Vendor neutral archive (VNA)

Vendor Neutral Archive (VNA) is a medical imaging technology in which images and documents (and potentially any file of clinical relevance) are stored (archived) in a standard format with a standard interface, such that they can be accessed in a vendor-neutral manner by other systems. This terminology is used as distinct from a traditional Picture Archiving and Communications Systems (PACS), although there is debate about where the boundary between a VNA and a PACS lies along the continuum of their common features.

The simplest definition is “a medical device that stores medical images in a standard format with a standard interface, such that they can be accessed in a vendor-neutral manner by other systems”.

So-called “vendor neutrality” is implied by the standard format and interface, and the neutrality is with respect to vendor-specific devices that produce or consume those images (e.g., for display, distribution or analysis, with or without specific workflows, such as for radiology reporting, i.e., a PACS).

The exact definition and feature set is contentious though, and evolves as different vendors of VNAs attempt to distinguish themselves from their competitors and avoid being excluded, and customers express desires ranging from pragmatic to fantastic.

There is general agreement on the following key features:

• Storage of DICOM images and related composite objects (presentation states, key objects, structured reports)
• DICOM network standard interface for storage, query and retrieval
• Administrative updates and corrections (patient ID changes and study merges)
• Scalability

Each of the following features remain contentious, in the sense that some customers and vendors claim that some or all are fundamental to the concept, but others disagree:

• Storage of objects not directly related to images (such as human-generated requests and reports)
• Storage of non-DICOM content (such as HL7 CDA documents)
• Non-DICOM access protocols (such as IHE Cross-Enterprise Document Sharing (XDS and XDS-I)
• Cross-domain identity and code resolution (patient ID, accession #, procedure codes)
• Dynamic DICOM tag morphing
• Information lifecycle management
• Exclusion of workflow management database content
• Independence from choice of database engine
• Audit trail of access