OIDM knowledge

Ontologies used

type: Referencestatus: draftgenerated by: claude-opus-5/claude-codegenerated at: 2026-09-21
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OIDM mints its own identifiers for two things only: finding models and their attributes, under the OIFM and OIFMA schemes. Everything else it points at. This page lists every external terminology that appears somewhere in the OIDM repositories, says who governs it, what its identifiers look like, which field carries it, and whether the molu lookup tool can resolve it.

Counts are from the corpus and datasets at the commits pinned in the sources. Finding model counts are occurrences of an index code across all 2,382 definitions, not distinct concepts.

TerminologyGoverned byIdentifier formWhere OIDM uses itResolved by molu
RadLexRSNARID plus digitsAnatomic location primary key; index codes on findings, attributes, valuesYes, RADLEX
SNOMED CTSNOMED InternationalNumeric concept idIndex codes; anatomic location cross-reference; FHIR category and conclusion codesYes, SNOMEDCT, crosswalk source SNOMEDCT_US
FMADistributed through BioPortalBare numberAnatomic location cross-reference; basis of the location type classificationYes, FMA
UMLSUS National Library of MedicineC plus seven digitsCrosswalk hub; anatomic location cross-referenceYes, through UMLS Terminology Services
MeSHUS National Library of MedicineTree numbers such as A07.231.114.145Anatomic location cross-reference onlyNo
LOINCRegenstrief InstituteDigits, hyphen, check digitExam type code on the Exam Finding List; a few index codesYes, LOINC, crosswalk source LNC
LOINC/RSNA Radiology PlaybookRegenstrief Institute and RSNA jointlyLOINC codes; legacy RPIDNamed in exam type goals onlyNot as a distinct source
RadElementACR and RSNARDES and RDE plus digitsIndex codes on CDE-derived finding models; CDE set and element identityNo
Radiology Gamuts OntologyPublished at gamuts.netGamut identifiers; GMTS as an OIDM organization codeIndex codes; source of the largest block of finding model contentNo
DICOM Controlled TerminologyNEMANumeric DCM codesSeries, instance, and SOP identity in raw FHIR input samplesNo
ICD-10-CM and ICD-10-PCSNational and international maintainersAlphanumericNamed in the lookup tool’s non-radiology profiles onlyNot in the default profile

RadLex

The radiology lexicon published by the RSNA, and the terminology OIDM leans on hardest. It supplies the primary key for anatomic locations in the form of a RadLex ID, and it is the second most common index code system in the finding model corpus, with 25,765 occurrences.1 Presence values across the corpus are coded with it, for example RID28472 for present and RID28473 for absent.

The ontology ships as an OWL file in the RSNA repository, which the next-generation vocabulary analysis identifies as the authoritative artifact going forward.23 That analysis also records the licence position: RadLex is “actively governed, and freely licensed for commercial and non-commercial use.”3 In OIDM data the system string is RADLEX; in FHIR encodings the system URI is http://www.radlex.org.4 Details of the relationship in both directions, including the open RSNA issue to fold the OIDM anatomic set into RadLex, are in RadLex integration.

SNOMED CT

The general clinical terminology, and by raw count the most used index code system in the finding model corpus at 27,773 occurrences.1 It is a secondary coding system rather than a key: findings, attributes, and attribute values carry SNOMED codes alongside RadLex ones, and the FHIR lineage samples use http://snomed.info/sct for a report’s category and conclusion codes.4

On anatomic locations SNOMED is a cross-reference. The curated 2022 dataset carries 1,732 SNOMED codes across 2,890 records; the current export carries a snomedId on 1,782 of 2,926 records.56

The system string is inconsistent in the corpus. SNOMED appears 27,773 times and SNOMEDCT 89 times for the same terminology.1 The lookup tooling uses SNOMEDCT as the BioPortal acronym and SNOMEDCT_US as the UMLS source abbreviation.7 SNOMED CT is licensed, which is why the tooling treats it as a credentialed backend and keeps “licensed SNOMED/UMLS behavior opt-in and visible.”8

FMA

The Foundational Model of Anatomy, a reference ontology of human anatomy distributed through BioPortal.9 In OIDM it is an anatomic cross-reference, present on 1,643 of the 2,890 records in the curated dataset and 1,649 of the 2,926 in the current export, in both cases the most common entry in the codes array.56 Its top-level organization also shapes the location type classification in the current package. Codes are carried as bare numbers with system: "FMA", for example 265256 for uterine adnexa.

UMLS

The National Library of Medicine’s integration of source vocabularies under shared concept unique identifiers.10 OIDM uses it for two jobs. It is the hub the lookup tool crosswalks through, resolving a concept to its CUIs and then translating to other vocabularies, with the default crosswalk targets set to SNOMEDCT_US, FMA, RADLEX, and LNC.7 And it is an anatomic cross-reference, on 578 of the 2,890 curated records and 580 of the 2,926 current ones.56

UMLS requires a licence and an API key from UMLS Terminology Services. The lookup roadmap is explicit that a CUI link is evidence rather than proof, and that translation should preserve “mapping direction, scope, provenance, and strength instead of treating every cross-reference as equivalence.”8

MeSH

Medical Subject Headings, also from the National Library of Medicine.11 MeSH has exactly one role in OIDM: an anatomic location cross-reference, the least common of the four, on 232 of the 2,890 curated records and 233 of the 2,926 current ones, carried as MeSH tree numbers such as A07.231.114.145 rather than descriptor identifiers.56 No OIDM tool resolves MeSH, and it is not among the terminologies the lookup library queries.

LOINC and the Radiology Playbook

LOINC is the Regenstrief Institute’s system for identifying laboratory and clinical observations, including imaging procedures.12 In OIDM its main job is exam type identification on the Exam Finding List exam header, covered in exam types.

LOINC also appears, sparingly, as an index code system: 23 occurrences across the whole finding model corpus, on two definitions.1 Those two are instructive about what LOINC is good for in this context. The Glasgow Coma Scale model codes its attributes with LOINC observation codes such as 9267-6 for eye opening, and its values with LOINC answer-list codes such as LA6553-7 for no eye opening. The CDE set schema likewise admits LOINC as one of three permitted index code systems.13

The Radiology Playbook is the radiology portion, governed jointly by the Regenstrief Institute and the RSNA, shipping twice yearly, freely licensed, and a separate artifact from RadLex.314 Nothing in OIDM consumes it today. Its legacy RPID identifiers were folded into LOINC, so new procedure codes take LOINC form.8

RadElement

The ACR and RSNA registry that publishes CDE sets and CDE elements.15 It is both a publication venue and a coding system. RADELEMENT appears 115 times as an index code system in the finding model corpus, exactly on the CDE-derived definitions.1 In FHIR encodings the lineage uses https://radelement.org as the coding system with an RDES or RDE code.

RadElement is the one terminology in this table that OIDM both consumes and feeds. No OIDM lookup tool resolves it, and there is no settled coding-system URI for its codes; both points are covered in CDEs and RadElement.

Radiology Gamuts Ontology

An ontology of radiologic differential diagnosis lists, published at gamuts.net.16 It plays two roles at once. As a coding system, GAMUTS appears 1,935 times in the corpus, essentially once per Gamuts-derived definition.1 As a contributing organization it holds the organization code GMTS, which is the middle segment of 1,933 of the 2,382 finding model identifiers. See content catalog for what that content is and finding model content direction for where it is headed.

DICOM Controlled Terminology

The DCM code set from the DICOM standard, with the system URI http://dicom.nema.org/resources/ontology/DCM.17 It appears in OIDM only in the raw FHIR reports used as extraction input, where it labels imaging identity components such as 113607 Series Number and 113609 Instance Number.4 It is not used anywhere in the OIDM data structures themselves. Two other vocabularies appear in those same input samples and nowhere else: HL7 terminology code systems for report category and identifier type, and UCUM for units.

ICD

ICD does not appear in any OIDM data structure or definition. It is named once, in the lookup tool’s profile design, which places ICD-10-CM and ICD-10-PCS in clinical and billing-us profiles, notes they are available through BioPortal and UMLS “under the UMLS license,” and keeps them deliberately out of the radiology default.8 It is listed here so that a reader who expects diagnosis coding to be part of OIDM can see that it is not.

Footnotes

  1. The 2,382 finding model definitions, findingmodels main branch ↩ ↩2 ↩3 ↩4 ↩5 ↩6

  2. RadLex OWL file, RSNA RadLex repository ↩

  3. Current understanding, ACR-RSNA-CDEs next-gen-2026 ↩ ↩2 ↩3

  4. Raw FHIR DiagnosticReport input sample ↩ ↩2 ↩3

  5. Curated anatomic location dataset, version 1.0.0-rc.1 ↩ ↩2 ↩3 ↩4

  6. Current anatomic location export, findingmodel main branch ↩ ↩2 ↩3 ↩4

  7. Default ontologies and source abbreviation maps, med-ontology-lookup ↩ ↩2

  8. med-ontology-lookup product roadmap ↩ ↩2 ↩3 ↩4

  9. Foundational Model of Anatomy on BioPortal ↩

  10. Unified Medical Language System ↩

  11. Medical Subject Headings ↩

  12. LOINC, Regenstrief Institute ↩

  13. Differences between the CDE set schema and the RadElement API ↩

  14. LOINC/RSNA Radiology Playbook ↩

  15. RadElement registry ↩

  16. Radiology Gamuts Ontology ↩

  17. DICOM Controlled Terminology, DCM code set ↩

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