Short-bore magnets spur debate over future of open scanners

Dr. Peter Rothschild fulfilled expectations and proposed a bold vision in his remarks at the annual Open MRI conference in Las Vegas, May 13-16.

“Within the next three to five years, all new magnets being sold will be open,” Rothschild said. “And they’re going to range from 1.5 tesla on down. We’re going to switch from being both open and closed to being completely open.”

Such predictions are nothing new for Rothschild, medical director of Open MRI, a provider of outpatient imaging services with clinics in Kentucky and California. An outspoken proponent of open MRI, he was among the first to predict the current infatuation. But some manufacturers believe his vision of the future needs corrective lenses.

“In the future, I believe we will see more short-bore conventional MR systems,” said Mike Vitagliano, MRI marketing manager for Marconi Medical Systems.

Earlier this year, Marconi received FDA clearance to market its ultrashort, 1.4-meter Infinion 1.5-tesla closed magnet. Patients unwilling to enter open magnets have consented to be scanned on the new closed system, Vitagliano said.

“We talk with customers every day who are excited about the patient friendliness and openness of the Infinion,” he said.

The momentum maintained by open systems for several years has slowed. Unit sales in the U.S. have been dropping over the last few quarters, a trend that appears to be continuing in 2001. Orders for open field systems made up just 24% of the total unit orders placed in the fourth quarter of 2000. Just four years ago, sales of open MRI scanners were propelling the U.S. market to new heights, accounting for some 47% of all units sold in 1997.

The drop in low-field open sales in the U.S. is due at least in part to a saturation in this market segment and a slowdown in replacement sales. Hitachi Medical reports that replacements make up only about 25% of its sales of open units. Sheldon Schaffer, vice president and general manager for MRI at Hitachi Medical, believes many sites are putting off replacing their systems until they can figure out whether to buy another low-field product or one of the new higher field, open products.

“There are a lot of people looking forward to see what is going to happen in higher field open MRI,” Schaffer said. “And I think those questions will probably get answered in the first half of 2001.”

But the U.S. may not be typical of world markets. Open MRI sales are strong outside North America, according to Robert G. Gylling, vice president of MRI product strategies at Marconi Medical Systems.

“For us, 2000 was the best year ever (for low-field opens),” Gylling said. “There is a down trend in the U.S., but an up trend in the rest of the world.”

Open scanners will continue to be a major part of the marketplace, according to Phil Chang, MRI marketing manager for Hitachi Medical. But the focus will shift from a simple definition of systems as either open or closed to one that addresses the underlying appeal of open systems-patient comfort.

“Increasing accessibility for large and anxious patients and less noise are very much in the minds of developers, along with image quality,” Chang said.

Image quality, speed, and cutting-edge applications are the top priorities for engineers at Siemens Medical Solutions, said Anne Deery Sheehan, Siemens’ open MRI product manager.

“Patient comfort is a major consideration. However, we have never been willing to sacrifice image quality and applications leadership for an advertising advantage,” she said.

She added that the development of a 1.5-tesla open system represents a considerable challenge.

“It’s really a matter of cost. The more open the system, the larger the system dimensions and the larger the costs,” she said. “Will the market pay twice the price for a 1.5-tesla open system with essentially the same applications (that are available) on the current generation of short-bore systems?”

If Rothschild is correct that all new systems sold five years from now will be open, critical technological advances must be achieved. Several manufacturers already have or are developing systems operating at 1 tesla-and rumors abound of experiments with open designs up to 1.5 tesla.

“If you can break the 1-tesla barrier, you can easily go to 1.5 tesla,” Rothschild said. “Patients are demanding it.”

Clearly, the business model for centers featuring open scanners-appealing directly to patients-has succeeded. The introduction of open systems all but quenched any interest in closed mid-field products.

“It’s gratifying to see that virtually all the manufacturers today have come out with open magnets,” Rothschild said. “And they range up to 1 tesla. Other than field strength, there is no intrinsic advantage to a closed magnet.”

But a true vision of the future may not include closed, open, or even short-bore magnets. Dr. Mark Winkler, a professor of health science at the University of Nevada, Las Vegas, predicts that open and closed systems will eventually merge into an overall more patient-friendly style.

“You’re basically merging the open philosophy of patient friendliness with the closed philosophy of higher signal-to-noise,” he said.

Such a merger makes sense for one overriding reason: many centers currently use both open and closed systems. A design that incorporates the two would give patients the best of both worlds while sparing buyers the cost of purchasing and maintaining two systems that perform many applications with comparable success. What such a scanner will look like, however, is anything but certain.