Blood vessel image processing apparatus, blood vessel image processing program, and blood vessel image processing method

A non-transitory computer readable medium storing a blood vessel image processing program for causing a computer to execute

• a center line specifying process of specifying a center line of a blood vessel based on three-dimensional blood vessel data showing a three-dimensional shape of the blood vessel;
• a protruding portion center line specifying process of specifying, as a protruding portion center line, a center line of a protruding portion of the blood vessel from the center line specified by the center line specifying unit;
• a branched center line specifying process of specifying, as a branched center line, a center line branched from the protruding portion center line specified by the protruding portion center line specifying unit;
• a conversion process of defining, for the three-dimensional blood vessel data of the blood vessel corresponding to the branched center line specified by the branched center line specifying unit, a cylindrical coordinate system using, as coordinate axes, a blood vessel circumferential direction about the branched center line, a blood vessel radial direction from the branched center line, and a direction of the branched center line, thereby converting the blood vessel data of the blood vessel corresponding to the branched center line in the cylindrical coordinate system into blood vessel data in an orthogonal coordinate system;
• an interpolation process of interpolating a coordinate value of the coordinate axis in the blood vessel radial direction between a first coordinate value and a second coordinate value, by using the blood vessel data converted into the orthogonal coordinate system by the conversion unit, each of the first coordinate value and the second coordinate value being a coordinate value of the coordinate axis in the direction of the branched center line;
• using the interpolated coordinate value to delete the protruding portion;
• an inverse conversion process of converting, after interpolation by the interpolation unit, the blood vessel data in the orthogonal coordinate system into blood vessel data in the cylindrical coordinate system to generate normal main vessel voxel data;
• and
• calculating a difference image between the three-dimensional blood vessel data and the normal main vessel voxel data to generate three-dimensional data of the protruding portion:
• a display process of displaying the blood vessel data converted in the cylindrical coordinate system by the inverse conversion unit or the calculated difference image,
• wherein, at the protruding portion center line specifying process, a branching point at which the center line specified by the center line specifying process is branched is specified and a center line not having the branching point at least at one end is specified as the protruding portion center line,
• specifies, as a length of the center line, a length from the branching point to a point at which the center line is disconnected, and
• excludes a center line with a value equal to or less than a predetermined threshold to specify the protruding portion of the blood vessel, the value being obtained in such a manner that the specified length of the center line is divided by a radius from the center line to an outer periphery of the blood vessel.

A computer-implemented method for processing blood vessel image, comprising:

• a step of causing a center line specifying unit to specify a center line of a blood vessel based on three-dimensional blood vessel data showing a three-dimensional shape of the blood vessel;
• a step of causing a protruding portion center line specifying unit to specify, as a protruding portion center line, a center line of a protruding portion of the blood vessel from the center line specified by the center line specifying unit;
• a step of causing a branched center line specifying unit to specify, as a branched center line, a center line branched from the protruding portion center line specified by the protruding portion center line specifying unit;
• a step of causing a conversion unit to define, for the three-dimensional blood vessel data of the blood vessel corresponding to the branched center line specified by the branched center line specifying unit, a cylindrical coordinate system using, as coordinate axes, a blood vessel circumferential direction about the branched center line, a blood vessel radial direction from the branched center line, and a direction of the branched center line, thereby converting the blood vessel data of the blood vessel corresponding to the branched center line in the cylindrical coordinate system into blood vessel data in an orthogonal coordinate system;
• a step of causing an interpolation unit to interpolate a coordinate value of the coordinate axis in the blood vessel radial direction between a first coordinate value and a second coordinate value, by using the blood vessel data converted into the orthogonal coordinate system by the conversion unit, each of the first coordinate value and the second coordinate value being a coordinate value of the coordinate axis in the direction of the branched center line;
• using the interpolated coordinate value to delete the protruding portion;
• a step of causing an inverse conversion unit to convert, after interpolation by the interpolation unit, the blood vessel data in the orthogonal coordinate system into blood vessel data in the cylindrical coordinate system to generate normal main vessel voxel data;
• and
• calculating a difference image between the three-dimensional blood vessel data and the normal main vessel voxel data to generate three-dimensional data of the protruding portion;
• a step of causing a display unit to display the blood vessel data converted in the cylindrical coordinate system by the inverse conversion unit or the calculated difference image,
• wherein the step of causing a branched center line specifying unit to specify includes specifying a branching point at which the center line specified by the center line specifying unit is branched, and specifying, as the protruding portion center line, a center line not having the branching point at least at one end,
• specifies, as a length of the center line, a length from the branching point to a point at which the center line is disconnected, and
• excludes a center line with a value equal to or less than a predetermined threshold to specify the protruding portion of the blood vessel, the value being obtained in such a manner that the specified length of the center line is divided by a radius from the center line to an outer periphery of the blood vessel.