MRI apparatus, method and process generating diffusion weighted images using apparent diffusion coefficients and threshold values

1. A magnetic resonance imaging apparatus comprising:

a unit which generates a diffusion weighted image based on a magnetic resonance signal from an object;

a unit which calculates an apparent diffusion coefficient based on the diffusion weighted image; and

a processing unit which subjects the diffusion weighted image to a process of indicating a region having the apparent diffusion coefficient of less than a threshold value with a highlight in contrast with at least one other region of the diffusion weighted image.

2. The magnetic resonance imaging apparatus according to claim 1 , further comprising:

a setting unit which sets a value assigned arbitrarily by an operator as the threshold value.

3. The magnetic resonance imaging apparatus according to claim 2 , wherein the processing unit, when a new threshold value is set by the setting unit, subjects the diffusion weighted image to the process using the new threshold value.

4. The magnetic resonance imaging apparatus according to claim 1 , wherein the processing unit further comprising:

a low-value region image generating unit which generates a low-value region image that indicates a region where the apparent diffusion coefficient is less than the threshold value in the diffusion weighted image; and

a superimposing unit which superimposes the low-value region image onto the diffusion weighted image.

5. The magnetic resonance imaging apparatus according to claim 1 , wherein the low-value region image generating unit generates the low-value region image in such a way that the region where the apparent diffusion coefficient is less than the threshold value in the diffusion weighted image is tinted with a different color from that of the diffusion weighted image.

6. The magnetic resonance imaging apparatus according to claim 4 , wherein:

the low-value region image generating unit generates the low-value region image after binarizing the diffusion weighted image with the threshold value, and

the superimposing unit subjects the diffusion weighted image to a masking process based on the low-value region image.

7. The magnetic resonance imaging apparatus according to claim 4 , wherein the processing unit carries out a maximum intensity projection process on superimposed images obtained from a plurality of slices of diffusion weighted image and respective low-value region images.

8. The magnetic resonance imaging apparatus according to claim 4 , wherein:

the low-value region image generating unit generates a plurality of low-value region images using a plurality of threshold values, and

the superimposing unit superimposes each of the plurality of low-value region images to the diffusion weighted image.

9. An image processing apparatus usable with magnetic resonance imaging comprising:

a first memory unit which stores a diffusion weighted image of an object;

a second memory unit which stores an apparent diffusion coefficient image related to the diffusion weighted image; and

a processing unit which subjects the diffusion weighted image to a process of indicating a region having an apparent diffusion coefficient of less than a threshold value with a highlight in contrast with at least one other region of the diffusion weighted image.

10. A magnetic resonance imaging method comprising the steps of:

generating a diffusion weighted image based on a magnetic resonance signal from an object;

calculating an apparent diffusion coefficient based on the diffusion weighted image; and

subjecting the diffusion weighted image to a process of indicating a region having the apparent diffusion coefficient of less than a threshold value with a highlight in contrast with at least one other region of the diffusion weighted image.