Ultrasound diagnosis apparatus

1. An ultrasound diagnosis apparatus, comprising:

an image generator configured to execute transmission and reception of ultrasound waves to chronologically generate ultrasound image data of plural frames;

a multiresolution decomposition part configured to hierarchically execute multiresolution decomposition on the ultrasound image data of plural frames to obtain first-order to n th -order (n represents a natural number of 2 or more) low-band decomposition image data and first-order to n th -order high-band decomposition image data;

a feature amount calculator configured to calculate a feature amount based on the obtained low-band decomposition image data;

a filtering processor configured to execute a filter operation on the calculated feature amount of ultrasound image data which becomes a filtering processing object based on a feature amount calculated by ultrasound image data of plural frames imaged at time prior to a time at which a frame of the ultrasound image data is imaged; and

a multiresolution composition part configured to execute multiresolution composition by using the low-band decomposition image data and the high-band decomposition image data to generate a composite image.

2. The ultrasound diagnosis apparatus according to claim 1 , further comprising a data accumulator configured to store the ultrasound image data, wherein the filtering processor is configured to, as a filtering process on ultrasound image data of a t th frame among the plural frames, numerically analyze a diffusion equation by using pixel values of pixels at a same position in ultrasound image data of each of frames of a predetermined number of frames back from a (t−1) th frame stored in the data accumulator to calculate pixel values of respective pixels at the same position in ultrasound image data of the t th frame.

3. The ultrasound diagnosis apparatus according to claim 1 , further comprising a data accumulator configured to store the low-band decomposition image data, wherein the filtering processor is configured to, as a filtering process on ultrasound image data of a t th frame, numerically analyze a diffusion equation by using pixel values of pixels at a same position in low-band decomposition image data of each of frames of a predetermined number of frames back from a (t−1) th frame stored in the data accumulator to calculate pixel values of respective pixels at the same position in processed low-band decomposition image data of the t th frame.

4. The ultrasound diagnosis apparatus according to claim 1 , wherein:

the filtering processor is configured to use a filter expressed by a nonlinear diffusion equation; and

in the case of execution of numerical analysis of the nonlinear diffusion equation,

∂ I i /∂x={I i+1 −I i−1 }/2

is used as numerical differentiation in a spatial direction and

∂ I t /∂t={ 3 I t −4 I t−1 −I t−2 }/2

is used as numerical differentiation in a temporal direction, wherein I i represents a pixel value when x is i and I t represents a pixel value at time t.

5. The ultrasound diagnosis apparatus according to claim 1 , wherein the feature amount calculator is configured to calculate a structure tensor of each pixel, calculate eigenvalues and eigenvectors by using the structure tensor, and calculate a feature amount by using the eigenvalues and the eigenvectors.

6. The ultrasound diagnosis apparatus according to claim 1 , wherein the filtering processor is configured by a nonlinear anisotropic diffusion filter.

7. The ultrasound diagnosis apparatus according to claim 1 , further comprising a high-band-level controller configured to execute a filtering process of emphasizing an edge on the high-band decomposition image data and output the processed high-band decomposition image data to the multiresolution composition part.

8. An ultrasound diagnosis apparatus, comprising:

an image generator configured to execute transmission and reception of ultrasound waves to chronologically generate ultrasound image data of plural frames;

a multiresolution decomposition part configured to hierarchically execute multiresolution decomposition on the ultrasound image data to obtain first-order to n th -order (n represents a natural number of 2 or more) low-band decomposition image data and first-order to n th -order high-band decomposition image data;

a multiresolution composition part configured to perform multiresolution composition by using the low-band decomposition image data and the high-band decomposition image data to generate a composite image;

a feature amount calculator configured to calculate a feature amount based on the obtained low-band decomposition image;

a filtering processor configured to perform a filter operation on the calculated feature amount of ultrasound image data which becomes a filtering processing object based on a feature amount calculated by ultrasound image data of plural frames imaged at time prior to time in which a frame of the ultrasound image data is imaged; and

a high-band-level controller configured to weight the first-order to n th -order high-band decomposition image data obtained from the multiresolution decomposition part, by a feature amount of each corresponding order.