BY GREG FREIHERR

Much faster scanning prompts manufacturers to seek ways to handle an increasing flow of information

Speed has become the most coveted characteristic for MRI and CT developers. Rapid data capture and processing are allowing both cross-sectional modalities to address clinical applications otherwise outside their scope. These technologies will only reach their potential, however, with advances in automation, interfaces, and image display, as the enormous quantity of data being delivered threatens to hinder rather than enhance productivity.

Exhibits at the RSNA meeting will reflect these technical challenges. Products will be present in abundance, but unlike past years will not be stars of the show. More highly featured will be clinical applications, particularly cardiac imaging and angiography, as vendors have concluded that, for now, it is new clinical capabilities that motivate prospective buyers.

Exhibit-goers will be deluged with information about coronary calcium scoring—an indicator of heart attack risk that Imatron pioneered with its electron-beam CT. The new generation of multislice CT scanners can deliver these measurements and much more. GE, Siemens, Picker, and Toshiba are grooming their multislice scanners to rival x-ray angiography, which is still the gold standard of cardiac imaging.

“Multislice could really open up cardiology as one of the key strategic directions for CT,” said John Sandstrom, Ph.D., director of strategic marketing and CT at Siemens Medical Systems. “There is a renewed interest in making sure that we drive applications further and faster.”

WHAT TO LOOK FOR

At this RSNA show, vendors will move beyond calcium plaques to demonstrate that CT can detect soft plaques as well. In other cardiac highlights, GE will demonstrate how its LightSpeed QX/i can record myocardial perfusion. And a stent planning package from GE will measure vessels to size stents before intervention. The key to these new capabilities is innovative techniques that deliver temporal resolution equivalent to what can be achieved with a 160-msec revolution.

“We might be able to get down even below that before we get to the RSNA,” said Ken Denison, manager of global CT for GE.

The technology that will produce these results is still a work in progress, although commercial shipments could begin next year, Denison said.

Cardiac imaging has not only eluded the grasp of CT until now, but it has also lacked the MRI one-stop shop approach. For the most part, cardiac packages released by vendors were the equivalent of today’s PC-based speech recognition tools: a novelty worth talking about but not worth using. At the RSNA meeting, vendors will present optimized MRI systems worthy of both.

The Siemens Sonata platform is a standout, offering a comprehensive cardiac examination that includes perfusion, morphologic, and ventricular studies. Brand-new at the Siemens booth will be a method for characterizing plaque, but Siemens’ postprocessing capabilities will likely make the greatest impression. The German company has groomed its Sonata to provide the staples of myocardial analysis—ejection fraction and myocardial thickness by heart region—while providing rapid three-dimensional reconstruction techniques, including fly-throughs.

“There will be a tremendous emphasis on postprocessing,” said John D. Pavlidis, MR division manager at Siemens. “We are determined to provide a comprehensive cardiac exam.”

Picker International will unveil contrast-enhanced MR angiography enhancements, including automatic bolus tracking software and a new stepping table. Both will be integrated with an interactive user-interface contrast injector control, as well as a new 12-channel phased-array peripheral MRA coil.

Picker’s flagship 1.5-tesla Eclipse will feature the new PD350 gradient system offering a 30 mtesla/m peak and 120 mtesla/m/sec slew rate. The new gradients should provide improved perfusion and diffusion imaging of the brain.

The ultimate expression of cardiac and brain imaging might be seen at very high field strength. GE will expand last year’s offerings at the RSNA meeting, showcasing its VH/i (very high field/interactive) MRI program. Other vendors will offer their own 3-tesla systems.

Siemens will showcase its dedicated 3-tesla brain scanner, the Magnetom Allegra, and announce a 3-tesla platform for whole-body imaging. Both systems are based on Magnetom Symphony components, including active shielding to minimize siting requirements.

Picker International plans to describe its program for developing 3-tesla systems in hopes of attracting clinical partners. The company’s purchase earlier this year of Surrey Medical Imaging Systems of Surrey, U.K, a premier manufacturer of very high field systems, should provide a market advantage. The plan is to add a standard 3-tesla system, probably optimized for neurologic and vascular imaging, to the Picker product line, which currently ranges from 0.23- to 1.5-tesla. Picker engineers are working on a prototype, although it probably will not be ready for the RSNA exhibit.

MULTISLICE PROGRESS

The multislice revolution, barely more than a year old, will come to fruition at this year’s meeting with GE, Siemens, Picker, and Toshiba America all showing scanners capable of generating four slices with each gantry rotation. Philips plans to release a premium product, the CT Vision Secura, that will be upgradable to multislice. The Secura will hit the market when the detector becomes available, possibly as early as next year. Having the basic platform allows engineers to concentrate on optimizing the specific components necessary for multislice imaging.

“We are working on the reconstruction and data management technology, the detector and image quality specifications,” said Janet Collins, Ph.D., North American business director for Philips CT.

The Holland-based company will introduce a mid-tier system called the CT Vision Aura at the RSNA meeting. This product will share the same functionality as Secura, but with a less powerful x-ray system and slower gantry rotation of one second, versus 0.7 second for the Secura.

Toshiba will be exhibiting its multislice detector for the first time this year. Each of the four detector rows in the center is 0.5 mm wide. The other 30 rows (15 on each side) are 1-mm wide. Regardless of the number of detector rows, however, the Toshiba detector delivers only four slices, just as its competitors do. The limiting factor is the data acquisition system (DAS), said Charles Corogenes, director of Toshiba’s CT business unit.

“If we ever get to the point where we have a DAS that’s cheap enough and fast enough to handle the data, we could have 32 slices with the present detector,” Corogenes said. “If we did it with today’s technology, (the scanner) would have to be huge and it would be very expensive.”

Toshiba will emphasize the practical side of multislice. The company plans to introduce a high-performance fluoroscopy package for the fully outfitted Aquillion.

“With multislice, you get a wider slab of data to look at,” Corogenes said. “That helps with needle orientation.”

With single-slice scanners, the needle tip easily moves beyond the plane being imaged. The ultimate solution is to expand data processing to offer 3-D reconstructions in real-time, he said.

Aquillion was released in fall 1998, but only in a single-slice configuration. The Japanese company hoped to sell the single-slice Aquillion on its mechanical prowess—the ability to do half-second rotations—and the promise of multislice to come. More than 20 units were sold to U.S. customers and are prospects for this upgrade, which will soon be available. Meanwhile, Aquillions configured with multislice technology have begun shipping. Toshiba will spotlight this system at the RSNA show, along with a companion product called Asteion.

The $200,000 price difference between the two systems is reflected in the Asteion’s less powerful generator and x-ray tube. (Toshiba declined to give a list price for either system, noting only that they would be competitive with similar products.) The big difference, however, is in rotation speed: three-quarters of a second for Asteion, and a half-second for Aquillion. Both can handle multislice scanning if outfitted with the right detector.

Siemens is developing a similar family for its customers. It will unveil two new CT scanners: the Emotion, featuring an 800-msec rotation, and Balance, a one-second rotation scanner. Both products feature advantages in siting, as the electronics that would have otherwise been put in cabinets are packed in the gantries, which themselves are thinner than in previous models. The helical products can be upgraded to the high-performance Somatom Plus and multislice.

GE will debut a new product, HiSpeed ZX/i, which will be plugged in below the premier LightSpeed, but features high-performance single-slice scanning at a competitive price point, according to the company. GE will also introduce a low-tier scanner for overseas markets and U.S. physicians’ offices. The price, around $200,000, is noteworthy for a helical scanner.

BETTER AND FASTER MRI

GE and Siemens will be brandishing the power of interactivity, much as they did at last year’s meeting when both focused on real-time imaging as the means to new clinical pathways. GE spokesperson Tom Beckman said only that the company would have “a lot of exciting things that we’ll be unveiling for the first time at the show.”

Siemens was more specific. It will unveil a neurofunctional imaging package that automatically corrects for patient motion in real-time. The new package fully automates both the acquisition and postprocessing of functional imaging, according to Pavlidis.

The computer figures in the orientation of the slice when determining how to handle errant data. If the motion could cause gross artifact, the computer rejects the data. If the motion is subtle, algorithms are triggered to compensate.

“You can see in real-time the evolution of data and how the system takes into account possible motion correction due to involuntary patient motion,” he said.

A key feature at the Philips booth will be a multi-array technology called Sense (sensitivity encoding). The work-in-progress uses several coils to simultaneously measure the same body region, correcting for aliasing effects and cutting measurement time dramatically, depending on the number of Sense coils employed. Five coils used in cardiac studies, for example, render a four-fold reduction in scan time. Early studies have produced real-time imaging sequences at 40 frames/second.

“Sense is very exciting because it will speed up imaging on all applications, not only cardiac, but neuro, angio, and abdominal imaging,” said Guido P. Stomp, Philips business unit director of MR marketing.

Toshiba America will introduce a new high-field product designed specifically for patient comfort. The 1.5-tesla Excelart Pianissimo features a compact magnet with a patient opening of 65.5 cm, the largest of any commercial system, according to Martin Forbes, director of MR sales and marketing. Additionally, system gradients offer up to 90% noise reduction compared to other high-field systems, he said.

“When we demonstrated this noise reduction to the market survey group, which comprised doctors, technologists, and administrators, 90% thought it would be a significant benefit to the patient and 80% thought it would give them a superior presence in their own markets,” Forbes said.

Toshiba’s earlier high-field system, the Visart, can be retrofitted to the Excelart configuration, he said. Older models, however, will require a magnet upgrade.

Toshiba is best known for its open superconducting system, Opart. New for the 0.35-tesla product will be a motorized table, an interface that allows operation at the tableside, an enhanced monitor, and coils that provide not only improved image quality but better access to the patient. One of the new coils, a work-in-progress designed for breast imaging, will work with a biopsy gun. Partly driving the development of these devices is interventional MRI, whose potential Forbes describes as huge but largely unrealized.

Interventional imaging will be a highlight for Picker’s open MR system, Outlook Proview, which will be outfitted with a basic package for MRI-guided procedures, including an in-room console and monitor, dedicated protocols for tracking biopsy needles in real time, and special coils. A second package, built around optical tracking technology, will include an infrared camera, as well as tools with integrated LED trackers.

“With this, we will always know where the tip of the needle is so we can automatically collect data at the tip of the needle,” said Mike Vitagliano, MR marketing manager.

One of the pioneers of open MRI and a major proponent of interventional applications, Hitachi Medical Systems America, will bolster the capability of its flagship Airis II system. The company will expand its product line of phased-array coils. One of the primary clinical targets will be orthopedic applications, particularly for the shoulder. But Hitachi’s most impressive works to be featured are still months from commercialization. These are echo-planar imaging (EPI), diffusion-weighted brain scanning made possible by EPI, fat-water separation, and contrast-enhanced MR angiography, all of which are currently seen primarily on high-field systems. Getting these techniques to run on a mid-field open system was not easy, said Sheldon Shaeffer, vice president and general manager of MRI at Hitachi.

“You need a high homogeneity magnet, high slew rate gradients, and a computer system fast enough to handle the data coming in,” he said. “So we had to optimize all the components of our MRI system.”