Presentation of CAD/Annotations/Markups - Detailed Proposal

1. Proposed Profile: Presentation of CAD/Annotations/Markups

• Proposal Editor: Michael Planchart / Peter Maton
• Profile Editor:
• Domain: Radiology

Summary

Display of CAD/Annotations/Markups on images is unreliable, with potential for loss of information and disruption of workflow.

A significant cause is that different products use different mechanisms when creating these graphics, and the PACS/display stations handle this inconsistency and variation poorly.

DICOM has provided both general tools (GSPS, KIN, Overlays) and application-specific tools (Chest CAD SR, Colon CAD SR, etc.) for such purposes.

A Markup Profile could define which mechanisms should (and which should not) be used by Creators for different cases and types of markup and define which mechanisms and behaviors compliant displays must support.

Healthcare providers are showing continued interest in the use of CAD to improve the detection of cancer nodules and other abnormalities in Chest X-Rays.

The Problem

CAD and clinical processing applications create processed images with annotations/markups. Different products are using different mechanisms for the markup, e.g.:

• burned into the DICOM image,

• encoded in the image overlay,

• encoded in separate presentation state graphics,

• encoded in a separate SR,

• rendered onto the image in a separate JPEG

With so many mechanisms, display systems support some of them poorly or not at all, so workflow is disrupted and key information may be inaccessible.

The variability also makes it very difficult to create robust hanging protocols.

Key Use Case

• Use Case #1 DR/CR Chest X-Ray Lung CAD - Results are Stored at Image Archive (PACS):

Chest X-Ray Lung CAD devices process the digital images of AP/PA projections (frontal chest) obtained from the DR/CR modalities in order to detect nodules or abnormalities and to identify and mark the coordinates of the regions of interest (ROI).

The CAD processed output shall be delivered as a DICOM Chest CAD SR SOP Class to the Image Archive (PACS server).

The following features shall be provided by the Image Display:

• The Image Display shall provide the means of toggling on off the markers atop the source image,
• the markers should be off by default on the PACS viewing workstation,
• the Chest CAD SR Results should be independently toggled from other overlays.

Standards & Systems

• DICOM – Chest CAD SR SOP Class
• Existing IHE Actors and Transactions

Technical Approach

Create a new profile for the implementation of the Chest CAD SR SOP Class as the one-way approach for the integration of Chest CAD devices with Image Displays.

Existing actors

• Acquisition Modalities (e.g. CR,DR,DX)
• Image Creator (e.g. Chest CAD Device) - CAD devices can create an additional image that is derived from the source image and burning in the markups.
• Evidence Creator (e.g. Chest CAD Device) - When the CAD device creates the resulting Chest CAD SR.
• Image Display (e.g. PACS Image Viewing Workstation)
• Image Archive (e.g. PACS)

New actors

• None identified.

Existing transactions

• RAD-10: Storage Commitment

         Actor: Acquisition Modality (CR and/or DR)
         Role:  Make requests for storage commitment to the Evidence Creator for the images, 

         Actor: Evidence Creator (Chest CAD Device)
         Role:  Make requests for storage commitment to the Image Manager for the images, and Evidence Documents (Chest CAD Structured Reports), 

• RAD-26: Query Reports

• RAD-43: Evidence Documents

• RAD-44: Query Evidence Documents

• RAD-45: Retrieve Evidence Documents

New transactions (standards used)

• IHE already has defined the transactions that would be required by this proposed profile.

Impact on existing integration profiles

• There are no anticipated impacts on existing profiles since none of them address the use case described.

New integration profiles needed

• Presentation of Chest CAD Annotations/Markups.

Note: Ideally a more generic approach could be chosen but since DICOM defines separately each CAD Structured Report and the variations of use cases between Chest CAD and Mammo CAD there is no easy way of doing this.

Breakdown of tasks that need to be accomplished

• Validate the described use case as the "one-way" approach to integration of Chest CAD results with Image Displays,
• Determine from the collection of existing IHE transactions which could be leveraged,
• Create corresponding profile

Support & Resources

• CAD Providers:
  • Riverain Medical

• Image Display Providers:
  • Agfa
  • ASPYRA
  • GE
  • McKesson

Risks

Currently there are no risks identified. DICOM has the standard defined for the presentation of Chest X-Ray CAD/Annotations/Markups which is the Chest CAD SR SOP Class.

Albeit there are many other approaches the industry wide consensus for the interoperability between CAD devices and Image Displays should be the DICOM SR.

The Profile would simply provide a clear approach to the vendors of how to interoperate with Chest CAD devices as Evidence Creators.

Open Issues

• Use Case for DR/CR Chest X-Ray Lung CAD - Results are not Stored in Image Archive (PACS):

Many radiologists do not want to store the CAD results in the PACS server citing various reasons (e.g. legal, network capacity). CAD devices are not designed to store persistent objects and rarely have the Query/Retrieve SCP service capability, and if they did the image displays are not designed to poll other sources aside from the PACS server for images related to a patient and/or study under review.

IHE would have to decide whether or not a different profile would address this specific use case.

• Other Use Cases for CAD variations consideration:

Another consideration would be for the definition of a more generalized profile that would include more alternative CAD variations. DICOM has addressed each SR separately albeit there are similarities between them since they are derived from the Mammo CAD SR SOP Class.

Tech Cmte Evaluation

<The technical committee will use this area to record details of the effort estimation, etc.>

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

• 35% for ...

Responses to Issues:

See italics in Risk and Open Issue sections

Candidate Editor:

TBA