Diagnostic imaging concepts with multiple body parts imaged as part of one procedure code

In the international version of SNOMED CT there are a lot of concepts that are supporting the DI use cases. Additionally, Infoway has created since 2014 about 1550 concepts in the Canadian SNOMED CT Extension to support the DI use case in Ontario and in Canada. The concepts we created were precoordinated concepts, which included left, right and bilateral body sites. They also included single body site and multiple body sites. While most are a single modality, many are multiple modalities.

Since about a year, SNOMED international is enhancing and refining the terminology, their models and guidelines. They are stricter on the international scope for international inclusion. A concept can be added to the international version if it meets different criteria, like the 1. URU criteria (Understandable, reproducible, useful) 2. Does it support a use case that has an international scope? If the answer is yes, then the requestor must provide supporting and/or reference information that support the use case.

If the content requested does not meet the international usage criteria, it will not be added to the international version. Likewise, in Canada, our request for change process being based on the same criteria, if the use case has a national scope, we will add the content in the Canadian extension, if not, it will not be added.

The folks from Regenstrief have been working collaboratively with RSNA to unify terms for radiology procedures. From the Regenstrief website:

"The Radiological Society of North America, owns and maintains the RadLex™ medical terminology for radiology, and the Regenstrief Institute Inc. owns and maintains the LOINC® terminology standard for medical tests and measurements. Creating standardized radiology procedure names will improve the quality, consistency and interoperability of radiology test results in electronic medical record systems and health information exchange. The goal of the project is to produce a single unified source of names and codes for radiology procedures with a cooperative governance process."

The LOINC/RSNA Radiology Playbook is the product of the collaboration between the RSNA and Regenstrief Institute, Inc to develop a unified model for naming radiology procedures. The playbook is available for download from Regenstrief here .

If you are interested in learning more about how LOINC can be used for Radiology, I would encourage you to join the LOINC Clinical Meeting by webex on March 8-10. More information about it can be found in the events calendar.

Regards,

Lorie Carey
Infoway Standards SME

The International release of SNOMED already contains some procedures for combined body parts, e.g,:

browser.ihtsdotools.org/?perspective=full&conceptId1=429864007
browser.ihtsdotools.org/?perspective=full&conceptId1=433761009

which are:

"Computed tomography of thorax and abdomen with contrast (procedure)"
"Computed tomography of thorax, abdomen and pelvis with contrast (procedure)"

and these are also present in various other schemes:

www.ipcmr.org/html/IPCMRCodes.html#7195-0871
www.ipcmr.org/html/IPCMRCodes.html#5832-6961

Using the IHTSDO browser you can see how they have defined these in terms of the parent/child relationships as well as the multiple sets of Method and Procedure Site -Direct combinations (and Using Substance).

David

PS. A lot of these were already in the Canadian extension, were they not? The UK have similar requirements (as reflected in their NICIP codes, which are mapped to SNOMED).

Hi Cezary,

I agree that SNOMED CT turned out not to be convenient for DI procedures coding. And I agree that we don't want to re-invent the wheel. RSNA has done a lot of work trying to solve this issue and I invite you to check Radlex Playbook (I'm sure you know it already). Look at the following links: www.rsna.org/RadLex_Playbook.aspx
and if you want to have the real feel: playbook.radlex.org/playbook/SearchRadlexAction
I am not aware of any site using it though in Canada, and don't know how easy or realistic it would be to implement it here.

Thanks,
David

I am not able to provide any pointers to academic documentation on the topic but can comment based on experience and on what we have been doing as a company (Leafsprout) in other Canadian jurisdictions.

In the realm of diagnostic imaging procedure codes, SNOMED CT does indeed seem to be misaligned with the inner workings of radiology on both the clinical side (after all "Chest Abdomen" or "Abdomen Pelvis" procedures are quite common radiological procedures) as well as the technical side (the DICOM standard has supported composite body parts from the get-go, e.g., CHESTABDOMEN, ABDOMENPELVIS, CHESTABDPELVIS were defined for a reason -- there are real-world imaging procedures for those). Enhancing SNOMED CT looks to me like a possible but expensive path that may or not be worth it depending on the expected return on investment. Most jurisdictions around the world tend to use CPT-like approaches to DI procedure codes in which the emphasis is put on the ability to unambiguously identify a real-world clinical event/procedure rather than on combining the identification aspect with the descriptive/hierarchical/relationship-management aspect, the latter aspect using intricate concept-based modelling approaches with their own limitations that you are facing.

Getting the procedure codes under control is, in my opinion, of paramount importance to any health system. After all, these codes address key facets of healthcare delivery: the clinical perspective, which is understanding what medical event took place -- procedure code tells us what was done, precisely; and the administrative/financial perspective, which casts light on how much money was spent/made in the process -- procedure code ultimately tells us how much it cost. From what I have observed over the years, the rule of thumb is that the closer the procedure codes stay to the reimbursement model, the more aligned the two aforementioned facets of healthcare are, and the more value you can get down the road from using them (including tackling more advanced topics like population health, analytics, etc). So perhaps there is no reason to be reinventing the wheel here by extending SNOMED CT to express DI procedure codes that have already been in use for many years now. What's needed is a normalization/canonicalization of the various vernaculars currently used in the province so a global set of codes can be devised.

For what it is worth, this is what we've done in BC. It seems to be working so far. Our systems manage and enforce the authoritative set of diagnostic imaging procedure codes used throughout the province (~3k procedure codes). This is the so-called global/provincial set. Every single DI study and report is assigned a code from this set. We also manage various local procedure code vernaculars (many sets of 2k-3k codes each used in different regions) and perform the translation between the provincial set and the local sets which were left intact. The nature of this translation is quite complex and beyond the scope of this email (e.g., what happens when a PET/CT exam is brought into an environment where PET procedures are not performed, etc.). SNOMED CT is not used for procedure codes in BC. What is used is a province-controlled and province-assigned set of procedure codes. When at the outset of the project we looked at the problem, jointly with BC, SNOMED CT was not a contender for the procedure set vernacular as the key objectives were:
- alignment with the administrative and clinical needs, including the ability to express the clinical procedures - like "CT Chest Abdomen with Contrast" - that are currently in use in the province (with no dependence on external assigning body for procedure codes)
- ease of translation between existing local terminologies - procedure code sets - used by different RIS systems and the newly proposed provincial-level terminology (see my earlier comment about the local vernaculars staying intact)
- attainability of a working solution involving 90% of BC's hospitals within 12 months

Back to the Infoway perspective: as the CHI Standards Collaborative for Diagnostic Imaging (now DI Working Group) our approach to coding/vernaculars has always been that "the choice of terminology - which is usually an idiosyncratic property of the environment at hand - rests with the affinity domain / jurisdiction that is embarking on a project which requires controlled vernacular(s)". From that perspective, I am a bit confused on what Canadian (cross-jurisdictional) extensions we'd be seeking from SNOWMED CT on the topic of DI procedures. If Ontario is seeking procedure-related enhancements from SNOMED CT, it is certainly a path that could be taken. It may be a long journey though due to the aforementioned alignment issues, or lack thereof, so before embarking on it may be worthwhile to step back and think of the objectives.

Cezary

Hello DI SMEs,
The Ontario DICS project is requesting to have concepts considered for inclusion in SNOMED CT that involves imaging of multiple body parts in one procedure code, For example CT Chest Abdomen Pelvis As we cannot have a one to many mapping for local to SCT we have had these post coordinated concepts added to the CA extension in the past. However, the international guidelines does not allow for such concept modeling. Is there a use case across other jurisdictions for such concepts to be included in the CA extension? Would anyone be able to point me in the direction of supporting clinical/academic documentation for such use cases? Thanks