Siemens 1-tesla open system on track for mid-2001 shipment

Integration of magnet and components in progress

The pieces of Siemens' 1-tesla open MRI system are being put together this summer, as the still-unnamed scanner nears its scheduled product launch at the next RSNA meeting in November.

Siemens engineers in Germany are assembling components of the prototype system made by the Medical Engineering Group in Erlangen, with the 1-tesla magnet being furnished by Oxford Magnet Technology of Oxford, U.K.

"We integrate the magnet with all the hardware and then send the magnet back, if we want changes or modifications made to it," said Nancy Gillen, vice president of the Siemens MR division.

By the time the system is complete later this year, the back-and-forth process may have occurred several times, according to Gillen. Development is on track for product launch at the RSNA meeting, she said, with shipments starting six months later. The system will be formally named at the November meeting.

Siemens has signed up about 10 sites to receive the high-field open product when systems become available, according to Heinrich Kolem, Ph.D., vice president of Siemens marketing. These sites conduct routine patient exams rather than research, Kolem said.

A critical component of the system is the hybrid magnet, which comprises two superconducting poles—one on top, the other on the bottom—held in place by two iron supports. The proprietary technology is protected by patents, according to Gillen.

"But at the present time we can't discuss what some of those patents are," she said.

The vertical configuration of the magnet requires that consumption of the helium used as a cryogen be minimized, Kolem said. If the level of helium drops too low, the magnet could be damaged. To insure against problems, he said the system includes another cooling technique that design engineers recently optimized.

"The challenge was to make this system robust," Kolem said.

Oxford Magnet Technology, in which Siemens owns a 51% equity stake, is a supplier of magnets not only to Siemens but to other MRI manufacturers. This gives the company the opportunity to sell its 1-tesla magnet to vendors other than Siemens, Gillen confirmed.

"That's for the future to see," she said, "but the magnet is not the only thing that makes the product."

Other critical components, which emanate from Siemens, are the gradients and radio-frequency system, as well as the integrated panoramic array coils and the company's own front-end software. The greatest challenge is to get the pieces to work as a whole. Doing so, Gillen said, requires fine tuning.

"Obviously, we're trying to find the optimum configuration for the system and we'll make changes and improvements in the system until we get everything on the product that we set out to," she said.

The engineering priorities have been to tweak field homogeneity and improve gradient performance. The goal, Gillen said, is to have a system that is clinically valuable in its first release.

Ultimately, the product should be able to perform at the same level as a closed high-field system and conduct such advanced whole-body applications as spectral fat saturation, diffusion for stroke imaging, perfusion, MR angiography, and BOLD (blood oxygenation level-dependent) imaging. This level of performance, however, might not be possible until later versions of the system are released.

"There are certain technical challenges," she said. "There are field-of-view challenges and things of that type. But our product plans call for it to achieve the same performance as our Harmony 1-tesla scanner."

About 85% to 90% of patient procedures that can be done on Harmony should be possible on the first 1-tesla open system shipped, Kolem said. Within six months, the functional level of this open system should be the same as Harmony's.