Biomedical Retrieval: How Can a Thesaurus Help?

Searching specialized collections, such as biomedical literature, typically requires intimate knowledge of a specialized terminology. Hence, it can be a disappointing experience: not knowing the right terms to use and being unaware of synonyms or variations in terminology might result in low recall scores. We study the role of a thesaurus in the biomedical information retrieval process. We start by giving a description of vocabulary mismatch problems between natural language queries and relevant documents in biomedical literature search; we provide a detailed case study and observe the impact of vocabulary mismatch problems on retrieval effectiveness. Additionally, we analyze the associated MeSH thesaurus terms used to index the documents in the collection. Based on our observations, we propose a method for exploiting the MeSH thesaurus to improve retrieval effectiveness and, more specifically, to increase recall. We carry out a series of thesaurus-based retrieval experiments that show substantial performance improvements. We conclude with a detailed analysis of the retrieval results.