An apparatus for processing a medical image, the apparatus comprising a processor configured to: set, among a plurality of 2-dimensional image frames that form a 3-dimensional image, at least two sections including a first section and a second section; extract, among the plurality of 2-dimensional image frames that form the 3-dimensional image, at least two reference image frames usable for processing a boundary of at least one lesion, wherein the at least two reference image frames include a first reference image frame extracted from the first section and a second reference image frame extracted from the second section; set, in the first reference image frame and in the second reference image frame, respective boundaries of at least one lesion based on pixel values in each reference image frame that represent a characteristic of a lesion included in the first reference image frame and the second reference image frame; set, in at least one adjacent preceding image frame and in at least one adjacent successive image frame relative to the first reference image frame in the first section, a boundary of at least one lesion based on a respective pixel value of the first reference image frame; set, in at least one adjacent preceding image frame and in at least one adjacent successive image frame relative to the second reference image frame in the second section, a boundary of at least one lesion based on a respective pixel value of the second reference image frame; receive an input to adjust the set boundaries of the at least one lesion designating another boundary of the at least one lesion in the first reference image frame and the second reference image frame; display adjusted set boundaries of at least one lesion in the first reference image frame and the second reference image frame; and adapt the adjacent preceding image frames and the adjacent successive image frames of the first and second sections to the adjusted set boundaries of the at least one lesion in the first reference image frame and the second reference image frame, respectively. set, among a plurality of 2-dimensional image frames that form a 3-dimensional image, at least two sections including a first section and a second section; extract, among the plurality of 2-dimensional image frames that form the 3-dimensional image, at least two reference image frames usable for processing a boundary of at least one lesion, wherein the at least two reference image frames include a first reference image frame extracted from the first section and a second reference image frame extracted from the second section; set, in the first reference image frame and in the second reference image frame, respective boundaries of at least one lesion based on pixel values in each reference image frame that represent a characteristic of a lesion included in the first reference image frame and the second reference image frame; set, in at least one adjacent preceding image frame and in at least one adjacent successive image frame relative to the first reference image frame in the first section, a boundary of at least one lesion based on a respective pixel value of the first reference image frame; set, in at least one adjacent preceding image frame and in at least one adjacent successive image frame relative to the second reference image frame in the second section, a boundary of at least one lesion based on a respective pixel value of the second reference image frame; receive an input to adjust the set boundaries of the at least one lesion designating another boundary of the at least one lesion in the first reference image frame and the second reference image frame; display adjusted set boundaries of at least one lesion in the first reference image frame and the second reference image frame; and adapt the adjacent preceding image frames and the adjacent successive image frames of the first and second sections to the adjusted set boundaries of the at least one lesion in the first reference image frame and the second reference image frame, respectively.