Purpose
This guide provides an overview of available standards and a recommended approach to support the Foreign Exam Management requirements as identified below. The intent is to simplify standards selection decisions in future projects and, in turn, to promote standardization of solutions across projects by providing useful information to support decision making in a readily consumable format.
Content in this guide was summarized from the Canadian XDS Affinity Domain Implementation Guide v1.1 20140527 to provide an accessible overview of the standards selected to support the listed Use Cases.
Business Context
Foreign Exam Management (FEM) relates to those scenarios where a health care provider organization with local Radiology Information System (RIS) and Picture Archiving and Communication System (PACS) needs to allow users to retrieve and view an “imaging exam that was ordered, acquired, and reported on at some site external to the one where the study is currently being imported.” (IHE Import Reconciliation Workflow Supplement for Trial Implementation)
Although existing systems provide the means to import Foreign Exams from external sources manually, the integration of local systems with shared Diagnostic Imaging Repositories (DI-R) introduces new workflows and requirements in need of standardization, including:
- Automated import (fetching) of prior exams, and
- Rules for local management of content which is maintained within and readily available from alternate source systems.
Covered Use Cases
The following requirements help frame the need for standardization to support Foreign Exam Management. They assume integration between local RIS / PACS and a shared DI-R already exists.
UC-1 Workflow
The focus of FEM use cases is acquisition (“fetching”) of relevant foreign exams for display and use by health care providers during the course of a current patient encounter. Image sets can be very large and therefore the ability to “pre-fetch” images before they are required for viewing is desired to improve user productivity.
The XDS Affinity Domain Implementation Guide identifies a number of use cases which are summarized here:
UC-1.1 Pre-Fetching
- Patient related events at the local facility trigger an automatic search for relevant prior exams on the DI-R:
- Basic example: request related prior images when an exam is ordered, initiate query on patient arrival to radiology,
- Non-radiology example: patient arrival at clinic (e.g. oncology, neurology) triggers search for relevant exams, or
- Report only example: similar to examples above but return reports only.
- Relevant image sets and reports are automatically retrieved and brought in to the local hospital system for review.
- Information retrieved should not be archived locally as it remains available from the DI-R.
UC-1.2 Ad-Hoc or On-Demand Image Fetch
- A user at the local facility manually initiates a query to find existing relevant prior images for a specified patient and selects image sets of interest from a list of results.
- Relevant image sets and reports are retrieved and brought in to the local hospital system for review.
- Information retrieved should not be archived locally as it remains available from the DI-R.
UC-1.3 Amendments
- Identifies steps to replace foreign report when a report is amended after pre-fetch.
- Identifies steps to replace an image set when an image is added or changed after pre-fetch.
UC-1.4 Emergency Patients
- Identifies options to use DI-R / FEM to improve workflow when patient arrives at hospital via ambulance.
UC-2 Identification of Relevant Prior Exams
Fetching or pre-fetching of relevant information requires consistent use of metadata to determine relevance.
- Identifiers used to specify the acquisition modality and anatomic region of the study need to be standardized.
UC-3 Retention of Foreign Information
Foreign content should be identifiable within local systems and should not be archived or retained long term.
Evaluated Standards & Recommended Approach
The following standards and related specifications were identified as candidates to support the in-scope requirements. Recommended standards are identified with summary of the rationale.
Areas of Standardization
Standardization Requirement | Options | Choice | Rationale |
Document and Image Sharing | IHE Cross-Enterprise Document Sharing - Imaging (XDS/XDS-I) | X | The IHE XDS-I.b profile specifies the use of existing standards including HL7 and DICOM to enable registration and sharing of images and reports. A Canadian XDS Affinity domain guide is available to support implementation of the profile. |
DICOM / HL7 |
| ||
TBD |
|
|
|
Report Format | Clinical Document Architecture (CDA) R2 | X | It is the goal of the Canadian XDS Affinity domain that reports will be stored in HL7 CDA format (using the pan-Canadian header format) as these reports (a) support required metadata, and (b) can be transformed to all other formats.
* Raw text based HL7 ORU and DICOM SR are widely used and present in DI-R systems. |
Portable Document Format (PDF) |
| ||
DICOM SR / SC | * | ||
Raw Text | * | ||
Anatomic Region Code | Coarse Body Parts (SNOMED CT subset) | X | The DICOM CID 4 value set is very detailed and generally inconsistent with the general approach of “casting a wide net” employed when fetching content within the FEM use cases. |
Anatomic Region (DICOM CID 4) |
|
Document and Image Sharing
Foreign Exam Management will be implemented by an organization participating a jurisdictions’ shared Diagnostic Imaging Repository (DI-R) system. The DI-R will provide for registration and long term storage of sets of images and reports and standards based services that will be leveraged and, possibly, upgraded to support the FEM use case(s).
Standard | Maturity | Sustainability | Implementation | ||||
Standards Process | Implementation | Canadian Implementation | Superseded? | Vendor Support | Complexity | Training, Support and Tooling Availability | |
IHE Cross-Enterprise Document Sharing - Imaging (XDS/XDS-I) | Final | Production | Production | No | High | High | Good |
DICOM / HL7 | Final | Production | Production | No | High | High | Good |
Architectural Constraints and Considerations | Secondary Benefits | ||||||
None of these standards impose significant architectural constraints |
| ||||||
Recommendation | Supporting Rationale | ||||||
HE Cross-Enterprise Document Sharing - Imaging (XDS/XDS-I) | The IHE XDS-I.b profile specifies the use of existing standards including HL7 and DICOM to enable registration and sharing of images and reports. A Canadian XDS Affinity domain guide is available to support implementation of the profile. |
Report Format
XDS/XDS-I supports a range of report formats through the use of different transaction and reporting
Standard | Maturity | Sustainability | Implementation | ||||
Standards Process | Implementation | Canadian Implementation | Superseded? | Vendor Support? | Complexity | Training, Support and Tooling Availability | |
Clinical Document Architecture (CDA) R2 | Final | Production | Production | No | High | High | Good |
Portable Document Format (PDF) | Final | Production | Production | No | High | Medium | Good |
DICOM SR / SC | Final | Production | Unknown | No | High | ? | Good |
Raw Text | Final | Production | Unknown | No | High | Low | Good |
Architectural Constraints and Considerations | Secondary Benefits | ||||||
None of these standards impose significant architectural constraints | PDF may preclude secondary use, while the structured data of a CDA document supports machine readability and may enable secondary use of clinical data, clinical decision support or application of administrative/demographic data to analytics/business intelligence | ||||||
Recommendation | Supporting Rationale | ||||||
Clinical Document Architecture (CDA) R2 | It is the goal of the Canadian XDS Affinity domain that reports will be stored in HL7 CDA format (using the pan-Canadian header format) as these reports (a) support required metadata, and (b) can be transformed to all other formats. |
Anatomic Region Code
Metadata plays an important role in the identification of relevant priors during the fetch and pre-fetch use cases. The significant coded metadata elements for the FEM use case are the acquisition modality of image and the anatomical region being studied. Acquisition modality was adopted as prescribed. This section identifies options considered to identify the Anatomic Region.
Standard | Maturity | Sustainability | Implementation | ||||
Standards Process | Implementation | Canadian Implementation | Superseded? | Vendor Support? | Complexity | Training, Support and Tooling Availability | |
Coarse Body Parts (SNOMED CT subset) | Final | Production | Production | No | High | High | Good |
Anatomic Region (DICOM CID 4) | Final | Production | Production | No | High | Medium | Good |
Architectural Constraints and Considerations | Secondary Benefits | ||||||
None of these standards impose significant architectural constraints | Use of SNOMED CT to encode the Canadian code set may help enable mapping from the DI Procedure Codes to the Coarse Body parts and/or definition of automated validation. | ||||||
Recommendation | Supporting Rationale | ||||||
Clinical Document Architecture (CDA) R2 | The DICOM CID 4 value set is very detailed and generally inconsistent with the general approach of “casting a wide net” employed when fetching content within the FEM use cases. |
Implementation Resources
Existing Implementations