Imaging and the PCAST (President's Council of Advisors on Science and Technology) Report

Summary: Is the national health care IT standards agenda going to ignore the lessons of the past and the progress made so far? If so, what impact will it have on imaging?

Long Version:

This morning I was sent a link to a report on Realizing the Full Potential of Health Information Technology to Improve Healthcare for Americans: The Path Forward released on December 8th, 2010 from the President's Council of Advisors on Science and Technology (PCAST). There is a video available of the press conference at which it was released, as well as some older video from July 16th, 2010 of a panel discussion about some of its content. The noble goals that the speakers in the videos espouse seems to be somewhat at odds with the actual content.

Already various healthcare IT bloggers involved in standards development and deployment have commented in some detail about the technical content of the report, including Keith Boone, John Halamka, and Joyce Sensmeier.

These bloggers all seem slightly dismayed that the report seems to dismiss, or at least not give adequate recognition to, many existing efforts that are well underway. In my own review I see that HL7 is barely acknowledged, CDA is attributed to the ONC rather than HL7, IHE gets a passing mention only, and there is no mention at all of XDS, XUA, XCA, BPPC or any of the many other IHE efforts to move information back and forth across communities.

Instead, amongst the other content of the report that seems pretty reasonable, there is the unsubstantiated assertion made that "document" or "record" oriented interchange is insufficient and that "tagged data elements" with accompanying meta data are necessary, and a new standard for that needs to be written.

If this were a broad non-technical review, I would have no issue with any of that, but it isn't. It is mostly a broad review, but dives into extreme detail about certain technical issues, including security and privacy and access control solutions, implying that somehow the narrowly focused technical solutions proposed are the only solutions applicable to the broad aims of the overall report. This I find distinctly surprising.

But back to imaging, and what prompted me to write this blog entry, given that the HIT professionals and their organizations are more than capable of speaking for themselves. A surprising aspect of the report is the mammogram use case, starting on page 41.

In this use case, a patient has had mammograms performed at multiple locations, and her current physician needs to retrieve them, given, and I am selectively quoting here, "enough identifying information about the patient to allow the data to be located", "privacy protection information—who may access the mammograms, either identified or de­identified, and for what purposes", and "the provenance of the data—the date, time, type of equipment used, personnel (physician, nurse, or technician), and so forth".

OK, sounds like your standard cross-community access to DICOM images use case, something that IHE RadTech is specifically addressing as a profile this year actually (XCA-I), which involves a relatively simple extension to the existing cross community access (XCA) profile used in the XDS world. Now, I don't mean to pretend that cross-community access control (e.g., via XUA) is easy, nor that reconciliation of patient identity across communities (PIX) is easy either. Merely to point out that the problems in this area are lack of deployment and shared infrastructure or the incentives to build such (as the PCAST report rightly emphasizes elsewhere), and NOT lack of standards. We already have standard mechanisms to provide images with the level of completeness and quality required for the specific use case, ranging from pre-windowed downsampled lossy compressed images for undemanding review applications, through to the full set of diagnostic quality images required for more sophisticated uses.

Since we already have standards to do exactly this, it is perhaps not the ideal use case for PCAST to pick. The idea that a mammogram image (or set of four standard view images, all 40 to 120 MB of them) can somehow be treated as a single "data element", like say, a single blood glucose value, flies in the face of decades of experience of an entire industry.

That said, if the example had been a "tagged data element" such as the BI-RADS category from the body of a series of mammography reports from different locations, the example would have been more plausible. Indeed, the notion of being able to query and retrieve that part of the content of what would traditionally be handled as entire documents is very attractive on the face of it, and undoubtedly a desirable goal, though one that does not require rejection of the traditional structured document oriented paradigm to achieve. Nor does the report address the key barrier to adoption of structured as opposed to unstructured content to facilitate data element extraction and query, which seems to be a combination of a lack of tools and incentives to author structured content in the first place.

Regardless, a new "tagged data element" approach is not a pre-requisite for progress, and we do not need to wait for new standards to be promulgated for this before realizing most, if not all of the benefits of connectivity and interoperability.

Nor frankly, do we need to be able to query across enterprises at a particularly granular level, say for which operator performed a study, or what kVP they used. The metadata envisioned by IHE is very narrowly focused for this reason, and the notion of exposing "all available meta data", whilst theoretically possible, has enormous performance implications. This is certainly not the biggest fish to fry in the short term.

The entire continuum from images through documents to "atomic" data elements share common barriers ... lack of any connection at all between enterprises and communities, lack of deployment of existing standard mechanisms for patient identity reconciliation, and lack of deployment of existing standard mechanisms for provisioning and controlling access.

Even on the access control front the report seems to ignore existing standards and infrastructure. After a basic tutorial on security principles, tied to the "tagged data element" concept, the mammography use case is revisited from this perspective, on page 51.

To paraphrase, an access control service authenticates the clinician, assures the patient has granted them access, and provides the locations of the encrypted mammography images, and supplies the necessary decryption keys. Then, and I quote, "in this and all scenarios, data and key are brought together only in the clinician’s computer, and only for the purposes of immediate display; decrypted data are not replicated or permanently stored locally".

Really ? It is hard to imagine how to enforce that. And how practical is it, given that you generally need a pretty clever viewer if not an entire mammography workstation or plugin to your PACS viewer to effectively utilize a mammogram ? Given that the standard of care currently seems to be to import outside studies into the PACS for use as priors and for distribution throughout the enterprise to allow them to be used with the (expensive and advanced) tools that expert physicians are used to using, the report's proposal seems unrealistic.

Though the mammography imaging use case almost reduces to the absurd the notion that this form of restricted access without local importation is workable, even in the case of a local doctor's EHR, I would imagine that they would want to record even a simple data element, such as the blood glucose, imported from outside systems, rather than be restricted to accessing them on demand only. Even to manifest the prior values in a graphical form or as a flow sheet, which would seem highly desirable for enhanced decision making, would be very challenging if "outside" data points could not be persisted locally, permanently. Indeed I dare say there might be a record keeping requirement to maintain such information.

Contrast the PCAST report's proposal with what is already well standardized; as described before with XDS-I used in conjunction with XCA and XUA and PIX mechanisms, the XDS-I Imaging Document Source would provide the DICOM images to the clinician once authorized, encrypted in transit but not otherwise, via the protocol and in the format requested by the recipient, and importable into a "real" mammography display system in the normal manner. All without having to have every DICOM-compatible viewer or display system be updated to support some mythical new "universal language" based on"tagged data elements" and without being prevented from importing the images for transient or persistent use as is necessary to provide quality care. See John Moehrke's blog for a primer on what security features IHE has to offer.

Anyway, without getting too strident about, at best I find some of the technical content of the PCAST report a disappointment. At worst, I see it as a distraction from the most important items of the national agenda, well espoused in other parts of the report, which include finding a way to provide the proper incentives to get connectivity adopted in a manner that improves the quality and efficiency of care, preferably in a manner that gives patients granular control over access to their information.

Also surprising is the choice of the mammography imaging use case as the poster child for PCAST, given that the ONC has essentially ignored imaging in its initial stages of "meaningful use" probably quite reasonably in terms of return on investment, but much to the chagrin of the various professional societies, judging by the ACR/ABR/SIIM/RSNA joint comments and MITA comments. When later stages of "meaningful use" get around to imaging, they will probably emphasize reporting, decision support and avoidance of unnecessary imaging (probably much more important goals), by which time, even in the absence of specific incentives, distributed cross-community image exchange via the "cloud" will probably be commonplace. One could certainly leave the RSNA show a week or so ago with the impression that this is a solved problem, and high time too.

David