Radiology Image Sharing Roadmap

Basically we should identify:

• the use cases we think we need to support
• the current tools we have

We can then see

• the gaps (missing tools) we should develop
• the overlaps (redundant tools) we should retire (hopefully none)

The Aspects of Image Sharing is an attempt to think about the key pieces in the use cases that are addressed by the tools.

<WARNING: Half-baked sketch follows>

Aspects of Image Sharing

Image Sharing should address Awareness, Selection and Access of image data.

There are different viable approaches to each of those three aspects of sharing.

Awareness

Knowing there are images that might be of use.

• Sink Approach - depend on systems to push potentially useful images.
• Notification Approach - depend on systems to tell you about the existence of potentially useful images.
• Query Approach - ask systems what images are available
• Subscribe Approach - sort of a cross between Query and Notification

• Note that patient consent will play into awareness, possibly as a precondition/gatekeeper. Patient consent process may influence ease of implementation of approaches above.
• Note: A worklist (reading) is commonly used to make systems/users aware of relevant images.

Selection

Choosing images to make use of.

• Query Approach - evaluate/select based on image details returned in the query
• Sink Approach - see above; trust other system to have selected appropriately
• Notification Approach - see above; select based on image details provided in the notification
• Keep-or-Toss Approach - get all potential images, evaluate directly and toss unneeded ones

Access

Getting the images.

• Sink Approach - see above
  • Pre-caching is one form of Sink.
• Pull Approach - retrieve selected images

Getting the rendering.

• Streaming Approach - rather than sending images, images are rendered at origin and rendering is conveyed (eg, Web client)

Update

How you know about updates to images you have copies of.

• Ignorance/Blind Apathy Approach - No awareness of updates.
• Polling Approach - Requery or re-retrieve images to check for changes.
• Notification Approach - Receive notification that "something" is different. Granularity could vary.
• Delta Approach - Receive list of differences.
• New Copy?

Transport

How the images are conveyed

• Network vs Media
• Synchronous vs Asynchronous
• Whole vs Incremental

Should consider how Transport applies to each of the above Aspects.

Considerations

Different approaches have advantages and disadvantages depending on many factors such as network bandwidth, local storage capacity, image persistence times, stability/changeability of images, immediacy of access needs, quality of image metadata, dependence on new software/systems, configuration/maintenance overhead, security needs, privacy needs, etc., etc., etc.

Do we need to elaborate whether access is direct from the source, or indirect through an intermediary (sync issues)?

What do we have to work with

DICOM Mechanisms

• C-Store
  • push across a typical network

• Retrieve
  • pull across a network, basically a C-Store invoked by the receiver

• Part 10 - Files
  • almost by definition push, asynchronous
  • profiled for a large variety of media: CD, DVD, USB, ZIP, Email, FTP
  • with/without compression
  • includes a MIME type

• Supplement 119 - Instance and Frame Level Retrieve

• Part 18 - WADO - Web Access to Persistent DICOM Objects
  • HTTP based pull across the web

• WG-10 Web Services
  • NADO - Notification of Availability of DICOM Objects
  • QIDO - Query by ID for DICOM Objects

• Supplement 118 - Application Hosting
  • includes mechanisms for accessing objects
  • File based or abstract model

• (DICOM Print)
  • Push to hardcopy

Current Image Sharing Profiles

Profile	Notification	Selection	Access	Update	Transport
"Local" Network
SWF (Mod-PACS)	Sink (C-Store)	Keep	Sink (C-Store)	PIR
SWF (PACS-Disp)	Query (C-Find)	Query (C-Find)	Pull (C-Store)	none
ARI	Query?	Query (C-Find)	Pull (C-Store)	none
TCE (PACS-Dest)	Sink (KIN Tag)	Keep-or-Toss	Sink (C-Store)	none
MAWF
Sneakernet
PDI/IRWF	Sink	Keep-or-Toss	Sink (CD)	none
"Distributed" Network
XDS-I Retrieval (Consumer-Registry-Repository-Source)	Query (SOAP)	Query	Pull (C-Store/WADO)	none
XDS-I Submission (Source-Repository-Registry)	Sink (SOAP)	Keep	Sink (SOAP)	re-publish manifest
Proposed Additions
XDS-I.b	Query (MTOM)	Query	Pull (C-Store/WADO)	none
PDI+	Sink	Keep-or-Toss	Sink (CD/DVD/USB)	none
XCA-I	?	?	?	?
Image Management	?	?	?	Delete/Update/Replace
Federated Storage	?	?	?	?
Notification of Doc Availability (NAV)	?	?	?	?

• Other Referencing
  • KIN
  • CPI, PGP
  • Image Fusion

What are we trying to accomplish

Scenarios/Use Cases

XDS-I Use Cases

The following use case summaries are taken from the XDS-I profile.

1. Routine imaging referral. The referring physician in his office requests that a patient have an examination done at an imaging facility. The physician expects to have electronic access to the imaging report and to the images if needed after the examination has been performed on his patient.
2. Course of Treatment Consult. An emergency physician orders an imaging examination for a patient at his hospital. After reviewing the preliminary report the ER physician decides to consult a surgical specialist at the regional hospital for advice on a course of action. For this, the surgical specialist accesses the images and preliminary report and reviews them in order to propose, on the phone, a course of action for the patient.
3. Clinical Consult. A general practitioner performs a routine imaging referral, reviews the shared imaging report and chooses to send the patient for evaluation by a specialist (e.g. an oncologist). The specialist needs access to the imaging report and full image set produced at the imaging facility where the patient had been sent by his general practitioner to perform the examination.
4. General imaging record access. A patient relocates or decides to change her physician. The new physician needs to retrieve relevant information from the patient record, review its content, including recent labs and imaging studies. A similar situation occurs when a patient is admitted for an emergency and timely access to the patient’s past information is required, including prior imaging studies.

PDI Use Cases

The following use case summaries are taken from the PDI profile

1. Patient/Referring Physician Viewing: Diagnostic and therapeutic imaging data, such as images and reports, is received on media potentially serving multiple use cases. The patient or the referring physician can view the data, either with a viewer application residing on the same media or using a web browser. This data is not necessarily intended as a basis for diagnostic or therapeutic processes, and may just be informative data. For security and privacy reasons, media given to a patient would not contain data of other patients. Refer to section 15.5 for additional security considerations.
2. Healthcare Enterprise Interchange: One or more patients’ data, such as images, reports or complete studies, is received on media to enable a diagnostic or therapeutic care process. Media data are imported at a different site, generally for the purpose of a “second read import” or “reference import”.
   • Second Read Import: Media data is imported to the Image Manager/Archive to be read/over read. In order to avoid data conflicts, key patient/study attributes may need to be reconciled with existing local data. Images and related presentation states can be sent to a Print Composer to be printed.
   • Reference Import: Media data is imported to the Image Manager/Archive and/or Report Repository to become part of the patient history. It may be used as “relevant prior” data for future reads. In order to avoid data conflicts, key patient/study attributes may need to be reconciled with existing local data.
3. Operating Room Viewing: Media data is used to enable diagnostic or therapeutic processes in environments without a reliable network connection. The volume of data can be very large and may contain image data, post-processing results and reports. In the operating room, the surgical staff receives the media and reads its contents using advanced viewing capabilities, which may include manipulating or processing images.

Observed Needs/Failures

Poorly Served Consumers

• Referring Docs quick and convenient access to current images for viewing
  • AMA policy statement on problems with viewing images from removable media; PDI addresses transport needs, though not universally deployed.
  • Consider image access via EHR system.
  • Provide different presentations of same data or provide different data to meet viewing capabilities of EHR.
  • Requirements vary depending on physician role

• Specialists (eg, surgeons) access to current data for processing on specialty-specific applications

• Patient or provider view with patient focus of longitudinal record of imaging studies
  • Avoid duplicate studies; historicals available for review and comparison
  • Patient mobility requires transfer of studies
  • Provide data to PHR systems or accounts

• Distributed workflow
  • Clarify when acquisition, reading and referring are at three different sites
  • Need to address the case when sites are not on the same local network
  • Consider policy and administration issues (eg, ID domains)

• PACS Migration

• Federated PACS or multi-PACS deployments
  • Synchronization of updates and deletes is an issue
  • Delete needs to address both delete of bad data and delete of past-holding-period data
  • Consider offering "last chance to copy" or transfer of ownership
  • Need to manage primarily at study level rather than image instance level

• Data Relationships - don't provide a good map of how data elements fit together
  • Between images/series/studies

• Prior relationships
• Stress-rest images
• Cancer staging
• Pre- and post-surgical

• • Radiology report and image studies
  • Non-radiology reports (eg, lab, path)