Model based estimation of a complete or partial positron emission tomography attenuation map using maximum likelihood expectation maximization

• US 20110015904A1
• Filed: 07/16/2009
• Published: 01/20/2011
• Est. Priority Date: 07/16/2009
• Status: Active Grant

• Current Assignee: Siemens Healthineers AG (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Michel, Christian J., Fenchel, Matthias, Ladebeck, Ralf, Watson, Charles C.
• Granted Patent: US 8,299,438 B2
• Time in Patent Office: Days
• US Class Current: 703/2
• CPC Class Codes: A61B 6/037 Emission tomography
• 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 6/5247 combining images from an ionising-radiation diagnostic technique and a non-ionising radiation diagnostic technique, e.g. X-ray and ultrasound
• CPC Class Codes: G01R 33/481 MR combined with positron emission tomography [PET] or single photon emission computed tomography [SPECT]
• CPC Class Codes: G01R 33/5608 Data processing and visualization specially adapted for MR, e.g. for feature analysis and pattern recognition on the basis of measured MR data, segmentation of measured MR data, edge contour detection on the basis of measured MR data, for enhancing measured MR data in terms of signal-to-noise ratio by means of noise filtering or apodization, for enhancing measured MR data in terms of resolution by means for deblurring, windowing, zero filling, or generation of gray-scaled images, colour-coded images or images displaying vectors instead of pixels image data processing or generation, in general G06T
• CPC Class Codes: G06T 11/005 Specific pre-processing for tomographic reconstruction, e.g. calibration, source positioning, rebinning, scatter correction, retrospective gating

Abstract

Example embodiments are directed to a method of correcting attenuation in a magnetic resonance (MR) scanner and a positron emission tomography (PET) unit. The method includes acquiring PET sinogram data of an object within a field of view of the PET unit. The method further includes producing an attenuation map based on a maximum likelihood expectation maximization (MLEM) of a parameterized model instance and the PET sinogram data.

Claims

1. A method of correcting attenuation in a magnetic resonance (MR) scanner and a positron emission tomography (PET) unit, the method comprising:

acquiring PET sinogram data of an object within a field of view of the PET unit; and

producing an attenuation map based on a maximum likelihood expectation maximization (MLEM) of a parameterized model instance and the PET sinogram data.

2. The method of claim 1, further comprising:

acquiring MR data of an object within a field of view of the MR scanner; and

producing a first attenuation map based on the acquired MR data.

3. The method of claim 2, wherein the producing the attenuation map includes producing the first attenuation map and a second attenuation map.

4. The method of claim 3, wherein the second attenuation map provides maximum likelihood of the PET sinogram data within a field of view of the PET unit including all parts not within the field of view of the MR scanner.

5. The method of claim 1, wherein the producing the attenuation map includes,

generating a model,

parameterizing the model by model parameters, and

creating the parameterized model instance based on the acquired PET sinogram data and the parameterized model.

6. The method of claim 5, wherein the model is a statistical model.

7. The method of claim 6, wherein the parameterizing the statistical model includes parameterizing the statistical model by deformation parameters, attenuation parameters and affine parameters.

8. The method of claim 6, wherein the generating the statistical model includes performing principal component analysis of deformation fields and attenuation maps resulting from coregistrations of example data sets.

9. The method of claim 1, wherein the producing the attenuation map includes,

generating a model, and

adapting the model to an initial attenuation map, the parameterized model instance being created based on the adapted model.

10. The method of claim 1, wherein the PET unit is configured to acquire the PET sinogram data.

11. The method of claim 1, wherein a computer connected to the MR scanner and the PET unit is configured to produce the attenuation map.

12. A computer-readable medium, when run on a computer, configured to instruct the computer to perform the method of claim 1.

13. A method of correcting attenuation in a magnetic resonance (MR) scanner and a positron emission tomography (PET) unit, the method comprising:

acquiring PET sinogram data of an object within a field of view of the PET unit;

acquiring MR data of the object within a field of view of the MR scanner;

producing an attenuation map based on a maximum likelihood expectation maximization (MLEM) of a parameterized model instance and the acquired PET sinogram and MR data, the MLEM being constrained by model parameters of the parameterized model instance.

14. The method of claim 13, wherein the producing the attenuation map includes producing a PET attenuation map.

15. The method of claim 14, wherein the producing the PET attenuation map includes,

generating a model,

parameterizing the model by the model parameters, and

creating the parameterized model instance based on the parameterized model.

16. The method of claim 15, wherein the model is a statistical model.

17. The method of claim 16, wherein the model parameters are the deformation parameters and the attenuation appearance parameters.

18. The method of claim 17, wherein the model parameters further include affine parameters.

19. The method of claim 14, further comprising:

producing an MR attenuation map.

20. The method of claim 13, wherein the producing the attenuation map includes,

generating a model, and

adapting the model to an initial attenuation map, the parameterized model instance being created based on the adapted model.

21. The method of claim 13, wherein the PET unit is configured to acquire the PET sinogram data.

22. The method of claim 13, wherein a computer connected to the MR scanner and the PET unit is configured to produce the attenuation map.

23. The method of claim 13, wherein the MR scanner is configured to acquire the MR data.

24. A computer-readable medium, when run on a computer, configured to instruct the computer to perform the method of claim 13.

25. A device comprising:

a positron emission tomography (PET) unit including a plurality of detection units and configured to acquire PET sinogram data of an object within a field of view of the PET unit;

a magnetic resonance (MR) scanner configured to acquire MR data of the object within a field of view of the MR scanner; and

a computer configured to produce an attenuation map based on a maximum likelihood expectation maximization (MLEM) of a parameterized model instance and the acquired PET sinogram and MR data, the MLEM being constrained by model parameters of the parameterized model instance.