8 FHIR: ConceptMap

Concept map tutorial: https://fhir-drills.github.io/conceptmap.html

A ConceptMap defines a mapping from a set of concepts defined in a code system to one or more concepts defined in other code systems. In radiology data science, this resource is essential for translating between different terminology systems and ensuring semantic interoperability.

8.1 Definition and Purpose

A statement of relationships from one set of concepts to one or more other concepts - either concepts in code systems, or data element/data element concepts, or classes in class models.

Key Characteristics: - Mappings are one way - from the source to the target system - Mappings between code system concepts are only intended to be defined in the context of a particular business usage - Each mapping from a source concept to a target concept includes a relationship element describing the semantic correspondence between the two

8.2 Core Structure

The ConceptMap has several key components:

8.2.1 1. Metadata Elements

url: Canonical identifier
version: Business version
name: Computer-friendly name
title: Human-friendly name
status: Publication status (draft | active | retired | unknown)
description: Natural language description

8.2.2 2. Scope Definition

sourceScope[x]: The source value set containing concepts to be mapped
targetScope[x]: The target value set providing context for mappings

8.2.3 3. Group Structure

group: Groups mappings by source and target systems
source: Source system (CodeSystem)
target: Target system (CodeSystem)

8.2.4 4. Element Mappings

element: Individual concept mappings
code: Source concept code
target: Target concept(s) with relationships

8.3 Radiology-Specific Examples

8.3.1 Example 1: DICOM Modality to SNOMED CT Mapping

{
  "resourceType": "ConceptMap",
  "id": "dicom-modality-to-snomed",
  "url": "http://radiology.hospital.com/fhir/ConceptMap/dicom-modality-to-snomed",
  "version": "1.0.0",
  "name": "DicomModalityToSnomedCT",
  "title": "DICOM Modality to SNOMED CT Mapping",
  "status": "active",
  "description": "Mapping between DICOM modality codes and SNOMED CT procedure concepts",
  
  "sourceScopeCanonical": "http://dicom.nema.org/medical/dicom/current/output/chtml/part16/sect_CID_29.html",
  "targetScopeCanonical": "http://snomed.info/sct",
  
  "group": [{
    "source": "http://dicom.nema.org/resources/ontology/DCM",
    "target": "http://snomed.info/sct",
    "element": [
      {
        "code": "CT",
        "display": "Computed Tomography",
        "target": [{
          "code": "77477000",
          "display": "Computerized axial tomography",
          "relationship": "equivalent"
        }]
      },
      {
        "code": "MR",
        "display": "Magnetic Resonance",
        "target": [{
          "code": "113091000",
          "display": "Magnetic resonance imaging",
          "relationship": "equivalent"
        }]
      },
      {
        "code": "US",
        "display": "Ultrasound",
        "target": [{
          "code": "16310003",
          "display": "Diagnostic ultrasonography",
          "relationship": "equivalent"
        }]
      }
    ]
  }]
}

8.3.2 Example 2: RadLex to ICD-10 Body Part Mapping

{
  "resourceType": "ConceptMap",
  "id": "radlex-to-icd10-bodypart",
  "url": "http://radiology.hospital.com/fhir/ConceptMap/radlex-to-icd10-bodypart",
  "version": "2.0.0",
  "name": "RadLexToICD10BodyPart",
  "title": "RadLex Anatomy to ICD-10 Body Part Mapping",
  "status": "active",
  "description": "Mapping RadLex anatomical terms to ICD-10 body part codes for billing purposes",
  
  "useContext": [{
    "code": {
      "system": "http://terminology.hl7.org/CodeSystem/usage-context-type",
      "code": "workflow"
    },
    "valueCodeableConcept": {
      "coding": [{
        "system": "http://terminology.hl7.org/CodeSystem/v3-ActCode",
        "code": "BILLING",
        "display": "Billing"
      }]
    }
  }],
  
  "sourceScopeCanonical": "http://radlex.org",
  "targetScopeCanonical": "http://hl7.org/fhir/sid/icd-10",
  
  "group": [{
    "source": "http://radlex.org",
    "target": "http://hl7.org/fhir/sid/icd-10",
    "element": [
      {
        "code": "RID1301",
        "display": "lung",
        "target": [{
          "code": "J98.4",
          "display": "Other disorders of lung",
          "relationship": "source-is-narrower-than-target",
          "comment": "RadLex lung maps to broader ICD-10 category for billing"
        }]
      },
      {
        "code": "RID1240",
        "display": "heart",
        "target": [{
          "code": "I25.9",
          "display": "Chronic ischemic heart disease, unspecified",
          "relationship": "source-is-narrower-than-target"
        }]
      }
    ]
  }]
}

8.3.3 Example 3: LOINC to Local Lab Code Mapping with Dependencies

{
  "resourceType": "ConceptMap",
  "id": "loinc-to-local-imaging",
  "url": "http://radiology.hospital.com/fhir/ConceptMap/loinc-to-local-imaging",
  "version": "1.2.0",
  "name": "LoincToLocalImagingProcedures",
  "title": "LOINC to Local Imaging Procedure Mapping",
  "status": "active",
  "description": "Maps LOINC imaging procedure codes to local hospital procedure codes",
  
  "additionalAttribute": [{
    "code": "contrast-agent",
    "description": "Whether contrast agent is used",
    "type": "boolean"
  }],
  
  "sourceScopeCanonical": "http://loinc.org",
  "targetScopeCanonical": "http://hospital.local/procedures",
  
  "group": [{
    "source": "http://loinc.org",
    "target": "http://hospital.local/procedures",
    "element": [
      {
        "code": "36643-5",
        "display": "CT chest",
        "target": [
          {
            "code": "CT-CHEST-001",
            "display": "CT Chest without contrast",
            "relationship": "equivalent",
            "dependsOn": [{
              "attribute": "contrast-agent",
              "valueBoolean": false
            }]
          },
          {
            "code": "CT-CHEST-002",
            "display": "CT Chest with contrast",
            "relationship": "equivalent",
            "dependsOn": [{
              "attribute": "contrast-agent",
              "valueBoolean": true
            }]
          }
        ]
      }
    ]
  }]
}

8.4 Relationship Types

The relationship element describes the semantic correspondence between source and target concepts:

equivalent: Concepts are exactly the same
source-is-narrower-than-target: Source concept is more specific
source-is-broader-than-target: Source concept is more general
related-to: Concepts are related but not equivalent
not-related-to: No valid mapping exists

8.5 The $translate Operation

A key concept for the ConceptMap resource is the $translate operation. This operation is a formal definition of an API by which a terminology server can allow clients to ask for a translation to be done based on the content in the ConceptMap resource.

8.5.1 **Example $t r a n s l a t e R e q u e s t : * * ‘ ‘ ‘ h t t p P O S T [b a s e] / C o n c e p t M a p /$ translate

Content-Type: application/fhir+json

{ “resourceType”: “Parameters”, “parameter”: [ { “name”: “url”, “valueUri”: “http://radiology.hospital.com/fhir/ConceptMap/dicom-modality-to-snomed” }, { “name”: “system”, “valueUri”: “http://dicom.nema.org/resources/ontology/DCM” }, { “name”: “code”, “valueCode”: “CT” } ] } ```

8.6 Radiology Data Science Applications

1. Terminology Harmonization**: Convert between DICOM, SNOMED CT, RadLex, and LOINC codes for consistent data analysis.

2. Multi-institutional Studies**: Map local procedure codes to standardized terminologies for collaborative research.

3. AI Model Training**: Ensure consistent labeling across different datasets using standardized mappings.

4. Clinical Decision Support**: Translate imaging findings to standardized terminologies for rule-based systems.

5. Billing Integration**: Map clinical terminologies to billing codes (ICD-10, CPT) for revenue cycle management.

The ConceptMap resource enables semantic interoperability across radiology systems, supporting data integration, analytics, and standardized reporting essential for modern radiology data science workflows.