Open high-field scanners highlight wide range of new offerings in MRI

MRI has entered a renaissance, spurred by technological progress and customer demand that drove 1999 sales close to the $1 billion mark for the second straight year. The RSNA exhibit floor teemed with new systems as some manufacturers sought to leapfrog competitors while others hoped to expand their installed bases.

Most of the action took place in the high-field realm. Indicative of MRI’s future was the first wave of open systems above 0.5 tesla. GE, Siemens, and Fonar all hoped these early offerings would be judged on their potential value rather than their current shortcomings.

Recognizing that patient comfort was the force behind open system sales, Toshiba put a new twist on the issue with a high-field system that mutes the unnerving noises that accompany MRI exams. Philips introduced a new family of MRI scanners that accentuates the compact, flared magnets of the Gyroscan NT series while adding increased functionality. In a bid to broaden its appeal beyond open mid-field scanners, Hitachi unveiled a high-field, value-oriented system that emphasizes economy and clinical function.

Fonar

• Pre-RSNA hype focused on a seven-member product line. But of these, only the Echo was both new and commercially available. The 0.35-tesla unit, designed to sell in economically disadvantaged world markets, is essentially a scaled-down version of the company’s flagship Quad 12000, a four-post open system built around resistive magnets. Echo features a 16-inch gap, compared to a 19-inch gap on the Quad 12000. Echo is designed to support most standard sequences other than MR angiography.
• Fonar also debuted Pinnacle, a high-field superconducting open system, with an operating field of 0.6 tesla. In 2000, Fonar engineers will work to increase field strength to 0.8 tesla or more, which would meet the commonly accepted definition of a high-field system. Production could begin by the end of the year, according to the company.

GE Medical Systems

• The big story for GE was Signa OpenSpeed. The company’s high-field open system, unveiled Nov. 17 (SCAN 11/24/99), made a splashy RSNA appearance. The 0.7-tesla scanner strained the common definition of high field, classically defined as between 1 and 1.5 tesla. But GE executives rationalized their designation by noting the improved signal-to-noise ratio possible with vertical field systems, such as open MRIs, and equating the system’s images to those obtained from a typical high-field scanner. OpenSpeed, which should begin shipping in the second quarter, will support most routine MRI studies.
• GE also showed an experimental system incorporating a body gradient and a smaller, supplementary gradient designed to cover a field-of-view such as might be involved in a cardiac or brain study. The basic technology appeared initially as the Elscint Prima 1TG, which featured twin gradients that allowed users to choose between two slew rates during a single scan. GE has solved some of the technical problems encountered by the Prima 1TG; for example, those relating to off-center imaging in shoulder scanning.
• Probe 2000 is the latest version of GE’s spectroscopy device for the 1- and 1.5-tesla products. Scanning has been automated to correlate spectral and visual data. The process, which can be completed in five to 15 minutes, may require only a quarter of the time needed for spectroscopy on Probe/SVQ, GE’s previous spectroscopy package.
• An iterative step forward from interactivity technology is iDrive, a software package that allows the operator to zero in on lesions or other targets.
• New gradients were released for the 1- and 1.5-tesla scanners: Smart Speed, with an amplitude/slew rate of 23/50; HiSpeed Plus, at 33/77; EchoSpeed Plus, at 33/120; and CV/i (cardiovascular), VH/i (very high), and NV/i (neurovascular) at 50/150.
• A mobile version of Signa CV/i, the 1.5-tesla MRI scanner optimized for cardiovascular imaging, was highlighted. Three vendors of transports are equipped to house the scanner: Calumet Coach and AK Associates, both of Chicago, and Ellis & Watts of Cincinnati.

Hitachi Medical Systems America

• As demand for open mid-field systems begins to ebb, Hitachi is seeking to expand into conventional high-field with Celeris. The 1.5-tesla successor to Stratis II features phased-array coils and EPI capability. Celeris allows perfusion and diffusion imaging. The system will be commercially released in the summer, pending FDA clearance. Its design was accomplished collaboratively by Hitachi and Boulder-based Colorado MedTech.
• Airis II, the company’s flagship mid-field open product, was upgraded with multishot EPI and diffusion-weighted imaging, both pending FDA clearance. New coils include a phased-array shoulder coil, cleared by the FDA, and a phased-array spine coil, which is pending FDA review.

Lunar/Esaote

• Upgrading of extremity scanner Artoscan M continued with release 5.5. Key features include a prezoom capability, which fits the image to the window; a window link function, whereby images from different acquisitions can be compared; and mouse-controlled lookup tables to improve window and leveling.
• The ProScan upgrade assists patient positioning through the use of real-time scout images. Protocols have been restructured to match anatomical regions. Pulse sequences have been optimized to enhance image quality for each of these regions.
• The Enhanced Network Plus package converts images from a proprietary format into DICOM 3.0 on the fly, as they are transmitted over a local area or wide area network.

Marconi Medical Systems

• Productivity and expanded clinical capability remained a central theme at the company formerly known as Picker International. Upgrades of its Via technology included proton spectroscopy outfitted with water and fat suppression methods for scanning the head, as well as the breast and prostate. Acquisition and processing procedures have been automated to reduce the potential for operator error and to minimize exam time. The interface allows expert users to take direct control.
• New gradients, called PD 350, were released for Marconi’s flagship 1.5-tesla Eclipse. The PD (formerly PowerDrive) 350 offers a 30 mtesla/m/sec peak and a 120 mtesla/m/msec slew rate, promising improved perfusion and diffusion imaging of the brain.
• iPass automates exams using contrast agents for abdominal, peripheral, and carotid MR angiography. A real-time graphical interface helps determine test bolus arrival, as well as arterial and venous separation.
• A new bilateral, 12-channel quadrature coil was developed for imaging the abdomen and peripheral vasculature. The coil covers renal to medial plantar arteries.
• Preparing for the future of MRI intervention, Marconi focused attention on a 36-inch pedestal-mounted monitor for its 0.23-tesla Outlook ProView. In conjunction with a needle tracking system designed around optical sensors, the monitor provides guidance from needle insertion to the target.

Medison

• Development efforts continue on both the 1- and 3-tesla Magnum scanners. Engineers are evolving the 3-tesla system into a whole-body scanner, which at present is configured only with a head coil. Efforts are focused on the development of functional MRI and spectroscopy.
• The 1-tesla, short-bore scanner featuring a 55-cm patient aperture can support most routine exams. More than 20 have been installed in Korea. Another three are about to be installed at sites in Indonesia and Eastern Europe.

Philips Medical Systems

• Gyroscan Intera carries on the company’s efforts in high-field, compact, cylindrical scanners. Full production of the new family of scanners, with magnets operating at 1.5, 1, and 0.5 tesla, is scheduled to begin in mid-2000. The company plans to continue selling NT scanners, which are upgradable to Intera, through the first quarter.
• Explorer is a work-in-progress gradient at the super-premium end (amplitude 60, slew rate 150).
• Intera CV is optimized for the assessment of cardiovascular disease, featuring performance for rapid acquisition of data. MotionTrak technology corrects for motion artifacts resulting from respiration.
• Intera I/T (interventional therapy), an experimental configuration pending FDA clearance, has been optimized for interventional applications. A ceiling-mounted 20-inch LCD monitor, with an integrated keyboard and trackball, can serve as a virtual console in the scan room. The scanner is designed for complex procedures such as image-guided surgery, biopsy guidance, and molecular therapy imaging.
• The work-in-progress SENSE (sensitivity encoding) technique utilizes multiple coils and receivers to reduce scan time. The experimental technology acquires the MR signal simultaneously with a number of surface receiver coils arranged so as to overlap body areas. Typically, the more coils used, the faster the acquisition.

Shimadzu Medical Systems

• The absence of the Magnex Epios line of 1.5-, 1, and 0.5-tesla scanners in the Shimadzu booth was explained Dec. 2, when Shimadzu informed SCAN of its decision to halt MRI sales outside the Japanese market. The vendor pointed to declining sales and high production costs as the rationale for its decision (SCAN 12/15/99).

Siemens Medical Systems

• Grabbing most of the attention in the Siemens booth was the work-in-progress open 1-tesla scanner. With a launch date set for mid-2001, the company expects to have enough time to outfit the still unnamed scanner with the coils and clinical capability commonly found on a conventional high-field system (SCAN 12/15/99).
• MRease, Siemens’ new software platform for MRI, combines the company’s new software architecture, called syngo, with the firm’s proprietary Integrated Panoramic Array coil technology. MRease speeds the exam by simplifying operator procedures. Pending FDA clearance, the company will release a 16-element panoramic array coil for peripheral vascular imaging featuring a circular polarized phased-array design. MRease and the coils are compatible with the 1-tesla Harmony and 1.5-tesla Symphony.
• Magnetom Open Viva has been switched from a hybrid resistive to a permanent magnet, pending FDA clearance. The work-in-progress system maintains the open C-shape of the former product, its 0.2-tesla field strength and 15 mtesla/m gradients, while reducing operating expenses associated with a hybrid resistive magnet. The new Open Viva, which is expected to begin shipping in the spring, will support fat saturation and some contrast-enhanced MRA sequences.
• Siemens’ alliance with Bruker Medical was highlighted as the means for development of a new whole-body 3-tesla system. Like the existing Magnetom Allegra, a dedicated 3-tesla brain scanner, the new very high field system is being designed to be compatible with existing Siemens MRI technology.

Toshiba America Medical Systems

• The 1.5-tesla Excelart features a compact magnet and flared bore. The 65.5-cm-diameter aperture, billed as the widest cylindrical opening on the market, helps alleviate patient discomfort.
• The Pianissimo work-in-progress option addresses patient comfort from a novel perspective, reducing by 90% the noise that typically accompanies MRI exams. This reduction is achieved by isolating the gradients inside vacuum chambers and independently supporting the gradients from the floor. The result is a dramatic reduction in the noise associated with gradients.
• Another high-field work-in-progress is SuperFASE, a fast sequence designed specifically for vascular studies in the abdomen and chest. With SuperFASE, veins and arteries can be visualized simultaneously without the need for contrast agents.
• Upgrades of the Opart 0.35-tesla open scanner were all works-in-progress. These included four multichannel R/F coils, one each for the breast, neck, extremity, and head; an in-room fluoro monitor; a motorized, multidirectional table; and version 3.0 operating software designed to reduce scan times and enhance DICOM data management.