TECHNOLOGY & INDUSTRY Magnetic resonance imaging update

Open-bore 1.5T system—Siemens Medical Solutions (Malvern, PA) recently introduced an open-bore 1.5T magnetic resonance imaging (MRI) system, the MAGNETOM Espree. This system was designed to provide high field strength, a broad spectrum of applications, and more open space in order to address issues related to patients who are obese, claustrophobic, elderly, or pediatric.

The new system’s 125-cm bore allows <60% of scans to be completed with the patient’s head outside of the bore. The opening is 70 cm in diameter, and the average distance between a patient’s head and the magnet is almost 1 foot.

The Espree system also provides a greater signal-to-noise ratio than does a traditional open MRI design and includes the company’s proprietary Total imaging matrix (Tim) technology. Tim is a whole-body surface coil concept designed to provide high-resolution images with a short acquisition time.

“All patients deserve the same access to high-quality MRI technology, which is used for detection, diagnosis, and treatment planning for cancer, diabetes, heart disease, vascular disorders, and other diseases associated with obesity,” said Nancy Gillen, Vice President, Magnetic Resonance Division, Siemens.

Compact, C-shaped MR system—The second new MR product from Siemens is the Magnetom C! with a compact, midfield, C-shaped magnet with a pole diameter of 54 inches. This new system, which is open on 3 sides, allows for 270˚ of accessibility.

The Magnetom C! features multichannel imaging that allows for the simultaneous placement of up to 4 coils, which provides greater anatomical coverage area, increased patient comfort, and shorter scan times. The suite is available for neurologic, orthopedic, angiographic, body, oncologic, cardiac, and pediatric applications.

The system includes workflow support through the company’s proprietary syngo user interface, as well as the Phoenix technique to exchange protocol data. The system also features a multichannel application suite with a range of multichannel coils, and a multichannel radiofrequency (RF) and gradient system. Advanced techniques for the system include 2D PACE (Prospective Motion CorrEction) high-field technology for free-breathing abdominal studies without artifacts, inline technology for processing instead of postprocessing, and iPAT (integrated Parallel Acquisition Technology) functionality for high spatial and temporal resolution.

Lawrence N. Tanenbaum, MD, FACR, Section Chief MRI, CT and Neuroradiology, Edison Imaging—New Jersey Neuroscience Institute, Edison, NJ, was recently elected President of the Clinical Magnetic Resonance Society (CMRS). Dr. Tanenbaum is also a member of the editorial board of this journal. In a recent interview with Applied Radiology, he outlined the goals of the society and his vision for his tenure as President.

“We have several components to our mission,” he explained. “One of our goals is to serve as an advocate on the national stage for the clinical practitioner of MRI. Another is to provide clinical practice-based credentialing in general and sub-specialty areas of MR; to give an additional credentialing and legitimacy to our member radiologists in the active clinical practice of MRI, which can help in establishing their expertise and differentiation from causal practitioners of MRI.”

“The third and perhaps most important goal,” he continued, “is to provide a means for practical, clinical education. There is no society solely dedicated to assisting clinical practitioners of MRI—generally in community practice—and updating them on a regular basis with developments in MRI. Our annual meeting offers a very large technical and professional component specifically designed for the needs of the clinical practicing radiologist and technologist.”

As President, Tanenbaum is committed to strengthening the society by increasing its value to its members. One of the major steps he plans is enhancements to the society’s Web site, www.cmrs.org. The first goal is to have unique clinically oriented members-only content. “Our trustees are excellent sources of the latest techniques and clinical applications. In the endeavor to give our members year-round exclusive access to this resource, we will have a members-only section with protocols from head to toe at all field strengths for multiple manufacturers,” Tanenbaum explained. “We hope to give the membership an opportunity to submit protocols as well. We also plan to have members-only discussion forums in which members can chat and have the opportunity to raise issues with trustees or other members.” In addition, he intends to have select portions of the annual meeting content viewable online in the members-only section. “Under my tenure, the Web site will be significantly revamped with a focus on value to the membership,” he promised.

In addition, he plans to make the annual meeting, which has traditionally been held on the East Coast, more accessible to a broader range of members by holding it in alternating locations. “In the interest of better serving a national constituency, we plan to alternate the location of the meeting between Orlando, FL and another location within the U.S.,” he said. The 2005 meeting is scheduled for Vail, CO, on August 11–14.

“My primary goal is to make the society stronger,” Tanenbaum concluded. “To make the society stronger, I think the first thing you need is to increase your membership. To increase the membership, you have to increase the value of membership; that’s why we are going to enhance the Web site to make that more valuable. We’re also going to move our meeting out West every other year to better serve our West-Coast constituency. The best way for us to serve as an advocate is to be a strong voice for an even larger group.”

The Food and Drug Administration (FDA) recently granted marketing approval to GE Healthcare (Waukesha, WI) for the new Excite platform for its MR technology.

This new technology enables the simultaneous imaging of multiple channels in increments of 16 on the GE Signa 1.5T and 3T MR systems. As the number of channels is increased using this technology, so is the image-processing power. In addition, the coil, the receivers, and the array processors are scaled together, allowing for simultaneous imaging to be performed without processing delays.

According to the company, Excite allows for cardiac imaging at a rate of 20 frames per second, allowing for real-time MR imaging of the heart at the speed of ultrasound and eliminating the need for ECG gating and patient breath-holds.

The presence of metal objects near the powerful magnets used in MRI is a serious safety concern. Even small objects made of ferrous metal can cause severe injury—including death—to the patient, and may cause extensive damage to the equipment. In fact, a piece of ferrous metal as small as a hairpin can reach speeds <40 mph when pulled into a 1.5T magnet.

Despite extensive safety protocols and metal-detecting equipment already in clinical practice, human error still occurs. The recently introduced Ferralert Prescreen ferromagnetic detection system from Knopp Development, Inc. (Jensen Beach, FL) was designed as an adjunct screening device to help detect and locate small ferromagnetic objects that may have been missed using other screening methods.

The system is composed of two parts: the operator console and the portal. When the system is activated, it passively locates and normalizes static ferrous objects in its immediate environment, allowing them to be ignored by the system. The portal, which looks similar to the portals used to screen airline passengers, emits no electromagnetic radiation. Therefore, titanium, brass, copper, aluminum, and all other nonmagnetic materials do not trigger the alarm. As patients and personnel pass through the portal, they are screened for any ferrous metals. If a ferrous object is detected, both audio and visual alarms are activated. The console provides the operator with information regarding the object’s location, size, and ferromagnetic attraction potential.

According to the company, the adjustable sensitivity “can detect objects the size of a hairpin while ignoring a 12 × 36 × 0.062-inch thick sheet of nonmagnetic stainless steel.” It is important to note, however, that this system was designed to be used as a supplemental procedure and does not replace standard screening procedures already in place.

At the recent 2004 Summer Olympic games, a dedicated MR system was available for one relatively small group of participating athletes— the equine variety.

For the first time, there was an on-site 0.21T scanner from Hallmarq Veterinary Imaging (Guilford, UK) specifically designed to image the leg of a standing horse from hoof to hock. Traditionally, to obtain equine MR images, a horse would have to be heavily sedated and placed on a standard MR system. With this system, a lightly sedated horse is walked into the U-shaped magnet. The magnet then moves up and down to image the hoof and leg. The unit is used mainly to diagnose bone bruises, hoof injuries, and to define the generic diagnosis of “navicular disease.”