PET-MRI device

1. A PET (Positron Emission Tomography)-MRI (Magnetic Resonance Imaging) device comprising:

a magnet configured to generate a static magnetic field within a bore of the PET-MRI, which is configured to accommodate a subject to be imaged;

a transmitting radio frequency coil configured to apply a radio frequency magnetic field on a target, which is arranged in the static magnetic field;

a gradient coil configured to apply a gradient magnetic field on the target;

a receiving radio frequency coil configured to detect a magnetic resonance (MR) signal emitted from the target resulting from an application of the radio frequency magnetic field and the gradient magnetic field on the target;

a first PET detector and a second PET detector each configured to have a right shape and detect annihilation radiation emitted from a positron-emitting radionuclide in the target; and

a processor configured to

capture an image of the target placed in an effective visual field of a PET and on a side edge portion of an effective visual field of an MRI by the PET and the MRI so as to generate a PET image and an MR image, the PET generating the PET image based on the annihilation radiation detected by the first PET detector and the second PET detector, the MRI generating the MR image based on the MR signal detected by the receiving radio frequency coil; and

derive a strain correction factor for correcting strain on the MR image based on a positional relation between a coordinate value of a position of the target represented on the PET image and a coordinate value of a position of the target represented on the MR image, wherein

the first PET detector and the second PET detector are adjustably configured with respect to each other to adjust an interval between the first PET detector and the second PET detector, and

the processor derives the strain correction factor for respective positions at which the first PET detector and the second PET detector are arranged.

2. The PET-MRI device according to claim 1 , the processor is further configured to correct the MR image by using the strain correction factor.

3. The PET-MRI device according to claim 1 , wherein the processor is configured to derive the strain correction factor based on the positional relation represented in the PET image and the MR image generated of the target, wherein the target is a phantom placed in the effective visual field of the PET and on the side edge portion of the effective visual field of the MRI as the target by the PET and the MRI.

4. The PET-MRI device according to claim 1 , wherein the processor is further configured to derive the strain correction factor based on the PET image and the MR image generated of the target, wherein the target has an arrangement position that changes as a function of position along a shaft direction of the bore on slice surfaces of the PET image and the MRI image.

5. The PET-MRI device according to claim 1 , wherein the processor is configured to derive the strain correction factor based on the positional relation represented in the PET image and the MR image generated of the target, wherein the target is a phantom incorporating a radioisotope and a hydrogen nucleus as the target by the PET and the MRI.

6. The PET-MRI device according to claim 1 , wherein the processor corrects strain on the MR image based on the positional relation between the target that is expressed on the PET image with no strain due to non-uniformity of a magnetostatic field and the target that is expressed on the MR image.

7. The PET-MRI device according to claim 1 , wherein the processor derives the strain correction factor for each pulse sequence of the MRI.

8. The PET-MRI device according to claim 1 , wherein the processor derives the strain correction factor by deriving a coordinate conversion matrix of coordinates of the target expressed on the PET image and coordinates of the target expressed on the MRI image.

9. The PET-MRI device according to claim 1 , wherein the processor is configured to derive the strain correction factor based on the positional relation represented in the PET image and the MR image generated of the target, wherein the target is a linear phantom extending in a shaft direction of the bore as the target by the PET and the MRI.

10. The PET-MRI device according to claim 9 , wherein the processor is configured to derive the strain correction factor based on the positional relation represented in the PET image and the MR image generated of the target, wherein the target is the linear phantom having a thickness within a spatial resolution of the PET by the PET and the MRI.

11. The PET-MRI device according to claim 1 , wherein the processor is configured to derive the strain correction factor based on the positional relation represented in the PET image and the MR image generated of the target, wherein the target is a dot-like phantom scattered in a shaft direction of the bore as the target by the PET and the MRI.

12. The PET-MRI device according to claim 11 , wherein the processor is configured to derive the strain correction factor based on the positional relation represented in the PET image and the MR image generated of the target, wherein the target is the dot-like phantom having a size within a spatial resolution of the PET by the PET and the MRI.

13. The PET-MRI device according to claim 11 , wherein the processor is further configured to derive the strain correction factor based on the PET image and the MR image generated of the target, wherein a spatial interval at which the dot-like phantom is scattered is identical to an interval at which images are captured by the PET and the MRI.