Hitachi hopes to jumpstart demand for open MR

Hitachi Medical Systems America created the market for open MR almost single-handedly in the mid-1990s. This market segment, which in its heyday accounted for about 40% of new MR sales in the U.S., has all but vanished, leaving a trickle of demand.

Hitachi hopes to reinvigorate this market with its latest development, a 1.2T superconducting MR scanner, Oasis. The vertical-field system, formally released at RSNA 2007, is scheduled to begin shipping in April 2008. But Hitachi is already taking orders--and not from just any one segment of the installed base, according to Sheldon I. Shaffer, vice president and general manager for Hitachi MR and CT.

"We are seeing a lot of interest from a variety of institutions, large and small," Schaffer said.

Carrying a list price of about $1.5 million, Oasis is within reach of any facility considering a high-field scanner. It has the added appeal, Schaffer said, of offering an extraordinarily open experience for the patient.

Hitachi achieves this by offsetting the two poles that support the dual disks of the superconducting magnet. As the patient slides headfirst between the disks, which are completely open in front and back, the pole coming into view on the right passes by before the pole on the left appears. This ensures that the patient always has an unobstructed view on one side.

Oasis was shown at RSNA 2006 as a work-in-progress. It cleared the FDA in September.

Built around a gradient system with 33 mT/m amplitude and 100 T/m/sec slew rate, the scanner features Zenith receiver coils, the culmination of 20 years' experience in the development of vertical-field MR. This engineering track record is the strength of the open MR scanner, according to Schaffer.

But Hitachi Medical also drew from its sister companies to create the magnet, he said, and the active shielding to contain the vertical magnetic fringe field within the space typically occupied by a 1.5T field. Field uniformity is driven by the company's proprietary Higher-Order Active Shim Technology (HOAST), which is designed to ensure fat saturation over the scanner's 45-cm field-of-view.

In developing the high-field open system, company engineers migrated technologies developed for the Hitachi 1.5T Echelon, a closed cylindrical high-field scanner also in the company's MR portfolio. Among the shared technologies are many of the electronics built into 1.5T as well as the software.

Because the two systems have so many components in common, the latest developments for the Echelon are immediately compatible with the Oasis system. Tigre, a newly launched pulse sequence for the Echelon to support dynamic abdominal and bilateral breast studies, is also available on the Oasis along with Tigre Vasc, a noncontrast MRA protocol for visualizing the peripheral vasculature. Other Echelon capabilities built into Oasis include Rapid parallel imaging, Traq time-resolved MR angiography, and Radar patient-motion compensating technology.

Declining demand for open scanners, compounded by improvements at 1.5T and 3T, has led most vendors over the past few years to put R&D dollars into cylindrical systems. Toshiba America Medical Systems, whose early success in MR was based on a superconducting midfield open scanner, has stopped making the product, focusing instead on 1.5T systems. Several years ago, Siemens Medical Solutions abandoned plans to produce a 1T open MR in favor of a wide-bore 1.5T scanner. Only Philips Medical Systems has persisted and has developed its open 1T Panorama.

This dearth of innovation in open MR has created a pent-up demand that Schaffer hopes to satisfy with Oasis. He expects demand to come from the company's traditional customer base, privately owned imaging centers, despite reimbursement cutbacks due to the Deficit Reduction Act.

"Oasis will help them position themselves in the marketplace," he said.

Hospitals will also be attracted to Oasis, as some establish outpatient imaging centers and others round out their 1.5T or 3T holdings with another high-field scanner that differentiates them from their competitors, he said.