High-field open MR scanners generate first clinical results

A new type of MR scanner began operating in October. Staff at a Las Vegas outpatient clinic owned by Nevada Imaging Centers claim the 1T scanner produces images as good as or better than those of 1.5T systems, scans patients as fast as a closed high-field system, and does so using an open design.

"Artifacts are less," said medical director Dr. Gary McLellan. "Image contrast, by some measures, is better than our 1.5T."

Nevada Imaging Centers has five outpatient clinics running five MR scanners, each at a different field strength. Philips' new Panorama 1.0T excels at cervical spine imaging, the bread and butter of routine MR practices, according to McLellan. He compares the image quality and scan times favorably with scans taken at 1.5T.

"We have done images on people where we have seen no pulsation artifact," he said. "And truncation artifact is very small-nonexistent in some cases."

Patient volume is still climbing at Nevada Imaging's newest clinic. The center that hosts the Panorama 1.0T only opened in October, but within several weeks, the staff had managed nine patients in a single day on the new open high-field system. Pat McLellan, practice administrator for the five imaging centers, predicts the scanner will routinely handle 20 patients a day. She expects demand to rise rapidly.

"Obviously, we'll be getting the obese and claustrophobic patients, but this system is also especially suited to pediatric patients," she said. "Parents feel more comfortable because they can see their child, and the children are more comfortable because they can see their family."

Orthopedic patients will benefit as well. The Panorama 1.0T offers a large field-of-view, which helps in positioning joints in the isocenter of the magnet, Pat McLellan said.

The Panorama 1.0T uses many of the same components as Philips' flagship cylindrical 1.5T Achieva. It differs in its use of an actively shielded vertical field superconducting magnet, which is open on all four sides. Because of its unique architecture, the Panorama 1.0T requires specially designed coils.

Philips designed the magnet, which is being supplied by its partner Intermagnetics General, to restrict the 5-gauss line to that of a 1.5T cylindrical unit. This step overcomes the siting problems that had been an issue with earlier 1T open designs, according to Jacques Coumans, Philips vice president of MR global marketing. The company also reengineered the magnet and gradient system to reduce costs, which had been prohibitively high. Gradients operate at an amplitude of 26 mT/m and a slew rate of 80 T/m/sec.

The high-field open scanner can be used with dockable tables that allow one patient to be scanned while another is being prepped, said Hans Kleine Schaars, director of the MR radiology business segment for Philips.

"This configuration is designed primarily for entrepreneurial centers, where throughput is very important," he said.

The Panorama 1.0T has been a long time coming. It was first shown at the RSNA meeting five years ago as a work-in-progress. At this year's meeting, Philips was preparing for full production, which is slated to begin in mid-2005. By then, the company expects to have about 10 sites in operation.

Interest in 1T MR scanners, once viewed as an economical alternative to high-field systems, has all but evaporated over the last several years. Falling prices for 1.5T systems and R&D aimed at expanding the clinical reach of these systems worked against the popularity of cylindrical 1Ts. The Panorama 1.0T could rekindle this interest by offering a high-field alternative for patients who cannot or prefer not to enter cylindrical systems.

For this reason, Philips plans to charge a premium for its new open product. Company executives have provided some room for negotiation, publicly placing the price above that of a 1.5T system but under that of a 3T.

"We feel the value proposition warrants such a price positioning all around the world," Coumans said.

Gary McLellan has achieved encouraging results in a wide range of applications, including MR mammography. His staff will soon attempt cardiac imaging and peripheral runoff angiography made possible by Philips' own MobiTrak moving table technology, which was developed for use on its high-performance cylindrical systems.

"This machine is designed to do pretty much all the applications you can do on Philips' top-of-the-line 1.5T system," he said.

These applications run on the Panorama 1.0T with only minimal adjustments to sequences developed for 1.5T systems, according to McLellan, whose staff uses Philips' ExamCards containing protocols for optimized MR exams. Scan parameters are downloaded into the scanner directly from these electronic files, which also contain help text and examples of clinical images.

"We started with standard 1.5T protocols from the Philips short-bore system and exported them over," McLellan said. "We modified them a little, with experience, but having the ExamCards meant we didn't have to start from scratch."

ExamCards are available to Philips' installed base via the Web, many of them contributed by users of Philips equipment. Sequences are customized for different field strengths.

Taxonomy

Imaging Specialties: Vendor; Head and Neck

Medical Specialties: Radiology

Modality: MRI

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2/1/05, Issue # 2702, page 47.