Introduction
- Technical standards adoption. While there are open technical solutions for image exchange, such as Integrating the Healthcare Enterprise (IHE) Cross-Enterprise Document Sharing for Imaging (XDS-I) [5], that have gained adoption in some countries, they have not gained widespread adoption in other markets (e.g., the US market). Many of the solutions in the USA are still proprietary.
- Image type standardization [6]. Though one might immediately think of the Digital Imaging and Communications in Medicine (DICOM) [7] standard when discussing medical imaging, providers also need solutions that address images and related content in other formats, such as a JPEG image of a wound captured with a digital camera or a PDF of an EKG tracing. Two approaches have been considered, though most practical experience focuses on the first:
- DICOM
- DICOM-wrapping of non-native DICOM object types (e.g., JPEG, MPEG, and PDF)
- Mixed file formats, including DICOM, JPEG, MPEG, and PDF.
- Exchanging in the original binary file format, both DICOM and others
- Governance [8]. Successful image exchange requires more than just technology—a trust framework is needed to address several key considerations, including:
- Which organizations will participate, and for what use cases?
- Which individuals have access to look at images? How is that access managed?
- What is the breadth of participants? (State? National? International?)
- What is the remediation path to address concerns that may arise?
- How will participants identify patients within the exchange network?
- Business incentive. Implementation of an image exchange requires a business case to justify the cost and responsibilities it implies. In the USA, the traditional fee-for-service model is gradually shifting towards a performance-based system that incentivizes outcomes and reduced cost. Novel programs, such as Accountable Care Organizations (ACOs) [9], will benefit from image exchange by reducing the cost of unnecessary duplicative testing.
- Security and Privacy. Increased flow of patient data between organizations must be balanced with the necessity of keeping that data safe and secure. While not discussed in this paper, secure exchange and privacy must be considered in an image exchange solution.
Three Standards-Based Image Exchange Implementations
Implementation #1: Ontario, Canada
Background and Requirements
Item | Diagnostic image repository #1 (DIR1) (uses DICOM query/retrieve) East Toronto | Diagnostic image repository #2 (DIR2) (uses XDS-I) West Toronto |
---|---|---|
Patient identification | Deterministic match based on provincial Ontario Health Card Number. | PIX lookup: probabilistic patient matching based on a scorecard of key demographics. |
Image discovery | DICOM (C-Find, C-Move, etc.) | XDS registry query |
Report retrieval | Report txt is available from a well formed URL. Edge device will scrape contents of URL and convert to ORU. | Reports stored in document repository in CDA format. Edge device will convert CDA to ORU or DICOM Secondary capture depending on site’s preference. |
Number of contributing sites | 98 | 29 |
Patient population | ≈ 4.2 Million patients | ≈ 4 Million patients |
Number of unique PACS vendors connected | 9 | 9 |
Annual exam | ≈ 5 Million exams annually | ≈ 3 Million exams annually |
DIR1—East Toronto
DIR2—West Toronto
- A score greater 70 is considered a positive patient match.
- A score less than 63 is considered a different patient record.
- A score 63–70 is considered an uncertain link and requires human intervention to review and manually match or break the “uncertain link.”
- Physician reliance on access to outside images and reports for patient care
- Reduction in CD imports
- Reduction in repeat imaging for patients
Implementation #2: ELGA in Austria
Background, Approach, and Architecture
Challenges and Learnings
- When should the images be registered (DICOM KOS for the imaging manifest created) resulting in an update in the XDS registry?
- What to do if a series that has already been registered is updated?
- Should a new KOS be created/registered or should the old one be updated?
- How to integrate the APPC (Austrian PACS Procedure Codes) in the KOS?
- How to deal with thumbnails?
- How to deal with the fact, that the patient portal in ELGA (which is delivered from another vendor) does not support images at the moment?
- How patients can withdraw their consent. ELGA has an opt-out system, rather than opt-in. This means that every patient automatically participates in ELGA—patients must explicitly withdraw their consent if they wish to opt-out
Opportunities
- Provides a mechanism to query/retrieve DICOM imaging objects using DICOM RESTful web services enabling ease of image access on non-traditional DICOM devices (e.g., mobile devices)
- Can leverage and utilize the existing XDS-I infrastructure
- Can access related imaging documents by integrating with IHE MHD (mobile access to health documents)
- Easy to work across firewalls using HTTP(S) compared to traditional DICOM (DIMSE)
- Easy to support authentication and encryption using HTTPS compared to DICOM
- Not dependent on a secure network (VPN) between endpoints
Implementation #3: USA—RSNA Image Share Network
Approach
Outcomes
Expanding RSNA Image Share to Support Image Exchange for Research Using Emerging Standards
Conclusion and Recommended Advocacy
- Providing a single shared trust framework for all participants that mandates and protects availability of the data and access to it—so that individual legal agreements do not need to be negotiated between each pair of exchange partners.
- Defining what data is to be exchanged and in what standard formats it will be encoded.
- Defining the breadth of participants (international/national/regional/state/organizational/individual)
- Specifying how access is managed, secured, and audited.
- Creating a national or regional patient identifier, or standing up a patient identifier cross-referencing service, to aid in discovering, associating, and accessing the right images for the right patient.