Using the UMLS Semantic Network to validate NCI Thesaurus structure and analyze its alignment with the OBO relations ontology.

NCI Thesaurus entries reference corresponding nodes in the UMLS Semantic Network (SN). Adapting a process previously used to refine relationship definitions in the UMLS Metathesaurus, we used these Thesaurus-to-Network references to analyze alignment of the Thesaurus with the OBO Relations Ontology and at the same time validate and improve Thesaurus structure. Given this experience, we offer suggestions for enhancement of the UMLS SN so that it can be even more useful in the future.