2. UNIFIED MEDICAL LANGUAGE SYSTEMS (UMLS)
The Unified Medical Language System (UMLS) is a long term research and development project that started in 1986 by the U.S. National Library of Medicine (NLM)
The UMLS is not a gigantic and comprehensive medical vocabulary
The UMLS is a relational database connecting “by concept” over 60 vocabularies, thesauri, medical problem lists etc.
The UMLS project is development effort designed to facilitate the retrieval and integration of information from multiple machine-readable biomedical information sources, furthermore, helping to health professionals and researchers from using available machine-readable information in the way concepts are expressed in different machine-readable sources and by different users. The goal is to make it easier to develop systems that link information from patient record systems, bibliographic databases, factual databases, expert systems and the lexical programs in natural language processing and indexing research.

3. Purpose
To aid the development of systems that help health professionals and researchers retrieve and integrate electronic biomedical information form a variety of sources, such as:
Computer-based Patient Records
Bibliographic databases
Factual (full text) databases
Administrative health data
Expert systems

4. UMLS Uses Electronic patient records Natural language processing
Information retrieval
Thesaurus construction
Automated indexing

5. UMLS COMPONENTS
Metathesaurus
Semantic Network
Lexicon

6. UMLS Source “Vocabularies”
Widely varying purposes, structures, properties that do not add up to single ontology or view of the world:
Thesauri, e.g., MeSH (Medical Subject Headings)
Statistical Classifications, e.g., ICD
Billing Codes, e.g., CPT
Clinical coding systems, e.g., SNOMED
Lists of controlled terms, e.g., HL7 valid values

7. How to combine them? Not reallly ...
Concepts, terms and attributes from many controlled vocabularies.
New inter-source relationships, definitional information, use information.
Scope determined by combined scope of source vocabularies.

8. METATHESAURUS Contains more than 60 vocabularies and classifications.
concepts
2,1 millions of concept names
11 millions of relationships between concepts
Concepts, terms and attributes from many controlled “vocabularies”
New inter-source relationships, definitional information, use information.
Scope determined by combined scope of source vocabularies

9. Metathesaurus - Relations
Preserves the structure of the original sources.
Add news relationships between the concepts

10. METATHESAURUS Organization
CUI
Synonymous terms
Preferred term

11. Metathesaurus structure
CONCEPTs
TERMs
STRING
CUI’s
LUI’s
SUI’s
STRING
Is organized by concept or meaning; its purpose is to link alternative names and views of the same concept together and to identify useful relationships between different concepts..
The Metathesaurus preserves the meanings, hierarchical connections, and other relationships between terms present in its source vocabularies, while adding certain basic information about each of its concepts and establishing new relationships between concepts and terms from different source vocabularies.
STRING
STRING

12. Metathesaurus structure example
CONCEPTS
(CUIs)
TERMS
(LUIs)
STRING
(SUIs) C L S
(preferred)
Atrial Fibrillation
Atrial Fibrillations
Auricular Fibrillation
Auricular Fibrillations S L S
(synonym)
Auricular Fibrillation(preferred) S
(plural variant)

13. Semantic Network
All information about specific concepts is found in the Metathesaurus
The Network provides information about the basic semantic types that are assigned to these concepts, and it defines the relationships that may hold between the semantic types
It defines these types, both with textual descriptions and by means of the information inherent in its hierarchies

14. Semantic Network Example “BIOLOGIC FUNTION” HIERARCHY
EXPERIMENTAL
MODEL OF
DISEASE
The semantic types are the nodes in the Network, and the relationships between them are the link and that are assigned to concepts in the Metathesaurus.
The current scope of the UMLS semantic types is quite broad, allowing for the semantic categorization of a wide range of terminology in multiple domains.

15. Relationship between Metathesaurus and Semantic Network

16. LEXICON
It provide the lexical information needed for the SPECIALIST Natural Language Processing System
It is a general English lexicon that includes many biomedical terms (commonly occurring English words and biomedical vocabulary)
The lexicon entry for each word (or term) records the
syntactic
morphological
orthographic information needed by the SPECIALIST natural language processing system
The lexicon consists of a set of lexical entries with one entry for each spelling or set of spelling variants in a particular part of speech. Lexical items may be “multi-word” terms made up of other words if the multi-word term is determined to be a lexical item by its presence as a term in general English or medical dictionaries, or in medical thesauri. Expansions of generally used acronyms and abbreviations are also allowed as multi-word terms.
The lexicon record format has one record per entry. When a base form has more than one part of speech there will be more than one record for that base form.

17. UNIFIED MEDICAL LANGUAGE SYSTEM - Summary
Standard source of concepts and synonyms.
Multilingual
Broad extension.
Allow integration between applications

18. REFERENCES http://www.nlm.nih.gov/pubs/factsheets/umls.html