Law of Attraction: 3T MRI Hits the Mainstream

This 3D image of white matter tracts in the brain was obtained using Siemens syngo DTI Tractography which enables 3D visualization for improved neurosurgical planning based on diffusion tensor imaging (DTI) up to 256 directions. Image courtesy of Tianjin Huanhu Hospital, Tianjin, P.R. China

3T MRI scanners are attracting a lot of interest these days. The first mega-magnet systems hit the market about five years ago, but the technology wallowed in the academic medical and research realms—until recently.

3T MRI is ready for prime time, and prime time is ready for 3T. Several factors account for the turning tide. A number of sites are replacing 1T and 1.5T systems. Given the high acquisition cost associated with a new scanner, many are looking to the future and recognize that 3T is the way to go. That’s because coil technology —the enabler of clinical applications—has caught up to magnet development, which means 3T sites can perform routine MRI scans and add volume with new offerings such as breast MRI, MR angiography and cardiac scanning.

Like all fiscally savvy imaging investments, 3T delivers beyond the clinical realm. 3T MRI is a workflow powerhorse, enabling sites to cut scan time, improve patient throughput and better the bottom line. Early adopters run the gamut from academic sites to imaging centers and community hospitals. Despite differences in patient population, goals and clinical mix, implementers agree—3T is a winning venture.


Delayed gratification

William Muhr, MD, director of body imaging at South Jersey Radiology Associates in Voorhees, N.J., admits to early fascination with 3T MRI. “We became interested and intrigued with 3T several years ago and realized that the technology could deliver distinct benefits. By the same token, the early systems weren’t quite where our practice wanted them to be. They were more geared toward research applications; coil technology was not mature or ready for clinical applications.”

So the eight-site diagnostic imaging practice waited, and last year realized that the 3T era had arrived. The practice decided to replace a 1.5T MR scanner with a Siemens Medical Solutions Trio 3T system. The newest acquisition incorporates TIM (Total Imaging Matrix), which leverages the full capability of coils and enables whole-body applications.

South Jersey Radiology Associates launched the new scanner with a fairly ambitious goal, aiming to use 3T for both routine imaging and new applications limited by resolution or other aspects of 1.5T scanning. “The primary benefit of 3T is that it offers more signal,” explains Muhr, “which can be used to optimize parallel imaging, allow diffusion tensor imaging for neurological or orthopedic applications, or to cut scan time.”

Since deploying the Siemens system earlier this year, the practice has managed to exploit its diverse capabilities. For example, the 3T Trio has become the scanner of choice for small joint imaging. “Wrists, fingers and toes are beautifully seen on 3T. These scans tend to be hit-or-miss with 1.5T MRI scanners,” states Muhr. The benefits of 3T extend beyond small joints; the scanner also can be used for routine knee imaging to produce higher resolution scans or to cut scan time. In fact, South Jersey Radiology Associates runs a full schedule on its Siemens 3T system, but with shorter scan times. The standard 30-minute MRI appointment drops to 20 minutes on the 3T system. “It’s a significant productivity gain. The limiting factor is the time that it takes to get the patient on and off the table,” says Muhr.

The new scanner has required some training and tinkering. “Technologist and radiologist education is the most important factor in the deployment. Everyone needs to understand what 3T can and can’t do,” explains Muhr. At the tech level, techs need to realize that artifacts can occur and must wrangle with increased specific absorption rate (SAR) restrictions. A solid understanding of SAR, or radiofrequency energy measurements, and MRI sequences can help improve scan efficiency because if a scan reaches the restrictions, it is stopped. South Jersey Radiology Associates trained two lead techs in 3T applications and relied on them as super-users who could train other techs. The front desk also plays a key role; schedulers need to be educated about 3T and route appropriate studies—such as hand and wrist scans—to the 3T system.

The final piece of the puzzle is a work in progress at South Jersey Radiology Associates. The practice is planning a robust educational campaign for referring physicians, detailing the benefits of 3T for hand surgeons, neurologists, oncologists and other referrers. As the referring physician community enhances its understanding of 3T, the practice expects to begin to realize the full benefits of 3T operations.


The competitive edge

Fort Atkinson Memorial Hospital in Fort Atkinson, Wis., operates in a tough environment. The 110-bed community hospital serves a population of 65,000 and is squeezed between two metropolitan areas. A number of patients are referred to the larger, city hospitals for various procedures. These factors played a critical role three years ago when the hospital undertook a major expansion, including moving the radiology department to new quarters.

At that time, the radiology department was faced with a difficult decision. Did it move an old 1T system to the new site or upgrade to a 1.5T scanner or even 3T? “We knew a 1.5T scanner would meet current needs, but we were concerned that the technology would grow outdated very quickly,” recalls Imaging Director Cathy Hovel. The other, related concern was competition and revenue. The hospital realized it might lose imaging patients to the larger, regional sites if it fell behind in technology.

The radiology department convinced hospital leadership to invest in GE Healthcare’s 3.0T HD Signa MRI system and installed the new scanner in December 2005. When the new scanner was first installed, MRI volume stood at 120 scans monthly. In the 18 months since deployment, volume has risen sharply, and the small hospital now performs 200 scans a month. Procedures include routine clinical studies such as basic neurological scans, spinal work and musculoskeletal exams on knees, shoulders and hips. Some growth is, however, due to new scans enabled by the 3T system—such as carotid MR angiography and breast MRI scans.

The hospital has realized several benefits of 3T. “We’re keeping patients here because we’ve gained the confidence of attending physicians. They realize that this small community hospital can provide the same quality as our colleagues in the cities,” notes Hovel. Now, when a patient travels to a metropolitan hospital for a procedure, physicians no longer request that follow-up imaging be completed at the remote site. Instead, MRI scans are performed at Fort Atkinson Memorial Hospital. “It’s essential to have top-notch technology to promote diagnostic confidence among attending physicians,” says Radiologist Edgardo Jiangco, MD.

Productivity is another key advantage; the hospital has cut scan times by up to 40 to 50 percent since installing the 3T system. In fact, it has significantly increased volume without adding staff. Finally, the advanced technology sends a message to new physicians. “It’s a great recruiting tool to help lure new physicians to the area,” confirms Hovel.

“This scanner was the right choice for our hospital,” sums Hovel. “Our numbers have increased, and we’ve improved patient care and the hospital’s standing in the region.”
 

From left: High resolution image of the Circle of Willis. Vascular Imaging with TRICKS provides excellent vessel visualization in the hand. Vascular imaging with TRICKS provides excellent vessel visualization in the wrist. HDMR provides large field of view of carotid arteries. Images acquired on the GE Signa HD 3T system.

A flexible platform

The radiology department at Hennepin County Medical Center in Minneapolis, Minn., had 3T MRI in its strategic vision for several years before the opportunity to invest in a new system presented itself. “We jumped at the chance to deploy 3T in 2004 and have not looked back,” confirms Chief of Radiology Charles Truwit, MD. The center installed Philips Medical Systems’ Intera 3T system and has implemented a robust clinical application regimen.

“The increased signal-to-noise ratio is tremendous for many reasons,” says Truwit. “We can take advantage of it for high-resolution studies like MR angiography or use the time value of the signal to accelerate throughput, which is ideal for busy outpatient centers or dealing with claustrophobic patients.” The 3T system streamlines and improves advanced applications that are possible but not ideal with 1.5T magnets like BOLD (blood-oxygenation-level-dependent) imaging; the center had performed the advanced techniques with its 1.5T magnet, but the process was “cumbersome,” says Truwit.  Another up-and-coming application is DWIBS (diffusion weighted imaging with background signal suppression) that produces PET-like images on the MRI scanner and could benefit lymph node scans. Finally, the short-bore system is accessible for clinicians and can be used for procedures including MRI-guided neurosurgery.


An attractive future

3T MRI is growing up and garnering increased interest among all types of imaging operations. “3T will become routine clinical practice,” predicts Truwit. Hennepin County Medical Center and other 3T sites are eyeing the future. A host of advances promise to ignite the field.

The ability to upgrade to a 16-channel system on 3T will bring another quantum leap forward, says Truwit. The freewave platform that enables 16 or more channels allows parallel or SENSE (for Philips’ users) imaging, which increases the signal-to-noise ratio. The increase translates into improved spatial resolution; for example, 3D angiographic data can be made more exquisite with smaller branch vessels displayed. Alternatively, the system can be used to improve temporal resolution and viewers can watch arterial and then venous flow imaging in the heart, lungs or brain. Early data indicate that the 3T 16 channel spine provides advantages in signal and image quality over the 1.5T; similarly, early returns on the 16-channel torso coil show significant improvements in signal and image quality in the abdomen.

Other applications high on the wish list include cardiac and breast MRI scanning, with many 3T sites adding breast coils to the MRI mix. “We will see 3T breast imaging start to take off,” says Muhr, even though the application currently lacks reimbursement. MRI can meet two-breast imaging needs as it is ideal for high-risk screening and also may be used to stage breast cancer patients. Muhr predicts that current research applications will transition into clinical practice over the next few years. Other oncology applications could increase as 3T proves its merit in whole-body metastases screening.

High-field MRI may be the new kid on the block, but it is poised to mature as more sites replace aging systems and lay a solid foundation for the future. The demonstrated benefits of 3T MRI include:

• a platform for a wide range of advanced applications
• increased resolution or accelerated throughput
• market leadership and differentiation

What’s more, now is an ideal time for 3T. Coil technology has matured, and systems are universally user-friendly. Magnets are better designed and shielded, so siting is simplified. Finally, a new system with an upgradeable magnet offers an easy transition path from 1.5T to 3T.