Medical image diagnostic apparatus

1. A medical image diagnostic apparatus comprising:

processing circuitry that

estimates a position of a plaque in a blood vessel based on data of a plurality of CT images constituting a time series, with the blood vessel being enhanced by a contrast medium,

estimates hardness of the plaque based on a CT value at the position, extracts a plurality of regions constituting the blood vessel from the plurality of CT images,

specifies a plurality of stress values respectively corresponding to the plurality of regions constituting the blood vessel based on a moving displacement due to cardiac pulsation in each of the regions constituting the blood vessel,

specifies an exfoliation risk of the plaque based on the estimated hardness and a stress value, of the plurality of stress values, in a region corresponding to the position, and

generates a color map of the stress values along a blood vessel contour of the blood vessel included in a CT image of the plurality of CT images by generating a stress value distribution chart and converting the stress value distribution chart into the color map; and

a display that

displays the CT image of the plurality of CT images,

displays a mark indicating (i) a position of a first plaque such that the mark is superimposed on the CT image and (ii) a priority order of a medical treatment of the first plaque or whether the medical treatment is necessary based on the specified exfoliation risk of the first plaque,

displays display information indicating a degree of the estimated hardness of the first plaque for the mark, and

displays the generated color map of the stress values along the blood vessel contour included in the CT image superimposed on the mark indicating the first plaque, wherein

the displayed CT image is a two-dimensional long-axis sectional image of the blood vessel, and

the display superimposes the mark and the generated color map on the two-dimensional long-axis sectional image.

2. The medical image diagnostic apparatus according to claim 1 , wherein the display information is a color or pattern of the mark that indicates the degree of the hardness corresponding to the first plaque.

3. The medical image diagnostic apparatus according to claim 1 , wherein the display displays the mark in color or shape corresponding to the first plaque.

4. The medical image diagnostic apparatus according to claim 1 , wherein the display displays a text indicating the degree of the hardness corresponding to the first plaque.

5. The medical image diagnostic apparatus according to claim 1 , wherein the display displays a text indicating a degree of the stress value in the region corresponding to the position of the first plaque.

6. The medical image diagnostic apparatus according to claim 1 , wherein

the display displays an icon for switching a display mode, and

the processing circuitry, in response to an input via the icon, switches the display mode between displaying the CT image, the mark, and the generated color map.

7. The medical image diagnostic apparatus according to claim 1 , wherein the display displays the CT image, the mark, the display information indicating the degree of the hardness, the generated color map of the stress value along the blood vessel contour, a color bar, and an annotation indicating the degree of the stress value and a degree of pressure.

8. A medical image diagnostic method comprising:

estimating, by processing circuitry, a position of a plaque in a blood vessel based on data of a plurality of CT images constituting a time series, with the blood vessel being enhanced by a contrast medium;

estimating, by the processing circuitry, hardness of the plaque based on a CT value at the position;

extracting, by the processing circuitry, a plurality of regions constituting the blood vessel from the plurality of CT images;

specifying, by the processing circuitry, a plurality of stress values respectively corresponding to the plurality of regions constituting the blood vessel based on a moving displacement due to cardiac pulsation in each of the regions constituting the blood vessel;

specifying, by the processing circuitry, an exfoliation risk of the plaque based on the estimated hardness and a stress value, of the plurality of stress values, in a region corresponding to the position;

generating, by the processing circuitry, a color map of the stress values along a blood vessel contour of the blood vessel included in a CT image of the plurality of CT images by generating a stress value distribution chart and converting the stress value distribution chart into the color map; and

displaying, on a display,

the CT image of the plurality of CT images,

a mark indicating (i) a position of a first plaque such that the mark is superimposed on the CT image and (ii) a priority order of a medical treatment of the first plaque or whether the medical treatment is necessary based on the specified exfoliation risk of the first plaque,

display information indicating a degree of the estimated hardness of the first plaque for the mark, and

the generated color map of the stress values along the blood vessel contour included in the CT image superimposed on the mark indicating the first plaque, wherein

the displayed CT image is a two-dimensional long-axis sectional image of the blood vessel, and

the displaying superimposes the mark and the generated color map on the two-dimensional long-axis sectional image.