Aligning knowledge sources in the UMLS: methods, quantitative results, and applications.

The UMLS Semantic Network and Metathesaurus are two complementary knowledge sources. While many studies compare relationships across the two structures, their alignment has never been attempted. We applied two methods based on lexical and conceptual similarity to aligning the Semantic Network with the UMLS Metathesaurus. Approximately two thirds of the semantic types could be aligned by lexical similarity. Conceptual similarity suggested mappings in all but ten cases. Potential applications enabled by the alignment are discussed, namely auditing the consistency between the Semantic Network and the Metathesaurus and extending the Semantic Network downwards. The relative contribution and limitations of the two methods used for the alignment are also discussed.