A Look Inside IHE

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As the implementation of picture archiving and communications systems (PACS) moves from early adopters to mainstream users, the healthcare industry is learning to manage the connectivity issues between PACS and its more established counterparts - modality input devices and radiology information systems (RIS).

A great deal of work has been accomplished in this area by the Radiological Society of North America (RSNA) and the Healthcare Information and Management Systems Society (HIMSS), who jointly formed Integrating the Healthcare Enterprise (IHE) to alleviate system connectivity issues between the differing digital imaging technologies. Six years after IHE's creation, Health Imaging & IT takes a look at how IHE works and examines its accomplishments.


As PACS technology has matured and made digital imaging a realistic replacement for film, industry leaders became worried by the lack of a common language between PACS, RIS and hospital information systems (HIS). PACS is based on the Digital Imaging and Communication in Medicine (DICOM) standard, while HIS/RIS rely on the Health Level 7 (HL7) standard. Accurate and efficient information exchange between the two technologies is hampered by their reliance on different standards, their use of separate databases to store their respective data, and a multitude of technology suppliers whose natural tendency is to provide proprietary technology that locks customers into their solutions.

RSNA and HIMSS decided to address this issue by forming IHE in 1997. They invited medical administrators, IT professionals, vendors and members of the existing standards bodies to collaborate on standards-based blueprints that can be used to develop products that interoperate with those from other vendors. Initially focusing on the radiology domain, IHE's goal was to help healthcare facilities improve workflow, reduce implementation costs, and increase clinical efficiency. (See "IHE Moving Beyond Radiology.")

Through a process that involves regular committee meetings and product testing, IHE participants identify integration problems between DICOM and HL7. Under the supervision of RSNA and HIMSS committees, vendors with DICOM products and those with HL7 products work together to develop solutions to these problems. "It's a surprisingly cooperative vendor environment," says Christopher Carr, RSNA's director of informatics. "You might expect vendors to play to their vested interest, but they're interested in making customer problems go away."

Once a solution to a particular integration problem is agreed on and tested, IHE publishes an "integration profile," which strictly defines how DICOM and HL7 should be applied to specific actions related to the problem. For example, the Scheduled Workflow integration profile defines how the standards should be implemented to achieve the key steps in a typical patient imaging encounter - registration, ordering, scheduling, acquisition, distribution and storage.

Vendors then use IHE integration profiles to develop product interoperability. They can even test their products with multiple systems in an optional process called a Connectathon, a once-a-year event that's usually held in the parking garage of RSNA's Chicago headquarters. (Participants are advised to dress in layers.) The most recent Connectathon was held in October 2003 and drew in 35 vendors.

Once vendors have proven to IHE that their products meet the requirements of a certain integration profile, they publish statements of conformance known as "vendor integration statements." The value of IHE to end-users comes in the purchasing process. When end-users are sending out request for proposals (RFPs), they can reference IHE integration profiles and vendor integration statements to evaluate vendor product offerings and develop minimum requirements for vendors. Customers can be sure that products that conform to IHE integration profiles will be interoperable with other IHE compliant products.


Since it was formed, IHE has approved 12 radiology integration profiles (see example below). Dozens of products that support the various IHE integration profiles are available from a variety of vendors. RSNA's IHE website includes links to vendor integration statements from most of the major vendors, including Agfa Healthcare, Cerner Corp., Eastman Kodak Co., Fujifilm Medical Systems, GE Medical Systems, Philips Medical Systems, Siemens Medical Solutions and Toshiba Medical Systems.