The typical PACS includes its own long-term archive subsystem. While the all-inclusive package will present few if any data compatibility issues with its own components, there may be serious problems when the time comes to exchange data with other systems. The archive that it totally owned by the PACS application is usually only marginally DICOM-conformant. The assumption of the self-contained PACS is that there is very little sharing of study data with other systems. The PACS may respond to a remote DICOM query with minimal data, i.e. the original image pixel data and little else. Presentation States, Key Image Notes, and other key meta data objects associated with the images and created by the radiologist during interpretation may not be forwarded, because the PACS doesn’t treat these as DICOM objects, or it places them in Private Tags, or it uses a proprietary Value Representation (in the tag) to encode the information. Self-contained Radiology PACS are typically very stingy when it comes time to give up their data in a data migration process. The vendors really think of it as their data, and now that the radiology department has decided to leave them for another PACS vendor, the jilted vendor may be reluctant to help in the retrieval and migration of all of the data that really belongs to the health system. This translates to expensive and time consuming data migrations. Study the Archive’s DICOM Conformance statement very carefully. Anything less than full conformance for all data objects and SOP Classes should be addressed in the Contract. Build a technically sound, workable exit strategy in advance.
