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.

Foreign Exam Management use cases cover three main areas requiring standardization:

• Document and Image Sharing
• Imaging Report Format
• Anatomic Region Code

Listed below are the available standards considered for each standardization category, the chosen alternative being highlighted.

Standard	Fit for Purpose			Stewardship		Quality
	Fits Requirements	Implementation Type	Vendor Support	Canadian Steward	SDO Maintained	Complexity	Standard Maturity	Training, Support and Tooling
IHE Cross-Enterprise Document Sharing - Imaging (XDS/XDS-I)		Production in Canada		Yes	Yes		High
DICOM / HL7 v2 and Clinical Document Architecture (CDA)		Production in Canada		No	Yes		High
Architectural Constraints and Considerations				Secondary Benefits
None of these standards impose significant architectural constraints
Recommendation				Supporting Rationale
IHE Cross-Enterprise Document Sharing - Imaging (XDS/XDS-I)				The IHE XDS-I.b profile specifies the use of existing standards including HL7 v2/CDA 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.

Note:

The IHE XDS/XDS-I profile builds upon the foundational HL7 and DICOM standards by identifying the roles of different actors participating in the information exchange and specifying how data exchange transactions and applicable standards enable document sharing.  It also prescribes an affinity domain process that was employed by the Canadian Diagnostic Imaging Community to constrain areas of optionality in the IHE XDS/XDS-I profile to Canadian requirements.  The XDS Affinity Domain Implementation Guide is the work product of this group.

Report Format

XDS/XDS-I supports a range of report formats through the use of different transaction and reporting

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.

Note:

Anatomic Region was localized for Canadian use.