X-ray diagnostic apparatus and image processing apparatus

1. An X-ray diagnostic apparatus comprising:

an X-ray generator configured to irradiate a plurality of X-rays to a subject;

an X-ray detector configured to detect the plurality of X-rays;

processing circuitry configured to

generate a first plurality of X-ray images chronologically based on the plurality of X-rays that have passed through the subject into which a contrast media is injected, and that have been detected by the X-ray detector,

calculate, for the first plurality of X-ray images, a differential value obtained by subtracting a pixel value in a region of a latter image from a pixel value in a region of a former image in chronologically sequential two images, respectively,

extract, from the first plurality of X-ray images, a second plurality of X-ray images subsequent to the latter image for which the calculated differential value is a positive value,

extract a first image from among the second plurality of X-ray images, the first image being a former image in which the calculated differential value is equal to or smaller than a threshold, and

sequentially generate a plurality of emphasized images by sequentially performing trace processing or signal averaging processing on two or more X-ray images from the latter image for which the calculated differential value is the positive value to the first image in reverse chronological order; and

a display configured to display the plurality of emphasized images in order in which the plurality of emphasized images were generated.

2. The X-ray diagnostic apparatus according to claim 1 , wherein the processing circuitry is further configured to be operated by an operator, wherein

the display is configured to display the plurality of emphasized images based on operation by the operator.

3. The X-ray diagnostic apparatus according to claim 1 , wherein the display is configured to display the plurality of emphasized images as a moving image.

4. The X-ray diagnostic apparatus according to claim 1 , wherein the trace processing is processing for extracting a largest pixel value for each pixel in the two or more X-ray images, and the signal averaging processing is processing for signal averaging the two or more X-ray images.

5. The X-ray diagnostic apparatus according to claim 1 , wherein the processing circuitry is further configured to extract a region in which the contrast media remains, based on analysis of a pixel value distribution in an emphasized image of the plurality of emphasized images, or number of inflection points in a profile of the emphasized image.

6. The X-ray diagnostic apparatus according to claim 5 , wherein the processing circuitry is configured to extract the region in which the contrast media remains by calculating a profile of a stent end region in the emphasized image.

7. The X-ray diagnostic apparatus according to claim 5 , wherein the display is configured to display, in the emphasized image, a mark that indicates the region in which the contrast media remains.

8. An image processing apparatus comprising:

processing circuitry configured to

generate a first plurality of X-ray images chronologically based on X-rays that have passed through a subject into which a contrast media is injected,

calculate, for the first plurality of X-ray images, a differential value obtained by subtracting a pixel value in a region of a latter image from a pixel value in a region of a former image in chronologically sequential two images, respectively,

extract, from the first plurality of X-ray images, a second plurality of X-ray images subsequent to the latter image for which the calculated differential value is a positive value,

extract a first image from among the second plurality of X-ray images, the first image being a former image in which the calculated differential value is equal to or smaller than a threshold, and

sequentially generate a plurality of emphasized images by sequentially performing trace processing or signal averaging processing on two or more X-ray images from the latter image for which the calculated differential value is the positive value to the first image in reverse chronological order; and

a display configured to display the plurality of emphasized images in order in which the plurality of emphasized images were generated.

9. An image processing method comprising:

generating a first plurality of X-ray images chronologically based on X-rays that have passed through a subject into which a contrast media is injected;

calculating, for the first plurality of X-ray images, a differential value obtained by subtracting a pixel value in a region of a latter image from a pixel value in a region of a former image in chronologically sequential two images, respectively;

extracting, from the first plurality of X-ray images, a second plurality of X-ray images subsequent to the latter image for which the calculated differential value is a positive value;

extracting a first image from among the second plurality of X-ray images, the first image being a former image in which the calculated differential value is equal to or smaller than a threshold;

sequentially generating a plurality of emphasized images by sequentially performing trace processing or signal averaging processing on two or more X-ray images from the latter image for which the calculated differential value is the positive value to the first image in reverse chronological order; and

displaying the plurality of emphasized images in order in which the plurality of emphasized images were generated.