IT spotlight: State-of-the-art VNA

Medical image storage has become complex: People expect easy access to images, and with the proliferation of electronic health records (EHR), this includes physicians. Vendor-neutral archive (VNAs) technology provides a single consolidated enterprise image management system, eliminating silo storage of specialized images.

Since its inception, VNA technology has been promoted as the heir apparent to conventional PACS storage. If the proliferation of commercial VNAs exhibited at RSNA 2014 is an indicator, its time has come. 

Boriz Zavalkovskiy knows a lot about VNAs. He was part of a team at the Mayo Clinic that architected and developed the integration requirements for the very first VNA, a healthcare enterprise initiative undertaken in the early 2000s. Today, as the IT director of imaging systems and services at Stanford Health Care, Stanford, CA, he oversees the implementation and utilization of the enterprise’s Radinformatics talked with him about the current capabilities of VNAs, stumbling blocks that still need to be overcome and factors that will stimulate widespread adoption.

The main components of a VNA are an archive that has the ability to store and distribute the images it receives in a standard format and the software that makes this happen accurately, intelligently and expeditiously. The infrastructure of the software system incorporates components for data integrity, content management, image life cycle management, application workflows, image delivery and viewing and system self-monitoring.

Two kinds of VNAs

Zavalkovskiy identified two distinct types of VNA image archival systems: One is designed from inception to be a stand-alone neutral archive, a true VNA, and the other is built upon an existing PACS image storage platform. “They are differentiated by the fact that a true VNA does not have any workflows associated with clinical image management and workflow,” he explains “Rather it has a workflow for image archiving, retention, and distribution, in compliance with DICOM and the other standards of the images it contains.”

VNAs built upon an existing PACS platform have expanded their scope to include DICOM images of other medical specialties and to be able to store non-DICOM images that are, as Zavalkovskiy explains, “DICOM-ized”, essentially clothed in a DICOM wrapper. “If a VNA cannot be used independently of a PAC system, it has been designed as an extension of the existing PACS platform,” he specifies.

The VNA in use at Stanford accommodates any imaging standard format—such as JPG, TIFF, AVI files, and MPG files—that are commonly used in the worldwide web and a vendor-neutral DICOM archive. “If a VNA is DICOM-based, it doesn’t have standards for some types of images, and this will leave a large portion of an enterprise’s clinical practice unaddressed,” Zavalkovskiy says. “A VNA that creates a DICOM wrapper around the image—DICOM-izing the file—works from the perspective of storage and distribution, but it does not restore the image to its original format.”

The debate over DICOM versus true VNAs recalls the debates associated with reversible and irreversible image compression, he notes. There was a great deal of debate and concern regarding the stage at which a lossy compressed image would cease to be diagnostically useful versus lossless compressed images, which retained their original data integrity.

 Zavalkovskiy compares the DICOMized image to the lossy compressed images of the earliest PACS. It can be retrieved, but it cannot be restored to its original format, a deterrent to a clinician who needs to reference the original format. Accurate measurement isn’t possible, because the spatial resolution of a DICOMized image does not replicate the original.

He expects that this technical issue will be resolved at some time in the future, but for now, hospitals that use a DICOM-based VNA may have to to retain storage archives of non-DICOM images that could be needed in their original state.

The role of software

Although the truly enterprise VNA encompasses the ability to archive all medical images from all the systems that exist in the enterprise, it is not sufficient by itself. To be clinically useful, it has to integrate with the enterprise hospital information system and link to the episode of care, and that is accomplished via software.

The software needs to be able to accommodate storage, distribution, modality worklists and DICOM routing. Another factor to consider: retention of image policies differ from state to state. A VNA also should be able to mark exams appropriately for deletion based on local institution and state regulatory policies.

Beyond those basic capabilities, VNA software in an ACO-type environment for which health information exchange is important must have the ability to accurately match patient information being transferred to the patient file in the recipient organization. Currently, there is not much demand for what Zavalkovskiy calls “the global archive.”

The success of the VNA within an enterprise environment is determined by its rate of use, and at Stanford, the VNA is very successful. In order for the VNA to have reach outside the “enterprise bubble”, significant societal and healthcare economics changes will have to occur, Zavalkovskiy says. The global VNA has yet to find a market.

Financial incentives for radiologists to become more productive and radiology departments to be more efficient drove the adoption of PACS, Zavalkovskiy says. A shortage of medical transcriptionists and opportunities for cost-reduction drove the adoption of speech-recognition dictation systems. Much as a global archive is needed—as well as transparent image exchange among VNAs—neither will happen without similar drivers, he says.

VNA of the future

The very first VNA was developed to eliminate the costs and problems associated with nine different PACS and their archives used by Mayo Clinic. Zavalkovskiy, who was a systems development manager at Mayo Clinic Scottsdale, said that after the organization failed to find a vendor willing to develop a custom VNA, it funded developing one of its own in the early 2000s.

“Health information exchange is being driven by incentives from the federal government and is at different stages of deployment and different levels of success,” Zavalkovskiy says. While the transfer of textual data exchange is a relatively easy undertaking, the transfer of image data is considerably more complex and expensive. With imaging, terabytes of data are involved for individual patients.

“This alone can create difficulties for wide area networks (WANs) as well as for some underpowered local area networks (LANs),” he says. As a result, DICOM CDs and patient-specific individual image transfer are the most prevalent forms of image exchange, but manual intervention is needed to ensure that images are added to the right patient file and associated with a specified episode of care.

Zavalkovskiy points out the inefficiency of these transactions: Essentially, they duplicate image records, one in the originating archive and one in the recipient archive. Neither is the additional information that is generated recorded in patient’s record at both the sender and the recipient institution.

He offers the following example: A Chicago-based IT contractor has a CT chest image performed while working in Seattle, and the exam’s images are added to his Chicago-based patient file. Subsequently a resident in Seattle performs 3D reconstruction on the image set and identifies a finding of significance. How will this information be conveyed back to the Chicago hospital and caregiver?  Currently, this does not happen seamlessly and automatically.

Accountable care organizations (ACOs) have the potential to drive the integration of global VNAs with EMR systems and widespread diagnostic image transfer, Zavalkovskiy says. When healthcare institutions stop being paid for relevant duplicative exams that have been performed at other healthcare institutions, the efficiency and cost savings available with image exchange will become essential drivers.

Global VNAs are on the road to universal adoption, he believes. Meanwhile, when a hospital is ready to replace its PACS storage system, Zavalkovskiy strongly recommends replacement with a truly enterprise VNA. He speaks from experience.

Cynthia Keen is a contributing writer for