Import and Display of External Priors- Proposal

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1. Proposed Workitem: Import and Display of External Priors (IDEP)

  • Proposal Editor: Teri Sippel Schmidt
  • Proposal Contributors: David Koff MD; Canada Health Infoway; Kevin O'Donnell
  • Editor: Jonathan Whitby (previously Teri Sippel Schmidt)
  • Contributors: David Koff MD; Canada Health Infoway; Teri Sippel Schmidt
  • Domain: Radiology

This proposal was previously called "Foreign Exam Management (FEM)".

2. The Problem

Prior imaging studies provide vital information and context to the radiologist when interpreting a current study, even resulting in a change of diagnosis. A "prefetch" step (to locate prior studies for the patient that may be relevant and make them immediately accessible to the radiologist during review) is common in imaging workflows. This works fairly well for priors that were performed locally, even if they have to be pulled back from longer term storage to be ready for the radiologist.

Unfortunately, with the mobility of modern healthcare, it is very common for priors to be located outside the reading institution.

Although there have been many improvements to the ability to exchange images between enterprises, or between departments within an enterprise, the ability to locate, access, and view priors for direct comparison, particularly during the short time frame required for them to be relevant to reading, is still not reliable.

  • patient portals - are unwieldy, slow to access, and on different monitors
  • web-based viewers - are not integrated into the diagnostic workstation so they don't permit side-by side image comparison and use of local hanging protocols or viewing tools
  • CD/DVD imports/viewers - are often not timely, sometimes do not import reliably, and are "reactive not proactive"
  • all suffer from issues with different Patient IDs, procedure codes, etc, questions of long term storage, and some mappings not addressed in IRWF.b.
  • radiology reports - there is no primary standard for radiology reports, and as a result, report formats vary dramatically effectively eliminating interoperability of report sharing


A solution for this priors problem has been demonstrated to also reduce re-scanned patients (with cost and radiation implications) due to poor access to studies performed at other institutions. (Ref: Nagels, J., Macdonald, D. & Coz, C. J Digit Imaging (2017). https://doi.org/10.1007/s10278-017-9963-8)

3. Key Use Case

Use Case 1: Reviewing current imaging study along with external priors

This scenario is widely supported when restricted to locally-acquired imaging studies. The goal of this supplement is to ensure that it is consistently supported between institutions and to work in conjunction with the existing install base of PACS systems without necessitating changes or upgrades.

The burden is centralized in the Importer and Report Converter actors rather than distributed to every sending or receiving system.


User Scenario

  • A physician orders a radiology study for a patient
  • The radiologist wants to review the new study along with any relevant priors (MaxUE: and their associated reports)
  • Acquired locally
  • Acquired at affiliated institutions
  • The radiologist wants all prior studies (MaxUE: and reports) to work correctly with all their normal reading tools
  • Consistent patient identifiers
  • Consistent procedure codes
  • Consistent body parts
  • Etc.
  • The import system finds, localizes and imports all relevant prior imaging studies (MaxUE: and reports)
  • The radiologist reads the study, accessing all priors using their usual workflow, display, hanging protocols, and image tools


Supporting Data Flow

  • The import system receives the radiology order and extracts key metadata
  • Patient identifiers
  • Procedure codes
  • Modality
  • The import system queries the EMPI to determine appropriate patient identifiers for each affiliated site
  • The import system searches each affiliated site for prior imaging studies for the patient, retrieving key metadata for each study
  • Modality
  • Procedure codes
  • Study dates
  • MaxUE: The import system searches each affiliated site for diagnostic imaging reports for the patient, retrieving key metadata for each report
  • Report domain (if repository not radiology-specific)
  • Report codes
  • Report dates
  • The import system filters prior imaging studies based on order metadata, query results and configured relevancy rules
  • MaxUE: The import system filters prior diagnostic imaging reports based on order metadata, query results and configured relevancy rules
  • The Importer retrieves prior imaging studies that match the filter
  • MaxUE: The Importer retrieves prior diagnostic imaging reports that match the filter
  • The import system executes import logic to localize import imaging studies (MaxUE: and diagnostic imaging reports)
  • Replacing existing patient identifiers and demographics with local values
  • Etc.
  • The import system stores the imported imaging studies to the local PACS
  • MaxUE: The import system stores the imported diagnostic imaging reports to the local report repository
  • After radiological interpretation of the current study, external data is purged according to local policies
  • Triggers on current study report being finalized


Human Version of the Clinical Use Case

Dr. Smith, a radiologist at a busy Cancer Center, is reporting a large number of CT studies which require comparison to previous imaging often performed at remote (but secure network connected) sites in the region, mostly community hospitals, but also academic centres where the patient may have been seen. The radiologist has to evaluate changes over time in order to assess treatment efficiency, with previous performed usually 3 to 6 months earlier. There may be a series of previous studies at the same interval over a period of a few years.

Dr. Smith needs to report on a lesion’s change in size and appearance, as well as interval development or resolution of other conditions such as metastatic disease, peritoneal seeding or pleural effusions. For accuracy and speed, Dr Smith has to be able to cross-reference his CT slices and MPRs in DICOM format, using his own measurement tools.

Dr. Smth wants the remote CT(s) to be readily available in his patient folder on his own PACS, and the studies displayed using his hanging protocols. He wants the report to be available the same way he displays previous reports for studies performed in his institution.


The Problem Case Today

Dr. Smith has to access a separate website, maybe with a separate sign-on. He has to search a separate database, he has to wait for images to load, slowing him down through his very busy work day. To make things worse, Dr. Smith has to open two separate web interfaces, one for the images, another one for the report, as the VNA was not be able to move the report with the images.

Even though studies are all stored on a central VNA or there is access to other DICOM PACS systems, Dr. Smith has to ask the remote site to print a CD/DVD with the images. He then asks his PACS team to upload these images into his local PACS to make sure that images are available when he reports the current study. Not only is this a tedious manual process, but it delays the time the study is reported sometimes up to a few days. And, using the CD/DVD method, it is common that the previous report is not available.


Workflow steps to be addressed

  • patient identification and PID reconciliation
  • receipt of new orders
  • metadata that can be applied to the relevancy logic
  • imaging study retrieval
  • DICOM attribute mapping / localization
  • storage of imported imaging studies
  • MaxUE: diagnostic imaging report retrieval
  • MaxUE: HL7 v2 ORU diagnostic imaging report attribute mapping
  • MaxUE: storage of imported diagnostic imaging reports
  • local purging of foreign imaging studies and foreign diagnostic imaging reports as defined Option

This is intended to be a Workflow profile with one primary use case and one of two back-end architectures (all-DICOM and XDS.b (XDS.b as named option)).


Assumptions

Goal is to enable automated and contextually integrated VIEWING of foreign radiology priors at the local system.

  • Focus is on simplicity and existing installed base ("old school") - DICOM, HL7 v2.x, and XDS
  • not image access using DICOM web services, or storage of reports using FHIR, etc.
  • Secure network already in place between facilities
  • Cross- non-affiliated enterprises out of scope
  • EMPI (PIX/PDQ) already in place between facilities
  • Access prior imaging studies using DIMSE DICOM, but have XDS-I as a named Option
  • XDS-I Pption would include hybrid DICOM/XDS.b environment
  • Storage of imaging study limited to DIMSE DICOM to the local PACS
  • i.e. no direct XDS import to the local PACS
  • Other image types such as Raw JPEG, PDF, etc. out of scope
  • MaxUE: Report formats are limited to TEXT and PDF
  • MaxUE: Access of prior reports is limited to FHIR query for reports
  • MaxUE: Storage of prior reports is limited to HL7 v2.5.1 ORU with TEXT or PDF content
  • MaxUE: Report semantic content is always out of scope, i.e., structured or unstructured, etc.
  • This could cause non-interoperability (unable to view), but is still out of scope and must be managed locally

4. Standards and Systems

Real World Systems

  • EMPI (IHE: PIX/PDQ Manager)
  • RIS/EMRs (IHE: SWF.b DSS/OF, Report Manager, Report Reader)
  • VNA, Enterprise Imaging Repository or Diagnostic Imaging Repository (DI-r) (IHE: Image Manager, Report Manager, XDS.b Document Registry, XDS.b Document Repository, XDS.b Imaging Document Source, possibly Importer and/or Report Converter)
  • PACS (IHE: Image Manager/Archive, Image Display, Report Manager, Report Reader, possibly Importer and/or Report Converter)
  • Note: the Importer and Report Converter actors may be separate systems, combined with a system above, or combined together - See Deployment options in Volume 1


Standards

  • IRWF.b - useful importation logic and data mappings (but that IRWF.b is passive and doesn't specify pre and post steps)
  • PIX/PDQ - patient identification
  • MIMA Vol 2 Appendix J - fully qualified Patient ID reconciliation
  • HL7 v2.x ORM/OMI (RAD-4 + IRWF.b data mappings ) - access to orders for new studies at the local site
  • DICOM Q/R and XDS.b-I (RAD-5 and ITI-18) - find images
  • DICOM C-Move and XDS.b-I (RAD-5 and ITI-18) - retrieve images
  • DICOM C-Store - store images locally (default)
  • MaxUE: Mobile Health Documents (MHD) -FHIR query documents
  • MaxUE: XDS.b retrieve - report retrieval
  • MaxUE: HL7 v2.x ORU (RD:RAD-128) - store report locally as TEXT or PDF

Recommend limiting the required transactions on primary installed base (ie., HL7 v2.x, DICOM, XDS.b).

  • A Cross Profile Consideration should discuss how DICOMweb services could be integrated in the future for image access and retrieval.

5. Technical Approach

  • Assign most "intelligence" and mapping to new IDEP actors (Importer and Report Converter). This limits changes to ancillary systems.
  • Require certain specific data elements be populated, but avoid defining specific terminology mappings.
  • No intention to map procedure codes, study description, etc. Discuss in X.4 Concepts sections.
  • Communicate metadata to be able to determine relevancy, but do not define relevancy rules. Server side v. client side filtering. (although IDEP would specify client side filtering.)
  • Do not over-specify display requirements; e.g., "Shall indicate on the display that it is an external study."
  • Retain WIA for remote image access via web services in Cross Profile Considerations (X.6); but do not make it a requirement.


Existing actors

  • "Local" DSS/OF
  • "Local" Image Manager
  • "Remote" Image Manager
  • MaxUE: "Local" Report Manager
  • MaxUE: "Remote" Report Manager
  • PIX/PDQ Manager
  • XDS.b Registry
  • XDS.b Repository
  • XDS.b-I Imaging Document Source


New actors

  • Importer (same actor as IRWF.b, but additional behaviors)
  • MaxUE: Report Converter


Existing transactions

  • HL7 v2, DICOM DIMSE, XDS.b and FHIR transactions (i.e. focus on improving the functionality of the existing installed base)
  • See IDEP transaction diagram


New transactions (standards used)

  • "Query for Patient Studies": new DICOM query
  • New mapping tables
  • Order (OMI) message data for relevancy
  • Coercion of MHD data for External Prior Reports
  • HL7 v2 ORU for External Prior Reports Mapping

Impact on existing integration profiles

  • IOCM is "out of sync" with IDEP in terms of versions of standards used
  • IRWF.b and IDEP have overlap, but are not inconsistent and can peacefully co-exist for now.
  • IDEP is consistent with current SWF.b profile
  • SWF.b not being integrated into main standard makes it hard to put all of the pieces together.


New integration profiles needed

  • IDEP


Breakdown of tasks

Significant work has already been completed:

Transactions

  • Query for Patient Studies - get study metadata from local/remote PACS using pre-mapped Patient ID
  • returned information needs to be adequate for relevancy filtering
  • draft transaction exists based on C-FIND; cloned Query Images?
  • SP 1 effort
  • Review appropriateness of existing transactions
  • SP 1 effort (mostly work for editor)

Profile

  • Profile body - draft exists (68 pages); much is committee reviewed; not public commented
  • SP 2 effort
  • Use Case: IDEP with DIMSE Q/R mechanisms (baseline)
  • 14 existing transactions, 1 new transaction
  • confirm no gaps that would require change to any of the 14 existing
  • draft exists; much is committee reviewed; not public commented
  • SP 1 effort
  • SP 1 complexity
  • Use Case: IDEP with XDS-I Q/R mechanisms (option)
  • ~15 existing transactions, no new transaction?
  • draft exists; much is committee reviewed; not public commented
  • SP 1 effort
  • SP 1 complexity
  • Use Case: IDEP with Reports (option) (MaxUE)
  • adds ~6 transactions for finding/transporting Text/PDF reports using DIMSE, HL7v2 & MHD mechanisms
  • SP 1 effort
  • SP 1 complexity
  • Add new report transcoding specification for different wrappers and metadata mapping
  • SP 1 effort
  • SP 1 complexity
  • Remove all references to reports & Report Converter (40% of document) - If MinUE
  • SP 0 effort (work on editor)
  • Confirm different deployment models
  • draft exists; much is committee reviewed; not public commented
  • SP 1 effort
  • SP 1 complexity
  • Confirm IRWF image import mapping requirements meet all the needs of IDEP
  • SP 1 complexity
  • Confirm key relevancy metadata and availability via query mechanisms
  • DICOM
  • XDS
  • SP 1 complexity
  • Confirm key hanging protocol metadata and proper import mapping
  • SP 1 complexity
  • Mapping Table - DICOM Header of Prior to Local HL7v2 OMI
  • draft exists
  • SP 1 effort
  • Mapping Table - MHD DocumentManifest Resource to HL7v2 ORU (MaxUE)
  • draft exists
  • SP 1 effort
  • SP 1 complexity
  • Mapping Table - Object for Import MHD DocumentReference and HL7v2 OMI to local report Resultant Document Manifest (MaxUE)
  • draft exists
  • SP 1 effort
  • SP 1 complexity

Topics/Debates

  • MaxUE: Debate scope details (then fix profile details to match)
  • SP 1 uncertainty
  • SP 1 effort
  • Defensive mantra: Reporting is another profile
  • Consider detection of duplicates/versions of the same data to avoid replication cascade; interaction with IOCM
  • some text exists in Concepts X.4.1.8 + Purge Options
  • SP 1 uncertainty
  • SP 1 complexity
  • Which report transports/wrappers for text/PDF are in scope?
  • DIMSE C-MOVE, C-STORE, HL7v2 ORU, OMI, FHIR, ...
  • ASCII/binary blob, CDA1, CDA2, DICOM PDF, DICOM SR, DICOM SC, DICOM SD, ...
  • Note: payload is ONLY text or PDF; other report payload types might be mentioned in Informative annex
  • SP 1 uncertainty

Proposed Minimum Useful Effort (MinUE) Scope

  • Complete the current IDEP supplement
  • Do not include reports in any format -- not even TEXT or PDF
  • Do not include WIA (DICOMweb) query to access prior images (except as reference in Cross Profile Considerations X.6)
  • Retain Importer actor but remove Report Converter actor and transactions
  • Retain Image Purge but remove Report Purge as Named Option
  • (NOTE: removal of the Report Converter actor will be a SIGNIFICANT amount of effort for the editor and will include many changes to sections which have already been reviewed in detail by the TC).

Proposed Maximum Useful Effort (MaxUE) Scope

  • Retain WIA (DICOMweb) query to access prior reports ONLY as reference in Cross Profile Considerations X.6 (no new DICOMweb functionality within IDEP)
  • Retain Report Converter actor and transactions
  • Address TEXT and PDF report formats
  • Retain all other report formats as Volume 1 Informative Appendix with no normative requirements
  • Retain Report Purge Named Option

6. Support & Resources

Canada Health Infoway has been very active in development of this technology and has implemented it across several broad regions, resulting in real-world data and analytics.

HCA in the States has expressed in supporting and reviewing a standard to implement the import and display of external priors. HCA's focus is on the proper display of priors for side-by-side comparison in a most useful and effective manner.


7. Risks

  • Scope creep to closely related clinical issues such as Emergency Department transfer
  • Scope creep related to incorporating additional report formats beyond TEXT and PDF.
  • Scope creep related to incorporating semantic meaning of reports.
  • Scope creep related to additional methods of image and/or report access or image and/or report storage to local systems.
  • Defining too much logic behind "relevancy"
  • consider it as vendor/product differentiation; IHE would define:
  • mechanisms
  • minimum set of metadata to be supported
  • Attempting to rigorously define code table mapping could get messy
  • Legal differences across jurisdictions
  • MHD is in the process of being updated making dependencies on it subject to change
  • Competing FHIR resources: MHD and DiagnosticReport
  • May get feedback in PC leading to late change


8. Open Issues

Scope creeped. Need to rein it back in, especially in the area of report formats. While report formats and transmission is undeniably a mess, the goal of the IDEP profile was never to fix report interoperability, but rather to access at least some of the prior reports. Complete report interoperability should be its own profile.

May even want to consider not including informative appendices in Volume 1 on additional report formats, even if it is a critical gap in products today.


9. Tech Cmte Evaluation

Technical Evaluation:

Effort Evaluation (as a % of Tech Cmte Bandwidth):

  • MaxUE: 27 SP / 40%
  • MinUE: 16 SP / 25%

Candidate Editor:

  • Jonathan Whitby/Vital, with Teri Sippel Schmidt consulting for historical purposes