IHE standard topples imaging's Tower of Babel

Vendors installing program that seamlessly links DICOM and HL7 on new equipment

BY KEITH DREYER, D.O., PH.D.

DR. DREYER is vice chairman of radiology at Massachusetts General hospital and chairman of the IHE 2000 Symposium, which will be held during the RSNA meeting.

Any institution considering the purchase of computed radiography (CR) or digital radiography (DR) equipment should insist that the device be IHE (Integrating the Healthcare Environment)-compliant. That will save time and headaches by guaranteeing that the equipment will be able to communicate with other hospital information systems. Without IHE, a radiology imaging device could be stranded and unable to send its information electronically to other systems. It would be impossible to integrate digital radiology images with other patient information.

Most hospital information systems use a communications protocol called Health Level 7 to connect different machines and equipment. HL7 allows the machines to talk to each another and exchange text data, including registration and discharge information, lab results, and reports. But HL7 was not designed to handle image data. In the 1980s, industry and professional groups created a new protocol, Digital Imaging Communications in Medicine (DICOM), to handle images. But HL7 and DICOM, which grew out of different roots, could not communicate directly. Without the definition of further standards, digital modalities could not send image data to HL7 devices, or even to text-based reporting and scheduling systems within radiology.

Third parties developed translation software that allows HL7 and DICOM devices to communicate with each other, but that approach created headaches of its own. An extra layer of software can affect system performance, and third party vendors may not stay in business or may fail to upgrade programs to keep up with HL7 and DICOM evolution.

It was IHE that came to the rescue. This protocol eliminates the need for middleware to translate between HL7 and DICOM and enables manufacturers to build the necessary links right in their original equipment. Thus programmed, DICOM machines will simply know how to talk with HL7 systems. No translation software will be required, and as the protocols change, IHE guarantees that machines will remain compatible.

The heroes of this story, the RSNA and the Healthcare Information Management Systems Society (HIMSS), created IHE as a joint effort. Using a common framework, IHE employs existing protocols to connect radiology imaging devices with other information systems in the hospital. It is supported by all the key industry players, including equipment manufacturers, standards groups, academic institutions, and CIOs. At the grass-roots level, it is organized and driven by representatives of hospitals (HIMSS) and physicians (RSNA).

Remember, no new software is required for IHE. The technical documents simply spell out how the protocols should communicate and how to map data fields from one system to the other. Vendors implement the standards on their own, as part of the software shipped with their devices. As IHE evolves, vendors are committed to supply upgrades. IHE will work out problems and discrepancies directly with the various standards groups involved.

HORIZONTAL INTEGRATION

IHE is a work in progress, but the goal is to enable clinicians to view, on their desktop PCs, all the relevant data for a single patient, including diagnostic images and the accompanying reports. There are also many other benefits to a fully integrated information system, including speed, reduced staff for moving information, fewer errors, and increased security.

IHE development so far has focused on setting technical standards for vertical integration, connecting machines within radiology, including each radiology imaging device and the text-based scheduling and reporting systems. Later, the IHE framework will support horizontal integration, allowing diagnostic images to be shared with systems outside radiology. The first step in this process, setting technical standards, has been completed, making it possible to purchase CR and DR systems that are IHE-compliant.

The initial IHE framework already offers important functions that reduce errors and improve service. For example, when an HL7-based radiology administrative system that registers patients and schedules exams cannot communicate directly with the CR or DR devices, a technologist must manually enter the patient's ID number and exam accession number into the modality directly. Studies show that technologists make data entry errors 20% to 30% of the time. If an error of just a single digit is made in either number, the test could get lost in the system, having no connection to a particular patient or order. Eventually the error may be found and corrected or the patient will be retested, but at additional cost.

IHE-compliant devices solve this problem. They talk with HL7 systems, using a feature called modality work list manager, and transmit the list of scheduled patients directly to CR or DR machine. The technician reads the work list directly on the CR/DR console monitor. The patient's ID number and test accession number are already in the machine and connected with the test about to be performed, reducing errors. Security is also enhanced, because fewer people handle the data. Another function, the perform procedure step manager, keeps track of the test in progress and notes when the test has been completed and stored.

CLOSING THE LOOP

The next objective for IHE is to complete the loop by creating a technical format to inform the hospital information system that a test is completed and that the rest of the workflow can begin. IHE will also make the images and reports available to other hospital information systems and to systems outside the hospital, and it will give radiology access to nonradiology data. This level also includes a method to reconcile patient identification errors, send monitor setting/adjustment information with each image to improve image consistency between workstations, and permit sophisticated report management and data entry tools such as voice recognition.

IHE works now, and will be demonstrated this fall at the annual IHE symposium held in conjunction with the RSNA meeting. The three-day symposium will offer a variety of panel sessions, demonstrating standards now in place involving multiple vendors and multiple devices in a simulated healthcare environment.

Since IHE is organized and driven by organizations representing buyers, it strives to ensure simple, reliable connections between CR and DR machines, as well as other radiological systems and devices. A fragmented and inconsistent standard for exchanging data creates headaches for everyone and can add burdens to IS departments and limit choices in purchasing new equipment. IHE compliance is a guarantee of compatibility, so it behooves everyone in the medical communication chain to insist on it from equipment vendors.