Apparatus, method, and program for detecting three dimensional abdominal cavity regions

1. A three dimensional abdominal cavity region extracting apparatus, comprising:

bone region extracting means, for extracting bone regions that represent the bones of a subject within a plurality of axial tomographic images including at least a first axial tomographic image that includes the ribs of the subject, a second axial tomographic image that includes the vicinity of the upper edge of the pelvis of the subject, and a third axial tomographic image that includes the vicinity of the pelvis of the subject lower than that which appears in the second axial tomographic image, obtained from a three dimensional image that represents a portion of the subject from the vicinity of the upper end of the liver to the vicinity of the pubic symphysis;

bone boundary point detecting means, for detecting a plurality of bone boundary points that represent the boundaries between the detected bone regions and regions positioned toward the interiors of the bone regions within the plurality of axial tomographic images; and

abdominal cavity region extracting means, for estimating curved surfaces within the three dimensional image that substantially contact the interiors of the plurality of bone boundary points detected in each of the plurality of axial tomographic images, based on the bone boundary points, and for extracting a three dimensional abdominal region surrounded by the curved surfaces as a three dimensional abdominal cavity region.

2. A three dimensional abdominal cavity region extracting apparatus as defined in claim 1 , further comprising:

diaphragm extracting means, for extracting diaphragm portions from at least one of the plurality of axial tomographic images and a plurality of axial tomographic images obtained from a three dimensional image that represents the thoracic region of the subject; wherein:

the abdominal cavity region extracting means extracts a region from within the three dimensional image surrounded by the curved surfaces and having the extracted diaphragm portions as the upper edge thereof as the three dimensional abdominal cavity region.

3. A three dimensional abdominal cavity region extracting apparatus as defined in claim 1 , further comprising:

body surface outline extracting means, for extracting the outline of the surface of the body of the subject from each of the plurality of axial tomographic images; wherein:

the abdominal cavity region extracting means estimates the curved surfaces such that the curved surfaces do not extend outside the exterior of the surface of the body.

4. A three dimensional abdominal cavity region extracting apparatus as defined in claim 1 , further comprising:

abdominal wall muscle outline extracting means, for extracting the outline of the exterior of the abdominal wall muscles of the subject from within each of the plurality of axial tomographic images; wherein:

the abdominal cavity region extracting means estimates the curved surfaces such that the curved surfaces do not extend outside the outline of the exterior of the abdominal wall muscles.

5. A three dimensional abdominal cavity region extracting apparatus as defined in claim 1 , further comprising:

visceral fat region discriminating means, for discriminating regions having pixel values that correspond to fat of the subject within the three dimensional abdominal cavity region extracted by the abdominal cavity region extracting means as three dimensional visceral fat regions.

6. A three dimensional abdominal cavity region extracting apparatus as defined in claim 1 , further comprising:

subcutaneous fat region discriminating means, for discriminating three dimensional subcutaneous fat regions within the three dimensional image, by discriminating subcutaneous fat regions that represent subcutaneous fat of the subject from within each of the plurality of axial tomographic images.

7. A three dimensional abdominal cavity region extracting apparatus as defined in claim 1 , wherein:

the bone boundary point detecting means sets search reference lines having end points at both sides of a line that bisects the subject in the horizontal direction at positions which are clearly anatomically in the abdominal cavity region within each of the plurality of axial tomographic images, such that the distances between the end points become shorter in axial tomographic images that represent lower portions of the subject, searches along a plurality of lines of sight that do not intersect and extend from a plurality of points along the search reference lines toward the exterior of the subject, and detects points that contact the bone regions first as the bone boundary points.

8. A three dimensional abdominal cavity region extracting method, comprising the steps of:

extracting bone regions that represent the bones of a subject within a plurality of axial tomographic images including at least a first axial tomographic image that includes the ribs of the subject, a second axial tomographic image that includes the vicinity of the upper edge of the pelvis of the subject, and a third axial tomographic image that includes the vicinity of the pelvis of the subject lower than that which appears in the second axial tomographic image, obtained from a three dimensional image that represents a portion of the subject from the vicinity of the upper end of the liver to the vicinity of the pubic symphysis;

detecting a plurality of bone boundary points that represent the boundaries between the detected bone regions and regions positioned toward the interiors of the bone regions within the plurality of axial tomographic images; and

estimating curved surfaces within the three dimensional image that substantially contact the interiors of the plurality of bone boundary points detected in each of the plurality of axial tomographic images, based on the bone boundary points; and

extracting a three dimensional abdominal region surrounded by the curved surfaces.

9. A non-transitory computer readable medium having stored therein a program that causes a computer to execute the procedures of:

extracting bone regions that represent the bones of a subject within a plurality of axial tomographic images including at least a first axial tomographic image that includes the ribs of the subject, a second axial tomographic image that includes the vicinity of the upper edge of the pelvis of the subject, and a third axial tomographic image that includes the vicinity of the pelvis of the subject lower than that which appears in the second axial tomographic image, obtained from a three dimensional image that represents a portion of the subject from the vicinity of the upper end of the liver to the vicinity of the pubic symphysis;

detecting a plurality of bone boundary points that represent the boundaries between the detected bone regions and regions positioned toward the interiors of the bone regions within the plurality of axial tomographic images; and

estimating curved surfaces within the three dimensional image that substantially contact the interiors of the plurality of bone boundary points detected in each of the plurality of axial tomographic images, based on the bone boundary points; and

extracting a three dimensional abdominal region surrounded by the curved surfaces.

10. A three dimensional abdominal cavity region extracting apparatus as defined in claim 1 , wherein:

the first axial tomographic image is an image that represents the vicinity of the upper edge of the liver of the subject.

11. A three dimensional abdominal cavity region extracting apparatus as defined in claim 1 , wherein:

the third axial tomographic image is an image that represents the vicinity of the pubic symphysis of the subject.