Novel technologies push MRI in new directions

Manufacturers are exploring new capabilities and novel technologies that promise to bring down long-standing MRI performance barriers and improve patient comfort. This modality, which for so long has been characterized by field strength, is redefining itself.

Gone is the time when a single open mid-field or low-field scanner was enough for a manufacturer. Vendors are now putting together a range of offerings from which customers can choose different performance and price points.

Patient comfort has become the "clinically correct" way of thinking, as manufacturers seek new ways to reduce or prevent stress during a procedure. Noise reduction, a concept pioneered by Toshiba America, is an approach that's been picked up by other companies.

Engineering capabilities are being tested as the means of achieving new levels of performance. One path being explored is a dual-gradient system developed by GE Medical Systems that promises general purpose and specialty capabilities in the same unit.

While different engineering priorities may vie for the attention of manufacturers, the overriding concern is clinical application. This need is driving firms to reach above 1.5 tesla into the very high range. With Marconi, Philips, and Siemens joining GE this year in the production of 3-tesla systems, industry insiders expected sales of these systems to triple last year's sales level of about 20 scanners.

Fonar

• Indomitable, previously known as Stand-up MRI, was at the front of the Fonar booth. The 0.6-tesla system scans standing patients for weight-bearing diagnosis of orthopedic problems. Indomitable, first shown as a work-in-progress in 1996, received FDA clearance in October. It is being sold directly by Fonar and by GE Medical Systems under a distribution agreement announced in August 2000.
• Fonar-360, an MRI built into its scan room, took center stage at the company's exhibit. Two circular structures, composed of the magnet and gradients, project from the ceiling and floor. The company showcased the system, which received FDA clearance in March, as the ultimate in open design for diagnostic and interventional procedures.

GE Medical Systems

• Signa Ovation, a 0.35-tesla open scanner, now rests between GE's 0.7-tesla OpenSpeed and its 0.2-tesla Signa Profile. Ovation supports the same set of clinical procedures as Profile but provides a better signal-to-noise ratio. The company has not determined if or when the open product line will expand beyond 0.7-tesla. Its major emphasis remains on the development of cylindrical scanners, according to GE.
• Signa OpenSpeed is in full production with more than 20 systems shipped. Siting problems encountered at the first installation in early 2000 have been solved, according to the company. Underscoring that point, GEMS is offering a $1.5 million turnkey package, which includes the purchase and installation of OpenSpeed.
• Signa TwinSpeed features a dual-gradient design. The body coil allows general-purpose imaging. Higher resolution and increased speed are possible when using the second gradient. The trade-off is a narrower field-of-view, which should not interfere with its intended use for specialized studies of the brain or heart, as well as high-resolution orthopedic imaging. TwinSpeed features acoustic reduction technology that cuts noise by 40%. The new 1.5-tesla scanner should go into production in the latter half of 2001. GE showed the prototype as a work-in-progress at the 1999 RSNA meeting, but the system is based on technology first developed by Elscint. The basic platform was acquired when Elscint's MRI assets were purchased by GE in 1998.
• An integrated whole-body coil enhancement for the Signa VH/i (very high field) is being tested and further developed. Spine images measuring 40 cm have been achieved using Signa. The company demonstrated a work-in-progress head gradient coil, which has an amplitude of 100 mtesla per meter and slew rate of 1000. Expected release date for the coil is 12 to 18 months out.
• The fusion of MR and 3-D x-ray images is being studied as a means for planning treatment of vascular brain disorders. Images are fused using the 3DXR/MR package, running on an Advantage Windows 3.1 or 4.0 multimodality workstation. Fused images can be viewed as a single picture with gray-scale MR images registered with colorized x-rays. Alternatively, x-ray and MR images can be displayed side by side.

GE Lunar/Esaote

• Acquisition of Lunar in August gave GE its first dedicated orthopedic systems. As an independent vendor, Lunar had sold orthopedic MR scanners in the U.S. since the early 1990s. The two models currently in the lineup, Artoscan M and E-Scan, are provided by Italy-based Esaote, which also supplies Siemens with a version of the E-Scan under the Magnetom Jazz designation.

Hitachi Medical Systems America

• Altaire was showcased as a higher field open product. Altaire represents Hitachi's best hope of breaking into high-field sales. Shipments of the 0.7-tesla superconducting system, which cleared the FDA in October, are scheduled to begin in first quarter 2001. Company strategists hope to capitalize on the firm's reputation and extensive installed base of open 0.3-tesla systems to generate higher field sales. The vertical field scanner offers high-field image quality, according to the company. Passive shielding maintains the 5-gauss fringe field within an 18 x 22-foot room. Imaging applications include single-shot echoplanar imaging (EPI), MR angiography with very short TEs, radio-frequency fat saturation, and fast spin-echo imaging with short interecho time.
• Clinical enhancements for Airis II, Hitachi's mainstay 0.3-tesla open system, will be available to customers in 2001. Among these are EPI-based diffusion-weighted imaging and an advanced fat-water separation technique for neurologic and orthopedic applications. Also added were contrast-enhanced MRA and advanced reconstruction techniques using time-of-flight MRA.
• In development are two multiple-array coils: a knee/foot/ankle multiple-array coil and a peripheral vascular coil.

Marconi Medical Systems

• Infinion HFO (high-field open) combines the image quality of a high-field system with the patient comfort of an open design, according to Marconi. The C-arm design, which resembles that of the company's low-field ProView, allows patient access on three sides. The 0.6-tesla magnet in the new system includes a superconducting element, whereas the low-field systems do not. The new open system, which is expected to be in production before the next RSNA meeting, is one member in a new family of products bearing the Infinion name.
• Infinion 3T, the company's work-in-progress very high field product, is designed as a whole-body system but is being optimized for neurologic applications. Its MicroDrive gradient system allows the operator to switch between body and head protocols in less than a minute.
• Infinion 1.5T, a work-in-progress high-field scanner, was billed as the world's shortest whole-body MRI, featuring a flared gradient technology that maximizes the aperture and improves patient comfort. A collaboration with Oxford Magnet Technology led to the development of a compact magnet that reduces the length of the system to 1.4 meters. The system features a fully removable patient table combined with built-in surface coils. With Via software, the Infinion 1.5T can be optimized for MR cardiology as well as functional brain imaging. Other applications include oncology therapy planning, interventional radiology, and emergency medicine involving trauma patients.
• Via 3.0 software features interactive imaging, which is useful in targeting tissues within the body, as well as ensuring correct patient positioning. It also allows the monitoring of contrast uptake. The package is designed specifically for use with the 1-tesla Polaris and 1.5-tesla Eclipse systems. Cardiac acquisition and analysis and functional brain imaging are key clinical capabilities supported by Via 3.0.
• ProView, the company's low-field scanner, has been enhanced with diffusion-weighted imaging and a breast coil to support biopsy.

Millennium Technology

• Enhancements in hardware and software have improved the speed and performance of Virgo, the company's open design 0.35-tesla scanner. The C-shaped permanent magnet system, which made its first RSNA show appearance in 1999, is built from off-the-shelf components. It runs on Java commands and Windows NT. Millennium's corporate strategy is to develop a value product capable of performing a wide range of routine MRI applications.
• Virgo is the first in a planned family of products. Next up is likely to be a smaller specialty unit, dedicated to a specific part of the body, although high field is being considered. The new unit could appear as early as the next RSNA meeting.
• MR angiography and EPI are planned for release by fall.

ONI

• OrthOne made its first appearance at the RSNA meeting. The 1-tesla dedicated orthopedic scanner, which uses superconducting technology, was officially released in August. The 28-cm bore of the cylindrical scanner (which is mounted inside a pedestal stand) is wide enough for an arm or a leg. A reclining chair swivels the patient into position. The entire system can fit in a 10 x 10-foot room. With a list price of $425,000, the new system is about half the price of a general-purpose low-field open scanner. Production should be at full capacity by the early part of 2001.

Philips Medical Systems

• Panorama 1.0T, a work-in-progress open high-field system, complements Philips' 0.23-tesla Gyroscan Panorama. As an actively shielded system, Panorama 1.0T offers siting advantages over competing open products that require extensive external shielding. Panorama 1.0T also promises weight advantages. At 13,000 pounds, it is about a quarter of the weight of some competing products.
• The Gyroscan Panorama, a low-field open system manufactured by Marconi, debuted at the RSNA meeting, having been added to the Philips label in March. Gyroscan Panorama, although physically similar to Marconi's ProView, has been outfitted with imaging sequences and an interface that match those in the Gyroscan family. When the Panorama 1.0T becomes available, the low-field open will provide Philips customers with a choice of open systems at different performance and price points.
• Intera 3.0T, the company's very high field unit, is scheduled to begin operation at clinical test sites in early 2001. Unveiled as a work- in-progress, the magnet fits the same compact box as the rest of the Intera family and offers a bore diameter of 60 cm. Its user interface and pulse sequences are the same as those on the Philips 1.5-tesla product. The actively shielded unit eases siting requirements and minimizes related costs. The 3-tesla unit will be oriented mostly toward brain and cardiac applications, offering morphological and BOLD imaging of the brain, including spectroscopy, diffusion-weighted imaging, and perfusion-weighted imaging. In development and scheduled for inclusion on the system is diffusion tensor imaging. Intera 3.0T will be outfitted with SENSE (sensitivity encoding) technology, which uses multiple coils to optimize temporal resolution without sacrificing image quality.

Shimadzu Medical Systems

• Having withdrawn from the North American marketplace in 2000, Shimadzu's MRI division completed its retreat by phasing out sales of its own line of systems from the Japanese market. Shimadzu now distributes MRI systems made by Marconi Medical Systems to the Japanese market, building on the distribution relationship that began with Picker International's nuclear medicine equipment.
• Coil upgrades for the current installed base of Shimadzu MRI scanners are promised. No software is currently being developed.

Siemens Medical Systems

• The 1-tesla open scanner, announced at the 1999 RSNA meeting, was officially named Rhapsody at the 2000 show. Rhapsody is expected to ship to a clinical site in summer 2001, with routine deliveries in the U.S. expected before the end of 2001. Application to the FDA was made just prior to the 2000 RSNA show. The commercial product will have the same capabilities as Siemens' high-field conventional products (1-tesla Harmony and 1.5-tesla Symphony), including spectroscopy and advanced cardiac functions. A stepping table will be included to allow peripheral MRA runoff exams. The company's Integrated Panoramic Array Coils and a full complement of extremity coils will be included.
• Concerto is among the new names joining the Siemens lineup. The 0.2-tesla open scanner, which has yet to be cleared by the FDA, is essentially an enhanced version of the previously marketed Open Viva P (permanent). The magnet is the same, but the actively shielded flat gradients, capable of 20 mtesla per meter amplitude, are new. Also new is the MR ease front end, which makes system operation the same as that of other Siemens MR scanners. Concerto's C-shaped permanent magnet is combined with the company's Integrated Panoramic Array Coils. Installed Viva P units are upgradable to the Concerto configuration.
• Trio, a 3-tesla whole-body scanner, is poised to enter the marketplace. The first clinical test site could be installed by early summer 2001, with routine shipments by early 2002. The system is being developed in cooperation with Bruker. Siemens provides the magnet, gradients, and interface, as well as sales and service support. Bruker provides the RF chain to support multinuclear imaging and spectroscopy. Bruker also serves as the system integrator.
• Allegra, the company's 3-tesla dedicated neurology scanner, received FDA clearance three weeks prior to the RSNA meeting. The system is now geared up for full production. Development of the unit is continuing in collaboration with academic luminaries.
• Symphony and Harmony can now be configured with 16 rather than a mere eight channels to better support the Integrated Panoramic Array capability. New body flex-array coils are available, as well as an option for extending the field-of-view. A dedicated peripheral angiography coil, first shown at the 1999 RSNA meeting, is in full production.

Toshiba America Medical Systems

• Excelart XG, a work-in-progress high-field scanner, features enhancements on the Excelart platform, including stronger gradients and a faster computer. Clinical applications are bolstered by new cardiac and spectroscopy packages. The work-in-progress Cardiac 2001 Package supports the study of cardiac morphology and function, as well as imaging and quantification of blood flow. The MR Brain Proton Spectroscopy, also a work-in-progress, is designed to improve patient management of various brain-related abnormalities. A new generation of SuperFASE enables the visualization of vascular flow without the use of contrast media.
• Pianissimo Plus is the latest high-field noise reduction technology. Exhibited as Pianissimo at the 1999 RSNA meeting, this technology reduces noise through structural techniques, including vacuum chambers and struts that limit contact between the gradients and the rest of the scanner. New this year are pulse sequences that minimize noise without compromising image quality, according to Toshiba. Pianissimo Plus is designed as part of the Excelart platform.
• Opart, the 0.35-tesla superconducting open scanner, appeared in a three-tier set of configurations. Each tier addresses a specific market segment. The high end, called Paragon, features enhanced electronics and a standard set of 10 coils. It supports advanced clinical applications, including diffusion-weighted imaging, perfusion-weighted imaging for stroke detection and staging, and fluoroscopy. This high-end configuration is intended to provide the wider range of clinical applications required in clinically demanding settings such as large hospitals, universities, and research centers. The mid-tier Potenza has seven standard coils and supports several advanced capabilities, including fat-water separation. Potenza is designed primarily for small community hospitals. The low-tier Prodiga comes with four standard coils and is intended primarily for clinics that do mostly orthopedic imaging.