1. An apparatus for providing additional information for region of interest, the apparatus comprising: at least one processor configured to: extract at least one region of interest from a first medical image, extract at least one region of interest from each of at least one second medical image, merge the at least one region of interest extracted from each of the at least one second medical image into the first medical image, determine additional information needed for a diagnosis of each of the at least one region of interest merged into the first medical image by retrieving at least one rule for the merged at least one region of interest from at least one pre-stored rule, and selecting the additional information based on the retrieved at least one rule, and provide the determined additional information, wherein the determined additional information comprises at least one of: new additional information that refers to information associated with examinations to be additionally conducted for an accurate diagnosis, or previous additional information that refers to examination-related information pre-stored in a medical database to be additionally provided for an accurate diagnosis.