A contour segmentation apparatus comprising: a display; a memory configured to store instructions; and at least one processor, that upon executing the stored instructions, configured to: display, on the display, a medical image comprising at least one region of interest; extract a region contour of the at least one ROI comprised in the medical image using a contour segment algorithm; control the display to display the extracted region contour on the medical image; and modify at least one portion of the region contour based on a mode selected by a user from two or more modes for modifying the region contour, and an operation performed by the user, wherein the at least one processor is further configured to: adjust, in response to detecting a first input inside of the region contour, a threshold value of the contour segmentation algorithm higher than a previous threshold value such that the at least one portion of the region contour is moved inward of the region contour; and adjust, in response to detecting a second input outside of the region contour, the threshold value of the contour segmentation algorithm lower than the previous threshold value such that the at least one portion of the region contour is moved outward of the region contour. a display; a memory configured to store instructions; and at least one processor, that upon executing the stored instructions, configured to: display, on the display, a medical image comprising at least one region of interest; extract a region contour of the at least one ROI comprised in the medical image using a contour segment algorithm; control the display to display the extracted region contour on the medical image; and modify at least one portion of the region contour based on a mode selected by a user from two or more modes for modifying the region contour, and an operation performed by the user, wherein the at least one processor is further configured to: adjust, in response to detecting a first input inside of the region contour, a threshold value of the contour segmentation algorithm higher than a previous threshold value such that the at least one portion of the region contour is moved inward of the region contour; and adjust, in response to detecting a second input outside of the region contour, the threshold value of the contour segmentation algorithm lower than the previous threshold value such that the at least one portion of the region contour is moved outward of the region contour. display, on the display, a medical image comprising at least one region of interest; extract a region contour of the at least one ROI comprised in the medical image using a contour segment algorithm; control the display to display the extracted region contour on the medical image; and modify at least one portion of the region contour based on a mode selected by a user from two or more modes for modifying the region contour, and an operation performed by the user, adjust, in response to detecting a first input inside of the region contour, a threshold value of the contour segmentation algorithm higher than a previous threshold value such that the at least one portion of the region contour is moved inward of the region contour; and adjust, in response to detecting a second input outside of the region contour, the threshold value of the contour segmentation algorithm lower than the previous threshold value such that the at least one portion of the region contour is moved outward of the region contour.