A system for accessing a database comprising a plurality of image data sets, the system comprising: an acquiring unit for acquiring a query for searching the database for an image data set or an image data subset comprised in an image data set, the query comprising at least one medically relevant term defining search criteria, the medical term being extracted by an extracting unit; a segmenting unit for segmenting an image data set in the database into a plurality of image data subsets by adapting annotated shape models, using model-based segmentation, and generating for each of the image data subsets anatomical identifiers and associated annotations describing the image data set, using corresponding annotated shape models for adaptation; a generating unit for generating an anatomical annotation for the image data set, based on measures of anatomical structures in the regions identified by at least one corresponding anatomical identifier of at least one image data subset of the image data set and computation of two measures thereof; an anchoring unit for anchoring the at least one extracted medically relevant term and the at least one medical annotation into a medical ontology, the anchoring based on lexical similarity measures of the at least one extracted medically relevant term and the at least one medical annotation to concept labels present in a medical ontology; a determining unit for determining the image data set or the image data subset comprised in the image data set, based on the strength of semantic matches between the at least one medically relevant term and the at least one corresponding medical annotation describing the image data set; wherein the strength is derived by a reasoning process provided in terms of a number of relations in a path between anchors in a medical ontology corresponding to the term and the annotation, and a retrieving unit for retrieving the determined image data set or image data subset from the database. an acquiring unit for acquiring a query for searching the database for an image data set or an image data subset comprised in an image data set, the query comprising at least one medically relevant term defining search criteria, the medical term being extracted by an extracting unit; a segmenting unit for segmenting an image data set in the database into a plurality of image data subsets by adapting annotated shape models, using model-based segmentation, and generating for each of the image data subsets anatomical identifiers and associated annotations describing the image data set, using corresponding annotated shape models for adaptation; a generating unit for generating an anatomical annotation for the image data set, based on measures of anatomical structures in the regions identified by at least one corresponding anatomical identifier of at least one image data subset of the image data set and computation of two measures thereof; an anchoring unit for anchoring the at least one extracted medically relevant term and the at least one medical annotation into a medical ontology, the anchoring based on lexical similarity measures of the at least one extracted medically relevant term and the at least one medical annotation to concept labels present in a medical ontology; a determining unit for determining the image data set or the image data subset comprised in the image data set, based on the strength of semantic matches between the at least one medically relevant term and the at least one corresponding medical annotation describing the image data set; wherein the strength is derived by a reasoning process provided in terms of a number of relations in a path between anchors in a medical ontology corresponding to the term and the annotation, and a retrieving unit for retrieving the determined image data set or image data subset from the database.