1.5T MRI Spreads Its Wings
Steinberg Diagnostic Medical Imaging Centers (SDMI) in Las Vegas uses Vantage powered by Atlas 1.5T from Toshiba America Medical Systems.

While manufacturers work on improving 3 Tesla MRI scanning to the point that it is a financially viable modality for more facilities, 1.5T is serving as an imaging workhorse. Recent studies have shown that breast MRI routinely finds previously undetected lesions and the speed and comfort of the scanners makes 1.5T MRI ideal for numerous applications.

When technologist John Byrd began his career in 1985, there were fewer than 100 MRI systems in the world. The standard exam took an hour-and-a-half to complete. The computers were the size of most living rooms. Five patients a day was the maximum the equipment could handle. “Now I do five patients before my morning break,” he says. The computers fit under a desk and exams take about 20 minutes. “The thought of a heart MRI scan back then was unthinkable. The imagination of the engineers just amazes me.”

Byrd uses Magnetom Symphony scanners from Siemens Medical Solutions which he describes as “probably the most balanced systems to do the widest variety of imaging that there is.” He also finds the equipment easy to use because the coils are integrated into the tabletop, so “it’s easier to change out the equipment. You can do multiple exams without having to get the patient up off the table. That makes a difference when you have a high-volume workload.” He’s also found the accompanying Siemens syngo software to be pretty intuitive and easy to pickup.

Biting back at breast cancer

Paul Mimmis, MD, a radiologist at St. Francis Hospitals and Health System in Indianapolis, works with two open-sided 1.5T scanners from GE Healthcare—the Signa HDe and HDX—and another three scanners at offsite campuses. He particularly appreciates that the compact equipment from GE’s newest line doesn’t require a computer room and cooling equipment. That saved the organization $50,000 to $80,000 in installation costs.

Mimmis says 1.5T MRI has made important advances to breast imaging. “I can’t emphasize enough the difference we’ve made with breast MRI,” he says. “Now, pretty much every [breast cancer] patient gets a breast MRI before surgery and one in three patients has more than one lesion in the same breast that we didn’t know about. Another 1 in 20 have a lesion in the other breast.”

If those findings are detected before surgery, clinicians can change the patient’s course of care and hopefully pave the way to a higher cure rate. “Now, we can add a contrast injection and detect cancer much sooner than we can from ultrasound or mammography.” Mimmis is excited to be making a difference and playing a major role in the blitz on breast cancer. “We’re making a difference in people’s lives and that makes a lot of people around here pretty happy about what they’re doing,” he adds.

Mimmis also uses GE’s Vibrant for breast imaging. The patent-pending software provides rapid imaging without compromising in-plane resolution. The ability to scan very quickly and look at chemical abnormalities in an area help determine whether something suspicious is scar tissue or a new tumor.

 Unfortunately, Mimmis says he sees a lot of sites not doing 1.5T MRI for breast imaging because they are not ready for the technology. “The more people we can get scanning breast MRI at 1.5T, the better.” To that end, he says he and his colleagues are always willing to help other hospitals and clinics set up and learn the equipment if they express an interest.

Prime for patients

1.5T MRI is the industry standard, and is quieter and less claustrophobic for patients, says Mark Winkler, MD, radiologist at Steinberg Diagnostic Medical Imaging Centers (SDMI), a five-site imaging operation in Las Vegas. “1.5T is a mature and proven technology that we can use for all applications.” SDMI images about 800 patients a week with MRI and uses Vantage powered by Atlas 1.5T from Toshiba America Medical Systems.

3T has garnered a fair amount of industry buzz, but Winkler says it is more of a research tool. “It’s bigger and longer and very noisy—not a pleasant experience for the patient.” Plus, 3T is not as robust for all patient studies, particularly not for imaging moving structures. 

The rapid scanning 1.5T can deliver—20 minutes compared with closer to 45 minutes for traditional scanning—is helpful for most patients. It’s tough for patients to hold still, says Byrd. But a 20-minute scan has a better chance of producing good, clear diagnostic images. “Most of the time, people are in pain. Anything to speed up the exam is going to be to everybody’s benefit.”

And doing it right the first time benefits everyone as well. Byrd has had to repeat scans done on weaker magnets because the detail wasn’t fine enough to make a diagnosis.

Those 20-minute scans also mean that users don’t need to perform that many studies a day to break even. “We have 1.5T in two outpatient clinics and they’re in the black,” says Mimmis. “You can do almost any type of MR you need to do except the advanced neuro stuff that 3T really does.”

Coils, channels and motion compensation

The main advantage of the newest generation of 1.5T systems is 128 channels, says Winkler. Each coil is a radio antenna around the patient and “historically, there’s one for a part of the body with up to 16 coils within one antenna. Now there are 128 coils.” These very sophisticated, high-density coil sets with a total of 128 potential channels offer greater image quality. This is particularly useful in cancer screening and detecting metastases, Winkler says. “We can get unique information about multiple body parts and it’s easier to see many kinds of anatomy.”

That is becoming helpful for patients with poor renal function. Winkler says Toshiba has been working on MR angiography technologies that do not require contrast. “People who have vascular disease are the people who most need MRA but who are at the most risk from the use of contrast.” A new, safer method of performing MRA for these patients “is rapidly becoming another hot field.”

Daniel Chernoff, MD, PhD, is director of MRI services for Adirondack Radiology Associates, which has six locations in New York. The organization uses Echelon 1.5T from Hitachi Medical Systems America. Chernoff says Hitachi’s Radar technique is “very useful in imaging the patient who has difficulty remaining motionless during scanning and in reducing respiratory motion artifact in body imaging.” Radar is Hitachi’s new motion compensating image collection technique, which is based on a radial k-space data collection approach delivering reduced vulnerability to both bulk and physiological motion. Images collected with Radar are typically free from artifacts caused by breathing, gross motion and flow.

Chernoff also appreciates the broad applicability of Radar. “I use it for neuro, ortho and body imaging with complete flexibility of imaging plane.”

Regardless of special features and efforts to expand the use of MR imaging, 1.5T MRI is a competitive market. Chernoff says there is another scanner within spitting distance, another within eyesight and another at the local hospital. There’s also another at the outpatient imaging center at a hospital three miles away. “And this is a town of 30,000 [people],” he points out. Clearly, the equipment is meeting a pressing need.