f02a.jpg (13043 bytes)Lynn Carvel, a radiologist at Delta Medical Center in Memphis, Tenn., is helping an internal medicine doctor open a new office.

She has successfully convinced him that a digital X-ray unit is the right piece of equipment to install. A technologist will take the images of a patient, then transmit them digitally to Carvel at her home, where she will review the images on her 21-inch high-resolution monitor. She will be able to confer with the doctor and give a preliminary evaluation while the patient is still in the office. Although the image quality is excellent and Carvel feels comfortable diagnosing from home, legally she cannot unless she has a 2K monitor.

“It takes the liability off of him for interpreting the films himself,” she says. “None of this would be possible without teleradiology.”

Whether its purpose is long-distance consultation at a hospital or radiologist’s home, review by an on-staff radiologist at another hospital, making up for short staff or facilitating emergency treatment where local hospital systems may be destroyed or malfunctioning, teleradiology fills a vital role in radiology — providing access where radiology resources may be slim.

According to a 1999 report on telemedicine from market research firm Frost & Sullivan (Mountain View, Calif.), $108.8 million were generated in 1998 and systems and services sales growth will run about 16 percent through the next six years. If that forecast holds, the telemedicine market would reach $307.3 million in 2005.

The two factors that are most attracting medical professionals to telemedicine are the increase of high-quality video technologies and the affordability of videoconferencing equipment. The approximately 1,000 sites that use telemedicine are taking advantage of faster, inexpensive networks and new security measures available in teleradiology systems.

The Push and Pull
“Our customers range from radiology practices where there’s a single radiologist to very large customers where teleradiology is a method that they’re using to do primary diagnosis,” says Shelly Fisher, vice president of sales at Brit Systems Inc. (Dallas). The company designs products for PACS and teleradiology, writes connectivity software, provides viewing software and storage software for archives and Web servers, as well as provide storage services. The company’s systems begin at $15,000 and have run as high as $7 million. Delta Medical System’s Carvel is one user of Brit’s push-based system, the Radiology Workbench.

The Radiology Workbench uses a UNIX system that meets American College of Radiology guidelines for primary interpretation of images. It comes in 10-bit and 8-bit models, and can be equipped with a P1540 graphics card from Metheus (Beaverton, Ore.). Resolution ranges from 1280 x 1040 to 2048 x 2500. The company has another system called the Referral Workbench for post-interpretation reviews.

There are two basic modes of transmitting teleradiology images. A query/pull Web-based system allows the radiologist or other authorized personnel to look up a directory of available images and “pull” what he or she wants to review from that list. In a non-Web-based system, the exam site or other facility can “push” which images they want to go to a particular radiologist. “[The origin site is] in control of where and when the images are pushed, and to whom. That push mode is inherently more secure,” says Wayne DeJarnette, president of DeJarnette Research Systems Inc. (Towson, Md.), a maker of teleradiology systems. Pull-based systems have a greater risk of unauthorized users viewing images.

DeJarnette currently offers push-based technology, and is working on new technology that will allow the next generation to be either a push-based model or a Web-based query/pull model. Push-based systems also have more sophisticated viewing abilities on non-Web-based systems, says DeJarnette.

The two components in the DeJarnette system are the TeleShare IQ and the NetShare 1000. The TeleShare IQ is the site resident server, which has the ability to receive images from DICOM imaging modalities, study a series of images, store them on disk and then forward them. It can use any modem line (such as ISDN, T1 or POTS) and compress in lossless or lossy JPEG, or wavelet. The NetShare 1000 can interface with non-DICOM modalities and convert the images to DICOM.

The NetShare 1000 also offers the capability of route-by-route distribution, meaning that hospital administration can set up specific routes for different compression ratios or modalities. The user interface allows for destination routing, scheduling and scheduling rules as well. This is useful for when a radiologist works at several different hospitals and must be tracked so that images arrive where he or she will be for that day.

Images-on-Call (Dallas), is another vendor that builds complete teleradiology systems, from acquisition to home, in-office and hospital workstations. Its teleradiology products include a video capture digitizer station that collects images from video-based modalities and a film digitizer station that converts film to digital images. The systems are scaleable to grow with budget or size of a facility.

The latest module was introduced in December at the Radiological Society of North America (RSNA) meeting and is called a push socket module. It allows the hospital to push the images to the radiologist over faster Internet connections via DSC or cable modems where they are decompressed and available for review when the radiologist is ready.

This method is preferred by radiologists for efficiency’s sake, says Patrick Barr, M.D., director of research at Images-on-Call. Wavelet compression is used because it gives high image quality at a high compression ratio, and the company is currently on its third generation of enhancements to wavelets, according to Barr.

Clarity Counts
Generally, image quality in teleradiology depends on the type of file, the body part, and the speed at which it is sent over the network. “That’s going to determine how well you can compress something and keep it clinically lossless,” says DeJarnette.

Chest scans, for example, are easy to send with no loss of quality after decompression, while head CTs and head and spine MRs are more difficult. The hospital decides what its limits will be for compression to ensure accurate readings by the radiologist.

If the system is being used for primary diagnosis, Brit Systems recommends that customers limit their compression to 20:1. However, it is ultimately the decision of the individual doctor since the ACR doesn’t have any requirements for compression, according to Fisher.

“I think when you keep the compression to a reasonable amount, you don’t have real issues with image quality,” she says. Brit Systems uses JPEG for transmission because it is a standard and people are familiar with it, and the systems also conform to the DICOM standard, which eases transmission to other DICOM-compliant machines. Fisher believes getting transfer syntax between two companies that use JPEG to work together is important in telemedicine.

An additional factor to consider in teleradiology is the quality of the monitor. Brightness, contrast, dot pitch, distortion and image “blooming” should all be taken into account. The ACR recommends 1K view stations with 50 ftl of brightness if using the monitor for primary diagnosis. Typical teleradiology viewing stations run from $10,000 for landscape or portrait mode display to $25,000 for a specialty 2.5 lp/mm display.

Safe and Sound Via the ’Net
Before the Internet, image transmission was point-to-point, but now images are traveling over public lines, increasing the chances for a hacker to get into private medical records.

“One of the things that I’ve seen from healthcare professionals and CIOs is that they seem to be a pretty discouraged lot, in that there’s a tremendous amount of medical information out there in the clear already and they’re wondering whether one can ever secure this amount of information,” says Jeremy Wyant, senior technology specialist at CyberTrust, Needham Heights, Mass. “Most of the professionals I talk with understand what we’re doing and what we have to offer and believe that it will actually work. The next big hurdle is to find cost-effective ways to deliver this technology and integrate it with existing systems and merge it with other new technologies that are coming along in teleradiology.”

One of the major elements in determining the level of security necessary for a teleradiology system is the Health Insurance Portability and Accountability Act (HIPAA), specifically Section 45 CFR Part 142, a proposed rule that was designed to encourage development of a health information system. It also calls for the security of all patient-identifiable information and the authentication of people sending and receiving such information.

The goal of securing medical files is to make it extremely difficult to get into the system, if not impossible. This is achieved through several layers of security measures, generally firewalls, passwords, encryption, and authentication all the way to virtual private networks, PKI (public key infrastructure) and digital certificates.

Vendors such as Brit Systems can restrict access according to criteria that the hospital sets up or set up a private network. If necessary, they can achieve B1 security, a high level of security defined by the government. To meet HIPAA guidelines, they are working on better ways to track who has had access to certain patient files.

Images-on-Call restricts access to the system by using PKI technology. A hardware key must be present on the receiving machine to receive images and communicate with the sender, explains Barr. A list of authorized users is at the site where the images originate, and the site also logs all of the transmissions. Everything that passes between the two machines is encrypted with 128-bit encryption. The system also uses a technology called “knowledge of a shared secret,” where the transmitter issues a challenge to the receiving device that is not displayed on screen. It must be answered correctly in a given time frame for the transaction to continue.

CyberTrust creates secure environments for e-commerce transactions. The company has been building PKI systems for the government since the 1980s and then moved into commercial systems. Its core business is selling standards-based digital certificates used for identity technology to individuals, and providing outsource services for hospitals that want to give digital identities to physicians or patients, says Wyant. “When you’re talking about something like teleradiology, you’re talking about usually some fairly specialized, not off-the-shelf capabilities,” he says. Prices generally depend upon the number of certificates issued, the hosting services and the system components because they are custom designed for an individual facility’s needs.

With CyberTrust technology, a password is used to access a private key that is stored on a Smart Card, a credit card-sized device containing a computer chip. When inserted into the computer, the Smart Card identifies the user without being exposed on the PC, keeping it safe from viruses. Wyant says these two factors provide strong authentication for a user. Digital certificates are installed within the browser, making them difficult to share. They also have the ability to track transactions through a signed audit trail. This provides information on who has seen which files and when, providing non-repudiation (legal-binding proof that the person had access). The Smart Card also can be used in more than one computer, as long as the computer has a Smart Card Reader that plugs into the serial port (about $25) and a piece of driver software. When lost cards are reported to the company, the certificates are revoked. There are parameters to limit PIN guessing in case a lost card is not reported. The company also partners with enCommerce, Santa Clara, Calif., and Netegrity, Waltham, Mass., to provide fine-grained access to files that is limited based on content or role of the user.

“I think that [teleradiology is] going to be spurred on even more by accessibility to high-speed, low-cost networks,” says Brit’s Fisher. Of course, with these advances come more legal issues such as where readings will be done and what different states will require.

“Teleradiology is an accepted technology now, it has been for many, many years,” says Barr. “It’s basically considered a fundamental part of any radiology practice … It’s a crucial part of the imaging puzzle nowadays.”

For others, teleradiology is a potential money-maker. Carvel is interested in following the footsteps of physicians in northern Mississippi and Nashville, who are going around the country to smaller hospitals to contract their services for reading exams long distance. Teleradiology will not only save capital and human resources, but also improve the market for better healthcare while preserving a patient’s privacy. end.gif (810 bytes)