological motion.

29. The user interface of claim 27 further comprising a motion compensation method selector, wherein the motion type includes respiratory and other physiological motion.