MR vendors innovate at RSNA meeting

Siemens brought two blockbuster MR offerings to the 2009 RSNA meeting: the 3T Skyra and 1.5T Aera. Works-inprogress pending U.S. Food and Drug Administration (FDA) clearance, the products are scheduled to begin shipping by mid-2010.

The 70-cm bores add to productivity by reducing patients' anxiety, thereby reducing the chance they will stop the exam before it's done. They also provide the room to scan obese patients. The scanners' short cylinders allow many studies to be completed with the patient's head outside the bore.

Automation that simplifies complex scan tasks makes image quality less dependent on the skill of the technologist running the machines. In preliminary testing at one site in the U.K., Siemens found that the number of technologists able to do cardiac MR exams expanded from two to 14.

The premium 1.5T and 3T scanners will demand premium prices in their field strengths. Sales efforts at the RSNA meeting, however, framed the two new products as cost-effective answers for high-volume operations.

Many of the advantages are due to the company's next-generation Tim (total imaging matrix) technology, which is built into both devices. This fourth generation (4G) accelerates scans, leveraging ultrahigh-density coils that transmit data through more channels than ever before. The new Tim's patient-adaptive technology further speeds scans by cutting the time needed for setup.

The automation that makes the predicted gains in productivity possible is built into Tim+Dot (day optimizing throughput), which simplifies complex tasks through patient personalization routines, user guidance, and exam automation. Reducing the dependence of sites on the skill of their technologists increases image consistency and diagnostic confidence while increasing throughput, according to Walter Märzendorfer, CEO of MR Imaging at Siemens Healthcare.

Both systems feature Siemens' proprietary TrueForm magnet design, which provides up to 50% more imaging volume. Homogenous images are sharp all the way to the edges of the 50 x 50 x 45-cm field-of-view.

The ultrahigh-density coils featured on these scanners have up to 204 elements. Combined with a new radiofrequency design that includes up to 64 RF channels, the new scanners can achieve a signal-to-noise ratio increase of up to 20%, according to the company. This allows high spatial and temporal resolution that does not degrade when zooming in on images.

HIGH-END APPLICATIONS

A high-field, wide-bore MR scanner from GE Healthcare also made its first appearance at an RSNA meeting. The Optima MR450w is the company's first such wide-bore scanner and at the meeting GE emphasized its clinical capability.

The 70-cm bore caters to patient comfort and increased efficiency, but not at the expense of image quality, according to GE. Company executives said the new scanner provides full fieldof- view coverage for the whole body, including the spine, abdomen, and pelvis. The only tradeoff between the wide-bore product and the company's conventional-bore, research-oriented Discovery MR 450 counterpart is gradient strength.

But the gradients onboard the Optima MR 450w are capable of performing any kind of clinical exam, according to the company. GE showed multiple examples of high-end applications possible with the device. Among them were high-resolution diffusionweighted brain imaging with techniques that correct for susceptibility artifacts and eliminate those due to dental and surgical implants, two-station wholespine imaging, breast and abdominal scans demonstrating fat suppression, and renal scans done without injected contrast.

CONTRAST-FREE EXAMS

Toshiba laid the groundwork for entering the 3T marketplace in the U.S. with the unveiling of its Vantage Titan 3T system. The work-in-progress, which is pending FDA clearance, leapfrogs earlier generations of 3T scanners with a 71-cm tapered aperture and Pianissimo noise reduction technology.

The new wide-bore system incorporates the ability to perform a variety of contrast-free MR angiography exams. Among them are fresh blood imaging (FBI) for evaluating peripheral vascular diseases of the lower legs and extremities, contrast-free improved angiography (CIA) for easier visualization of smaller vessels, time-spatial labeling inversion pulse (Time-SLIP) for evaluating hemodynamic functional assessments and visualization of vascular structures, and time and space angiography (TSA) to create noncontrast time-resolved imaging with high temporal resolution.

Toshiba's Atlas coil technology is integrated into the table to reduce the need for patients to be repositioned for different exams. The product is being designed with a new user interface called M-Power that promises to simplify training and operation.

CLINICAL WORKHORSE

Philips Healthcare executives believe the MultiTransmit parallel RF (radiofrequency) technology built into the company's flagship 3T scanner will help make 3T a clinical workhorse.

This technology overcomes two of the major challenges facing Philips' Achieva 3.0T TX: dielectric shading effects, which can obscure signs of disease from the neck to the hip, particularly cancer in the breast and liver, and limited scan speed due to tissue heating, as measured by specific absorption rate (SAR).

MultiTransmit parallel RF adjusts multiple radiofrequency transmissions to the shape and size of each patient, effectively canceling out dielectric shading, according to Deepak Malhotra, vice president of Philips' MR marketing. This is especially important for oncologic applications, as high-quality imaging of the body and breast is critically important when diagnosing and staging tumors.

The strength of MultiTransmit parallel RF is in its ability to adapt 3T scans to fit individual patients, even if circumstances are not ideal.

“With 20 scans you will have 20 different patients with 20 different sizes and shapes,” Malhotra said. “We're finding great improvement in uniformity and consistency of image quality from one patient to the next in breast and abdominal imaging.”

Transmitting parallel RF energies also reduces SAR levels to the specific areas of the body being scanned. This cuts the amount of downtime between scans, trimming exams and increasing productivity. Faster exams have the side benefit of requiring fewer patient retakes, which further improves productivity.

A luminary at the University of Vermont told Malhotra that the MultiTransmit technology eliminated the need to administer anesthesia when doing pediatric abdominal scans.

About 95% of Philips' 3T systems installed around the world are upgradable to MultiTransmit parallel RF.