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A Framework to Aid VNA Implementation

August 27, 2013
by Joseph L. Marion
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VNAs are an effective way to address the clinical content that is growing in importance as EMRs evolve as part of meaningful use

As imaging data throughout the enterprise grows, so does the need for a vendor neutral archive (VNA) for more cost-effective storage. Selecting and implementing a VNA can be daunting. First requirements must be defined, and then vendor claims need to be assessed to achieve a good match. Although this can be challenging, finding ways to simplify and refine the process can be rewarding. A workable framework could help better define requirements and assess alternatives.

Framework objectives include:

  • Improving the ability to more thoroughly define VNA requirements;
  • Enhancing the mechanism for assessinga vendor’s match to a site’s requirements;
  • Providing a set of common definitions of VNA functionality; and
  • Encouraging users and vendors to use the framework.

Framework Proposal

This article proposes a workable VNA framework by identifying VNA elements and testing them with VNA vendors and users for substantiation. Starting with the constitution and delivery of services, a draft framework was circulated among a number of vendors and users for comment. Figure 1 illustrates the framework. An explanation of the framework parameters and examples of using the framework follows.

Figure 1.

The primary core of a VNA is a services layer that manages storing and accessing variable content hosted on various computer storage infrastructures, and accessed by viewing applications. There are various approaches to acquiring the technology, including capital and operational models.

Axis definitions are summarized as follows:

Services: Services represent the system processes for anaging content and infrastructure. Vendors themselves may provide services, or resell the services of others. Services definitions are as follows:

System Monitor: Monitoring services monitor system operation, notify of impending problems, and perform system auditing and reporting.

Data Integrity: Data integrity assures data is stored correctly.

Image Life Cycle Management (ILM): ILM rule sets manage how long data is stored to satisfy the legal retention period, as well as retention of minors, mammography, and environmental studies.

Workflow: Workflow rules address access rights and pre-fetching rules. Application workflows address how patient demographics are matched to images.

Clinical Abstraction: Data from multiple sources may require manipulation for storage. For example, some systems may include proprietary data sets that the VNA will need to handle as part of storing the data, enabling data that is accessible from the VNA without being tied to the originating device.

Data Migration: The ability to handle how data is converted, either into the VNA or exported to another environment, is an important aspect of a VNA Service.

Content: The Content axis addresses the extent of content managed by the VNA. Departmental solutions require only DICOM images, whereas enterprise-scale solutions may address non-DICOM and other industry standad formats (JPG, TIF, BMP, MINT, etc.) as well. In multiple entity environments, support for the cross-enterprise document sharing of images (XDS-i) and cross-enterprise sharing of documents (XDS), Integrating the Healthcare Enterprise (IHE) profiles, and health information exchange (HIE) standards may be necessary.

Infrastructure: The Infrastructure axis represents a range of equipment environments. The simplest is a software-only solution, while others may address both a software and hardware (turnkey) solution. Hardware can be physical or virtual, more sophisticated applications may be replicated or redundant hardware. Cloud-based services are growing in importance, and may include private and public clouds.

Accessibility: Independent access to stored content can make it accessible to a number of different users for multiple viewing purposes. Access independent of the originating system is important when the originating system is not available. New applications such as advanced visualization might access images from a VNA instead of an existing PACS. There can be diagnostic applications, clinical viewing, or universal image access such as through a linkage to the EMR. Mobility is increasing through “zero footprint” viewers that can be launched from a number of portable devices such as tablets or smart phones. Adding viewing capability to facility Web portals for access by either clinicians or patients will expand clinical content accessibility.

Total Cost of Ownership (TCO): TCO addresses options for financing and operating a VNA. Local applications on existing hardware favor a capital approach. There may be associated setup or professional services fees. Alternatively, the fee-for-service model is popular, either as a cost per study, or a cost per amount of information stored (gigabyte or terabyte). Some services only charge an “ingestion” fee, while others have additional fees for long term storage. Subscription fee models essentially level-load charges over a fixed period (monthly) for an estimated volume level. Fees may vary month-to-month if volume varies.