“Everyone is keeping up with the Joneses, and there are more Joneses than ever.” This statement from art critic Jerry Saltz refers to the buying habits of a public hungry for trendy art. However, it could as easily apply to MRI technology, where the strength of the magnet—measured in units called Tesla, or T—makes all the difference in how accurate and readable the resulting scans are. To attract patient referrals, imaging centers are eager to keep up with, or even outdo, each other.
Several years ago, the manager of an outpatient diagnostic imaging center in Tacoma, WA, wrote:
… as MRI technology evolves, 3T MRI studies (as opposed to 1.5T) are increasingly common in the clinical setting. The higher field strength of 3T MRI results in an increase in signal-to-noise ratio, spatial resolution, and speed, all of which may provide substantial benefits.
With the exception of academic research centers, 1.5 Tesla (1.5T) magnets were pretty much all that has been available in community imaging centers and hospitals until fairly recently. To obtain as high qualify prostate images as possible, many centers used an endorectal coil (antenna inserted into the rectum) encased in a fluid-expandable balloon. This protocol came with two downsides: 1) when fully inflated to almost the size of a Coke can, the endorectal coil proved quite uncomfortable for most patients, and 2) this size placed pressure on the prostate gland that created a distorted image of the true anatomy. However, with the introduction of 3T magnets, external body coils, and improved sequencing, it is now possible to produce images using different parameters, and correlate the results to gain visual information on suspicious areas in the gland.
This has created competition for patients that spurs hospitals and imaging centers to consider investing in 3T magnets, which are twice as powerful as conventional 1.5T equipment, and 10-15 times as powerful as “open” MRI scanners which have a much lower magnetic field. According to president Tobias Gilk of Mednovus, “Imaging providers are saying ‘Hey, the guys across town have a 1.5-tesla MRI. How do we differentiate ourselves? How do we offer something to this market that the other providers can’t or don’t?’ ” Acquiring a 3T magnet is an expensive proposition with a price tag upwards of $2.5 million. Administrators must consider how many patients are likely to require very high resolution scans. On the one hand, centers with 3T magnets are able to put them to work in areas besides prostate imaging, such as detecting and diagnosing different cancers, neurological conditions, and cardiovascular disorders. On the other hand, since many diseases are associated with aging, older people with earlier model metal orthopedic implants may not be able to undergo 3T detection if their implants are not FDA approved for 3T MRI scans.
Nonetheless, as research sheds more light on conditions like Alzheimer’s disease, Parkinson’s disease and multiple sclerosis, demand for more magnet “horsepower” is pushing MRI to new limits. In fact, 7T magnets that are 140,000 times stronger than the earth’s magnetic field are now being used in medical research because they allow unprecedented imaging detail of the brain and other organs. These magnets weigh 40 tons with about 10 times more wire and can store about 5 times more energy than a 3T magnet.[i] As you can imagine, the cost is likewise heftier.
Whether such powerful technology will become the norm remains to be seen. For now, improvements in 3T magnets are making it possible to reduce the scanning noise level, to reduce the scan time thanks to faster image capture, and to obtain images that synch with patient motion such as breathing in a way that is similar to “freezing” the image in order to achieve the clarity that comes with stillness. At our Center, we are always working to bring state-of-the-art MRI detection to you, our patients, for top-shelf imaging results.