PROBLEM TO BE SOLVED: To omit the operation for manually specifying a region of subcutaneous fat on an image for obtaining a mean CT value of a patient and a standard deviation. SOLUTION: A region of a fat CT value range determined from general CT value distribution of fat is cut out of an image (S2), the mean CT value (Mean) of the cutout region and the standard deviation (SD) are computed (S3), an upper limit CT threshold u=Mean+k×SD and a lower limit CT threshold d=Mean-k×SD for extracting a fat region are computed (S4), a peritoneum region is specified by an operator (S5), and a region in a CT value range between the upper CT threshold u and the lower CT threshold d is extracted from the peritoneum region and displayed (S6). Thus, the labor for the diagnosis operation for visceral adiposis can be saved.
