PACS has been the single most successful global healthcare IT initiative, but as systems have aged and the initial contracts have reached the end of their term, growing numbers of customers have looked for replacements.
PACS users have faced difficulties in extracting data from one system and putting it into another vendor's package. This process is referred to as data migration. Some of these migration problems were related to poor data input by customers, or so-called dirty data. Other problems were due to the use of private tags, because as DICOM evolved, standard tags were often not available at the time of data entry. The use of proprietary compression to help support faster displays has also caused problems.
Difficulties in data extraction led to a lot of scare-mongering about switching suppliers, likening PACS replacement to going through a divorce. This also gave PACS vendors a bad reputation of wanting to "lock-in" customer data, and it has led to the evolution of small, very clever companies who specialize in cleansing data, standardizing private DICOM tags, etc. The specialist companies then migrate the DICOM from one vendor to another.
Dr. Neelam Dugar is a consultant radiologist at Doncaster Royal Infirmary, U.K., and chair of the Royal College of Radiologists' Imaging Informatics Group.From this has evolved the concept of a vendor-neutral archive (VNA), which essentially is an archive of DICOM data with standard tags and no proprietary compression, thus avoiding expensive migrations at the end of a contract. If customers keep their DICOM data as a backup in a VNA, they would have the freedom to migrate their data into the new vendor's PACS at the end of the contract.
The concept behind this type of VNA is largely based on data ownership and the freedom to move data at the end of contract. DICOM has also evolved as a standard. DICOM part 10 requires data to be held in vendor-neutral format to ensure data can be easily assimilated into any PACS vendor's archive, starting with the need to assimilate a small number of studies held in single CDs into a different vendor's PACS. This type of VNA includes a single data format: DICOM.
Today's PACS is a repository of radiology images. It stores and displays images from multiple radiology modalities from multiple vendors. Alongside this, the concept of an enterprise-wide clinical repository of medical images and documents, encompassing multiple departments outside radiology, has evolved. This, too, is being called a VNA. For any enterprise-wide archive/repository to work, there are three fundamental requirements:
- It must be able to receive images and documents from multiple sources/vendors.
- It must be able to store many data formats (not just DICOM), encapsulated PDF files, etc.
- It must be able to provide display of those images and documents by multivendor display systems.
To achieve the goal of multiple vendor source data storage and multiformat data storage, and to support multivendor display requirements, it has become increasingly clear that common standards must be adopted by enterprise archive repository vendors, data source vendors, and data display vendors. In the traditional PACS world, DICOM was sufficient as a ubiquitous standard. However, given the need to support storage of medical documents, DICOM is no longer considered to be ideal.
To support multivendor document image and document sources and multivendor displays, vendors of enterprise VNAs have realized the need to support the Cross-Enterprise Document Sharing (XDS) standard for indexing. This global standard has been widely adopted by major vendors.
As the remit of VNA evolves, it is also becoming clear that another standard called the Multiple Image Manager/Archive (MIMA) profile should be adopted by VNA vendors to deal with issues such as unique ID and accession number conflicts when data arrive from multiple sources.
VNA is an evolving concept, from customer ownership of DICOM data to an enterprise repository containing multiple data formats from multiple sources and supporting multivendor display. It has the potential to transform global healthcare IT. However, the transformation very much depends on the philosophy of VNA vendors and their willingness to adopt common vendor-neutral standards such as XDS and MIMA.
Dr. Neelam Dugar is consultant radiologist at Doncaster Royal Infirmary, U.K., and chair of the Royal College of Radiologists' Imaging Informatics Group.
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