Essential Ingredients of a PACS-Neutral Archive

Whether its name is PACS-Neutral or Vendor-Neutral, the Enterprise Archive whose major feature is data exchange between disparate PACS is sometimes hard to identify.  The situation is similar to the Christmas shopper trying to differentiate the real designer handbag or watch from the fakes.  Simply publishing a list of the “real” Neutral Archives is not sufficient, because products change, and entry to the list could be as easy as making a few key changes.  A better way to identify the real Neutral Archive is to use a carefully conceived check list.

I came across just such a check list at this year’s RSNA.  It was a piece of booth literature created by Acuo Technologies.  While I completely agree with a good deal of the Acuo list, I have made some additions and changes to make it my own (and the elements from the Acuo list are reprinted here with their permission).  I offer the following check list to those that are interested in understanding what constitutes a fully functional Neutral Archive.

Bi-Directional Dynamic DICOM Tag Morphing – On-the-fly conversion/mapping of data elements in a DICOM header to facilitate data exchange between disparate PACS.

DICOM - Full conformance with latest DICOM SOP Classes (SCU and SCP) with no exceptions.

Non-DICOM – Methodology for accepting and managing non-DICOM data objects, most notably J-PEG and PDF objects, preferably via Web Services and optional support of WADO for viewing .

ILM Methodology – Intelligent Information Lifecycle Management (ILM) – data movements internal and external to the system based on meta data associated with the study data (study date, study type, patient age, etc.) Separate ILM strategy for each organizational node (facility, department) .  Automated, user-defined Data Purge mechanism with manual supervision. Node-specific Retention Flags that would over-ride a Purge operation.

Unique ID – Ability to make the ID associated with incoming data  unique (throughout multi-facility enterprise) without need for Master Patient Index (MPI).  Internal Pseudo-MPI capabilities tie individual facility MRNs to the same patient (in a multi-facility organization).

Pre-fetching / Auto-routing – HL-7 or DMWL enabled Pre-fetching of relevant prior data being managed by the Neutral Archive and Auto-routing of that data to the appropriate department PACS either directly or through the Archive’s local Facility Cache.

Flexible Architecture Server and storage Hardware Agnostic, Primary and Secondary Mirrored Subsystems,  Active-Active or Active-Passive modes  with Automated Failover and Automated Reconciliation between the two subsystems.

Data Integrity -  Synchronized updating of meta-data (patient/study level changes). The Neutral Archive will propagate updates received from RIS(s) or via manual update to all destinations that received studies in order for all available patient information to stay in sync.

Storage Reclamation – Ability to reclaim storage space following media migration or data purge.

Data Compression – Preferred compression syntax is JPEG 2000 Lossless but capable of negotiating any DICOM supported compression syntax.  No proprietary compression syntax.

XDS-I Manifest – Automated creation of XDS-I manifest for all data objects ingested by the Neutral Archive, with Optional XDS-I Registry and Repository available when needed.

Transaction Logging – HIPAA compliant Logging and Reporting by Organizational Node

Experience – Neutral Archive vendor has years of experience in the business: Millions of studies migrated between all of the major PACS, a dozen or more instances of the Neutral Archive deployed

The reader will notice that I did not include on the list one of my favorite items: the UniViewer.  While a unified multi-modality viewing application is a highly desirable option, and the key to image-enabling the EMR, I don’t think the viewing application itself needs to be an integrated component of the Neutral Archive.  That’s because it can easily be a free-standing add-on.  There are a number of zero-client, server-side rendering display applications that run on their own server platforms and simply access the image data being managed by the Neutral Archive.  There seems to be no advantage to forcing the Neutral Archive vendor to pick one at the expense of the others.  It seems totally appropriate to let the Health System make this selection, knowing that there are no complicating interface issues.

A final comment…The above list is by no means a complete description of, or specification of, a PACS-Neutral Archive.  Gray Consulting has created a very comprehensive Request For Proposal document that accurately defines a Neutral Archive.  The Technical section of this RFP contains 22 categories of questions that span 120 pages.  Anyone interested in a thorough investigation of this subject is welcome to contact Gray Consulting.