Imaging Interoperability: Part 2 -- The 3 flavors of VNA

By Jonathan Shoemaker, contributing writer, Jef Williams, contributing writer

March 15, 2013 -- presents the second in a two-part series on imaging interoperability from Jonathan Shoemaker and Jef Williams of Ascendian Healthcare Consulting. In Part 2, the authors present the key factors that best leverage the functionality of a true VNA. For part 1, click here.

Everyone is charting toward interoperability, a promised land where providers share data across organizational borders with affiliated and nonaffiliated practitioners, groups, hospitals, and health systems. However, in this brave new world, current standard imaging systems will fail to meet the needs of true interoperability and, ultimately, clinical collaboration.

Accountable care organizations (ACOs), mergers and acquisitions, and health information exchanges (HIEs) are all forces shaping the care delivery model across the U.S. The outcomes of these efforts will be hindered, though, by the severe limitations of the existing clinical systems that provide local diagnostic care within clinical departments.

In working with large health systems across the country that are dealing with the challenges associated with adopting this new paradigm of sharing patient data -- specifically, image data -- we have discovered that utilizing the appropriate vendor-neutral archive (VNA) is paramount for a successful environment for image interoperability.

In part 1 of this article we discussed the value of VNAs that break customers free of the grip of PACS vendors and provide a platform for sharing image data. Part 2 will present key factors that best leverage the functionality of a true VNA to meet the goals of the organization.

Image data interoperability

Many clinical systems do not have the ability to ingest and disseminate imaging data in a dynamic method that shifting care-delivery models require. The absence of an associated order or enterprise master patient index (EMPI), non-DICOM formats, and hijacked data-field content are just a few of the variables that create chaos in most PACS environments, and thus create a cacophony of problems with interoperability.

ACOs and HIE implementations continue to progress faster than PACS or imaging system vendors can innovate to sustain not only the dissemination of data but, more importantly, the ingestion of the data into a diagnostic application without requiring human intervention to create or modify the required metadata. This manual process, utilized in many organizations, to manage interoperability, especially externally, is inefficient, risky, and costly (none of which will help an organization succeed in the new paradigm of healthcare delivery).

As covered in part 1, the vast difference between the VNA vendors' offerings (other than the management of DICOM and non-DICOM data) is the interoperability layer each vendor provides. The system replacement market and specifically departmental diagnostic systems continue to heat up. One challenge of this approach is the associated cost of replacement, including migration, support, workflow modification, and ongoing testing requirements for linked systems.

Replacement systems

In addition, the ability to gain consensus on replacement systems can be a challenge. The industry, like many others before our time, is moving toward modular architecture at the application layer. Much like the practice of "bring your own device" (BYOD), we see a move toward best-of-breed diagnostic tools and viewers.

This strategy allows departments to deploy systems that support specific department workflow, while the underlying interoperability platform manages all storage, dissemination, ingestion, and data flow to support not only internal application requirements but also ingestion of external data into the clinical systems. This environment provides physicians the opportunity to access all relevant clinical data -- independent of acquisition location or type -- within the clinical application at the point of care.

Which solution you choose to provide access and data-flow interoperability will depend upon your facility, your organization's goals and direction, technical requirements, functional requirements, and clinical system data flow. The solution that helps your enterprise meet the demands of interoperability will likely utilize multiple vendors, unlike the first generation of PACS that brought turnkey systems from acquisition to archive.

As you craft a solution, it is important to align your facility with a VNA vendor that can manage your internal requirements (functional, technical, and operational) while also positioning your organization for simplified integration into any future exchange models, including both private and public exchanges.

3 VNA interoperability models

The case for using a VNA is well-established at this point with so many articles, presentations, blogs, and thought-ware. We have participated in a number of different approaches to utilizing a VNA for the purpose of interoperability. Of these various methods, three models seem to be emerging as trends.

Each is viable, but each is not equally viable for every organization. Vetting the appropriate model is a critical step that requires internal discussions across multiple disciplines and strata within the organization. Each of these models, however, provides a solution that solves the interoperability dilemma beyond PACS and DICOM.

Local VNA

This is the easiest model, requires the least amount of outside collaboration, and yet positions an organization for sharing data. Implementing a local VNA (either onsite or cloud-based) provides a platform that manages and consolidates storage and management for DICOM and non-DICOM data across the enterprise.

The local VNA solves data-flow obstacles and challenges across enterprise clinical systems that don't inherently like to share (inbound and outbound) data. This model of VNA manages data across the enterprise while providing the ability to tie into external exchanges and ACO participants. This allows for interoperability beyond the department and even the enterprise while enabling departments to pursue (or avoid ripping out) best-of-breed clinical systems that may not have the interoperability functionality that a VNA provides.

Local VNA with co-located regional VNA

In this model, a local VNA manages the primary image data onsite while the secondary copy is replicated into a shared regional VNA. This model requires a greater level of collaboration across nonaffiliated providers but removes the perceived risk of a shared archive. The local VNA can be configured to solve the internal data-flow issues while also managing a second-tier, offsite copy.

A regional VNA (typically cloud-based or application service provider) can be shared across providers or managed solely by a single organization that provides a subscription-based solution for other interested parties that want to meet image exchange requirements as defined in meaningful use, while simultaneously storing a secondary copy of the image offsite.

Regional VNA

The regional VNA model receives store-and-forward objects from the clinical systems into a regional archive. This method, while the least costly due to distributed ownership, conversely can introduce a greater risk that stored objects are static and not synched to the local copy on the PACS.

While it's the easiest VNA model to implement, the regional VNA's data flow may not meet all of the needs of your organization, as architecture and management are handled by committee and must be vanilla enough to provide a common denominator for nonaffiliated providers.


The old phrase "any image, anywhere, anytime" seemed simple seven years ago when every PACS sales specialist was touting "enterprise imaging" slogans. That statement, however, was based on the assumption that images were distributed inside of a controlled, DICOM environment -- and within radiology.

Enterprise imaging now means images across PACS and silos, departments, file types, and, ultimately, nonaffiliated providers. As the medical community becomes integrated beyond the walls of the enterprise, it will become increasingly complex (and costly) to distribute and ingest data in a robust, automated way. Utilizing VNA as an interoperability platform can lead your organization to success and, at the same time, meet the demands of interoperability and reform.

We're not sure what the promised land looks like, exactly, but we know it's where we're all headed. And we're certain we don't want to get stuck in the desert.

Jonathan Shoemaker and Jef Williams are frequent speakers and writers on healthcare technology topics and enterprise imaging solutions. Jon is a senior consultant and Jef is vice president at Ascendian Healthcare Consulting. You can contact them at and

Copyright © 2013

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