In the future, MRIs can avoid harmful radiation in orthodontics

30.01.2019 | The European Federation of Orthodontics FEO honors this research work with the international FEO Award

In collaboration with the orthodontist Dr. Andreas Detterbeck, the orthodontics department at the Universitätsklinikum Erlangen and the University of Bonn, researchers at the Fraunhofer Institute for Integrated Circuits IIS have succeeded in applying magnetic resonance imaging, MRI, in orthodontics. In recognition of this scientific achievement, the European Federation of Orthodontics FEO presented the researchers with the 2018 FEO Award at the end of that year.

Comprising members of the Magnetic Resonance and X-Ray department in Würzburg and the Fraunhofer Application Center for CT in Metrology in Deggendorf, the Fraunhofer research team and its collaboration partners tested if and how orthodontic examinations could be performed without ionizing X-radiation. As part of their study using pig heads, they were able to provide a methodology for proving the general suitability of magnetic resonance imaging for orthodontic purposes. In many areas, it appears that MRIs provide images that are just as good as the 3D X-ray images in use today.

We spoke with Dr. Daniel Haddad, a researcher in the Magnetic Resonance and X-Ray department:

© Fraunhofer IIS
The study shows there to be no significant differences between magnetic resonance imaging (MRI) without X-rays and computer tomography (CT).

Dr. Haddad, what was the initial idea behind developing this technology? The average person doesn’t really see a difference between X-ray and MRI images.

The main group of patients for orthodontic tests is made up of children and adolescents. Compared to adults, this group is more susceptible to the risk of damage caused by ionizing radiation, as shown by the Brody study from 2007. The advantages of MRI techniques are that they provide good contrast without using any ionizing radiation. An Australian study from 2013 reports that for the group studied, the general risk of developing cancer was 24 percent higher for those people who had a CT scan in the years leading up to the illness than those who had not. So it would be great if in the future we could use alternative examination options for orthodontics that would completely avoid damage caused by radiation.

What has to happen before the technique can be applied for widespread use in orthodontics or even in dentistry generally?

There are various points to consider:
First it’s crucial to significantly raise acceptance for the use of MRIs as a replacement for current techniques that use ionizing radiation. In particular, this entails testing all the sample applications individually to determine the ones in which magnetic resonance imaging is equally good or even better than current methods for diagnosis or treatment. More specifically, it must be shown for each application that the data an MRI offers orthodontists or dentists is at least as conclusive as that currently gained through other methods. It’s also necessary to train physicians properly since MR images can look completely different from the likes or X-rays or CT images delivering the same degree of information.

And second, there is much development work still to be done. This primarily concerns cases in which an MRI can provide as much or even more data than current methods. What we need are MR experiments that are tailored to each point of investigation, but that are also easy to perform, user-friendly and require little training. This may also involve ensuring that when processing the MRI data, image contrast and the way the images look should be similar to those of images generated with current methods.

In addition, MRI machines currently in use would have to be developed and approved for widespread use in orthodontics. Up to now, only typical clinical MRI machines have been used, ones equipped with the necessary detectors, for instance head and jaw coils. This can remain the case in the future and is certainly easy to accomplish in a hospital or university clinic setting, where orthodontics and radiology are on the same site or even same building. Most cases seen at local orthodontic practices would require a referral to a radiologist.

Dr. Daniel Haddad Fraunhofer IIS
© Fraunhofer IIS
Dr. Daniel Haddad

Do you expect MRIs to one day replace X-rays entirely?

No, certainly not any time soon. At the moment, I’m more inclined to expect that the MRI be rolled out step by step to show where it can sensibly replace existing methods and that it can be used in exactly the same environment. And despite the advantages of the MRI, the necessary technical advancement and acceptance mean this will certainly take some time. In addition, there are sure to be examples of applications for which the current methods are indeed superior and should continue to be used. The only alternative to this I can imagine would be in new research findings that expand current MRI applications or combine them with other imaging techniques with a view to reducing the overall use of ionizing radiation methods.

Studies referenced:

[Brody 2007]
Alan S. Brody, MD, Donald P. Frush, MD, Walter Huda, PhD, Robert L. Brent, MD, PhD, and the Section on Radiology: “Radiation Risk to Children From Computed Tomography”;
PEDIATRICS Volume 120, Number 3, September 2007

[Mathews 2013]
JD Mathews, AV Forsythe, Z Brady, MW Butler, SK Goergen, GB Byrnes, GG Giles, AB Wallace, PR Anderson, TA Guiver, P McGale, TM Cain, JG Dowty, AC Bickerstaffe, SC Darby: “Cancer risk in 680 000 people exposed to computed tomography scans in childhood or adolescence: data linkage study of 11 million Australians”; BMJ 2013;346:f2360