Researchers at the Ohio State University Wexner Medical Center are using a new low-field MRI system that may expand the capabilities of MRI for patients with implanted devices, patients who require lung imaging, and obese patients. The system, which was developed in a collaboration between Siemens and Ohio State, has a magnetic field strength of 0.55 Tesla, which is low when compared with the 1.5 or 3.0 Tesla systems that are typically used. The low field strength increases the potential of the system for lung imaging, which could help patients to avoid the radiation associated with repeated X-rays, and for imaging in situations where the implanted pacemakers or defibrillators present are not safe under magnetic resonance.
MRI systems are a cornerstone in medical imaging, but they have their limitations. The small tube through which the patient slides can be claustrophobic, and many patients with obesity may not fit inside the device. The magnetic field also means that patients with pacemakers and other implants may not be suitable candidates for imaging, either due to safety concerns, or because the metal within the implants can distort the image.
“Many of our patients have pacemakers or defibrillators and while many of those devices are now safe for MR scanning, the metal in them can distort the magnetic field and corrupt the image quality,” said Orlando Simonetti, a researcher involved in the study. “We were looking for ways to improve the quality of images in these patients, and lower magnetic field strength could offer an advantage. The problem with low field MRI is that there is less signal to work with, and we needed to find ways to boost that signal.”
Another issue with MRI is that it is limited in its ability to image the lungs, at least at high field strengths, as the air in the lungs interferes with the signal. However, a lower strength system may allow for better lung imaging, which could help patients who require routine lung imaging to avoid the radiation associated with X-rays.
“The doses of radiation accumulate over time and can be harmful, especially to children who are still growing,” said Simonetti. “It may be possible to perform MRI-guided cardiology procedures safely at low field using standard catheters and guidewires; this will be safer for anyone who has to have repeated heart catheterizations and other procedures.”
To address these issues, these researchers have created the 0.55T MAGENTOM Free.Max. The scanner boasts an 80 cm opening, which makes it less claustrophobic and more accessible to patients with obesity. The low field strength may also allow clinicians to conduct imaging procedures more easily on patients with metal implants.
“There’s no doubt in my mind that low-field MRI will play an important role in the future and will become more mainstream,” said Simonetti. “Going to lower field can reduce the cost of MRI systems and installation considerably, and with modern techniques for scanning and image processing, we can overcome the inherent loss of signal.”
Here’s a video Ohio State released about this research: