A Look Inside IHE

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.

HL7 and DICOM integration happened slowly before IHE, according to Kevin O'Donnell, co-chair of IHE's radiology committee and manager of systems solutions at Toshiba. "You run into a lot of chicken-and-egg problems, where you have System A and System B and they don't work together - so whose problem is it?" he says. "IHE has been very good in radiology [in breaking] that deadlock by bringing both sides to the table. Both sides see that the other side is willing to work."

Every system installation was an on-site custom installation before IHE, says David Channin, M.D., chief of imaging informatics at Northwestern Memorial Hospital in Chicago and a member of RSNA's electronic communications committee. But when vendors conform to IHE standards, buying new imaging equipment is much easier. "IHE allows the products to move more towards plug and play," says Channin.

Unfortunately, not all vendors have accepted IHE at the same pace, according to industry consultant Jim Maughan of Maughan Consulting. "In the early going, there was only marginal involvement from RIS vendors," he explains. "Now all the players are involved and we're on the brink of tangible benefits in terms of interoperability."

Carr estimates that about 90 percent of the industry's vendors are active IHE participants. "Adherence to the IHE technology framework is very strong in some areas and growing in others," says Carr. "Among the modalities, workstations, printers and PACS, it's very strong. With RIS, it's getting stronger."

However, Carr admits that IHE has "a ways to go" with information systems vendors. Maughan explains, "The HIS/RIS guys were thinking they had it under control. They didn't think they had to have standards."

And their reserve toward IHE has resulted in long cycles of on-site product integration work for healthcare facilities. "Getting our RIS vendor on board has been less than satisfactory," says Gary Wendt, M.D., M.B.A., director of informatics at University of Wisconsin-Madison and director of enterprise integration at the UW Health system. "It would be nice if they would be proactive, not reactive."

On the other hand, UW-Madison's experience with PACS and modality vendors has been positive. Wendt cites the work his vendors have done to meet the requirements of the Presentation of Group Procedures (PGP) integration profile, which enables management of cases where images for multiple procedures are acquired in a single acquisition step. "For example, with spiral CT, it's totally feasible to scan from head to toe in two minutes and have 4,000 images," he says. "The neurosurgeon doesn't want to open all the images to find the ones of the head that he wants."

UW-Madison's PACS vendor and CT modality vendor have been working together to implement PGP, which would enable physicians to isolate necessary data from a large data set. "[The vendors] see it's a problem and [there's] not an easy solution," says Wendt. "Both vendors have looked at [the IHE PGP integration profile] and know it will require a ton of work but they know it will benefit them to work it out."


IHE's biggest challenge is end-user awareness. Although it has taken some time for word about integration profiles to filter down to the end-user, Carr says that IHE's education efforts are beginning to pay off. "More and more we're seeing user involvement and IHE is showing up in customer RFPs," he adds.

Northwestern's Channin is a good example - he inserted a clause in Northwestern's imaging RFPs that requires all vendors to meet the appropriate IHE integration profiles. "They have to support all IHE transactions [in which their product] plays a role," he says. "They may not have the capability at the time but they have to commit to getting there."

But too many end-users don't know about IHE and don't take advantage of its benefits, argues Paul Nagy, Ph.D., director of the radiology informatics lab at the Medical College of Wisconsin and a member of the IHE users group. Nagy believes the problem is related to the maturity of PACS technology. "PACS has about a five year lifetime, RIS has maybe 10 years," he says. A facility will likely have problems if they want to switch PACS vendors and the equipment doesn't meet IHE specifications-but they don't think about that when they're buying the original system, he adds. "[Customers will] realize they're locked in and can't change vendors," Nagy says. "They'll have no pull in making the vendors do what they want."

With only 15 to 25 percent adoption rate in North America, a lot of healthcare facilities haven't even migrated to their first PACS - much less their second. Nagy believes the importance of IHE will become more evident to many end-users when they're buying their second PACS, and predicts that IHE will gain more adherents on the customer side as PACS technology matures. "RSNA tells customers they should buy products that support IHE, but sometimes they have to make their own mistakes before they actually pay attention," he says. "It's a bit like trying to pass on wisdom to your children or grandchildren."

End-users in the position of making purchasing decisions should use IHE profiles as a purchasing tool, says RSNA's Carr. When evaluating vendors for an RFP, Carr recommends reading the IHE integration profiles that relate to the related product functions. Then, look for the vendor's integration statement of IHE conformance. Most of the vendors that have met IHE requirements for a specific profile publish their integration statement on their website. Carr encourages end-users to add a requirement for meeting IHE integration profiles in their RFPs.

Nagy concurs. "Unless you want to hand your checkbook to your vendor, make sure they adhere to open standards," advises Nagy. "The best opportunity to make an impact on a vendor is before you make a purchasing decision, not after."

IHE Moving Beyond Radiology

In the enterprise that is healthcare today, radiology integration issues increasingly are becoming relevant to other healthcare domains. For example, data management issues such as patient record location and enterprise user authentication are shared by multiple clinical environments. And a variety of critical issues in RIS integration relate to the implementation of the electronic medical record (EMR) - considered by many to be the "holy grail" of healthcare information management.

Recognizing this, IHE leadership created the IT infrastructure domain to deal with issues that arise from sharing information across departmental and institutional boundaries. "[The IT infrastructure domain] is where we deal with the HIS and enterprise and inter-enterprise issues of sharing healthcare information," says Glen Marshall, the co-chair of IHE's infrastructure planning committee and advisory systems designer at Siemens Medical Solutions.

During 2003, its first year, IHE's IT Infrastructure committee oversaw the creation of five integration profiles. The first Connectathon for IT Infrastructure will be held in February at the HIMSS exhibition in Orlando.

And IHE's expansion efforts are expanding beyond the IT infrastructure domain. In 2003, the American College of Cardiology (ACC) took on the leadership role in bringing IHE to the cardiology domain. Initially, IHE will be identifying similarities and differences between cardiology and radiology workflow and determining if any IHE radiology findings can be applied to cardiology.

IHE is also ramping up efforts in the laboratory and pharmacy domains. However, its work in imaging will continue - upcoming issues for next year include how to address shared removable media such as CDs and DVDs.