Siemens courts open MR customers with ultracompact 1.5T scanner

Siemens hopes to jump the gap between open and closed MR systems with the release on July 29 of an ultracompact wide-bore cylindrical scanner. Whether the company lands on its feet will depend on the open-mindedness of its customers.

The German giant is framing its new scanner, the Magnetom Espree, as the world's first open-bore MR scanner-a cylindrical system with an opening akin to those found on CT scanners. The bore measures 70 cm (2.3 feet) in diameter and offers 30 cm of headroom from patient nose to scanner bore ceiling. It is also extraordinarily compact, measuring just 125 cm wide, about 4 feet, allowing for more than 60% of exams to be completed with the patient's head outside the bore.

"We are talking about CT-like comfort for a patient going into a 1.5T scanner," said Nancy Gillen, vice president of Siemens' MR division. "We don't know of any patients who have refused a CT scan (because it was too closed)."

The company is framing the system as a new class of MR scanner: an open-bore category unlike any previously seen. But Siemens itself has been successful at accomplishing openness with another high-field product. Its flagship Avanto, a premium-performance 1.5T scanner released at the RSNA meeting last year, sports a 60-cm-wide bore, just 10 cm smaller than the Espree. Philips' Achieva also has a bore diameter of 60 cm.

Similarly, Espree, with its 125-cm girth, has the thinnest profile on the market, but other scanners are almost as compact. Philips developed the idea of compact MR magnets more than a decade ago, starting a trend that all manufacturers have followed. The company's latest, its premium-performance Intera Achieva, which was introduced at the 2003 RSNA meeting, has a width of 157 cm. Siemens' Avanto measures 150 cm wide, just 25 cm larger than Espree. And Toshiba's 1.5T Vantage is just 140 cm wide. Siemens' Allegro, a dedicated 3T brain scanner, has a width of just 130 cm, 5 cm wider than Espree.

While the question of whether Espree constitutes a new category with its open bore might be debated, there is no argument that the Espree is roomier yet more compact than any other MR scanner on the market. Its small footprint makes for easy siting, and the system is light enough to place on an upper floor, according to Gillen. But its compactness and openness come with a price. The field-of-view is more limited than that of premium performance 1.5T scanners, and there are "challenges" in field homogeneity.

These are largely offset by the integration of Siemens' Total Imaging Matrix. TIM, which was introduced at the last RSNA meeting along with the Avanto, makes up for what was traded off to make the magnet more compact. It brings back the signal to noise, Gillen said.

"TIM technology allows you to apply a radio-frequency technology (to overcome the lower gradients of the Espree) and patient moving technology (to overcome the narrow field-of-view)," she said. "This allows you to acquire images from different segments of the body by moving the patient through the magnet."

With the integrated whole-body surface coil system, Espree generates four times the signal-to-noise ratio of 0.7T and 0.6T open MR scanners, Gillen said.

Its sticker price is a welcome surprise, as it comes in at the lower end of the 1.5T range: between $1.5 million and $1.6 million. This is about $300,000 to $350,000 less than the Avanto.

Siemens is targeting the entrepreneurial segment of the market, composed of freestanding outpatient clinics. These facilities tend to cater to patient demands. The Espree might also find a home in hospitals as a second or third MR system for patients not suited to conventional cylindrical designs.

The industry has hinted for years that increasingly compact magnets may render clam-shaped open scanners obsolete. Siemens is now making that claim vociferously.

"To make a vertical high-field magnet is expensive, and the siting costs are prohibitive," Gillen said. "But if we make a 1.5T system with a short and open bore, we give customers what they are asking for, and they can achieve the throughput they need."

Efforts by Siemens and Philips to develop truly open 1T systems were technical successes, as each produced working configurations. But neither company could make its designs practical. Siemens went so far as to install its clam-shaped 1T Rhapsody scanners at four clinical sites, but siting costs were simply too high, according to Gillen. With the introduction of Espree, the company has confirmed that its program to develop a commercial 1T open scanner is over.

The Espree will not compete for sales against the company's other 1.5T scanners, said Gillen, who likened Siemens' product portfolio to those of car manufacturers. Each product is engineered to meet the specific needs of a type of buyer. Siemens' Avanto appeals to hospitals that want to perform the most advanced exams, from cardiac imaging and coronary angiography to diffusion tensor imaging.

Siemens' Symphony, only recently eclipsed by the Avanto, was the company's standard bearer for several years and remains capable of premium performance. (The company also makes a 1.5T Sonata, but this product is sold only outside the U.S.)

Espree can handle advanced cases commonly encountered in routine practice, including MR angiography, diffusion, functional imaging, breast imaging, whole-body scanning, and spectroscopy. Its appeal, however, is found in its physical construction. Obese patients will fit more easily into the wide open magnet. People afraid of tight spaces, as well as elderly patients and children, should also feel more at ease undergoing an exam in the Espree, according to Gillen.

"The Espree will not compete with the Avanto or Symphony," she said. "They are designed for different customers."

Work on the Espree began three years ago, after Siemens engineers were grappling with the formidable problems of building a 1T open. Company analysts recognized that demand for higher field open scanners was not materializing, while the purchase of midfield opens appeared to bottom out or even shrink slightly.

"We figured we'd better start looking at something else," Gillen said.

Details about the new system were closely guarded. Siemens executives referred to a high-field open system earlier this year in the context of questions posed by SCAN regarding its development of a 1T open. Information that the new scanner, then believed to be an open system with a 1T field strength, would be released at the end of July was previously published (SCAN 7/16/04).

As this issue was going to press, Siemens was planning to kick off a nationwide marketing campaign, targeting 16 cites through mid-October. The unveiling was scheduled for July 29 in New York City.

The first system will be installed Sept. 1 at the Mayo Clinic in Jacksonville, FL. Another U.S. site will take delivery the next month. Two more will be completed by year end in the U.S., and another overseas. The Espree will be in full production in February 2005.

The scanner will be available in only one configuration, featuring 33 mT/m gradients with a slew rate of 100 T/m/s (tesla per meter per second). With TIM boosting image quality and productivity, Espree is the company's answer to a quandary that has beset the industry since the mid-1990s: the need to address patient comfort yet provide productivity and image quality to the customer with a good return on investment.