Tattoos are increasingly popular. Every eighth person in Germany has already felt the sting of a tattoo needle. Yet, examining tattooed people via magnetic resonance imaging (MRI) could possibly be risky. The first prospective study with statistically verifiable numbers is now presenting by a research team led by Nikolaus Weiskopf in the prestigious New England Journal of Medicine.
Sciences in Leipzig
According to Weiskopf, director at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig (MPI CBS), “the most important questions for us were: Can we conduct our studies with tattooed subjects without hesitation? What restrictions may exist? At the Wellcome Centre for Human Neuroimaging, part of Queen Square Institute of Neurology at University College in London, where I started the study in 2011, there were increasing numbers of volunteers with tattoos. At the time, there simply was not enough data to determine the likelihood of tattoo-related side effects arising from MRI examinations.”
His former colleague in London, Martina Callaghan, completed the study after Weiskopf left London to become the director at the MPI CBS in Leipzig. therefore “Based on our investigations; we can now state, on the basis of meaningful numbers; that if a tattooed individual is scanne under the conditions teste in the study; the risk of side effects is very small,” the physicist explains.
Millions of people with tattoos are scanning every year in hospitals and research facilities without any side effects. Until now, there has not been a systematic prospective study on how safe it is to scan tattooed patients in an MRI scanner. Reports of adverse reactions are usually based on individual cases and describe two reactions. It is possible that the pigments in tattoos can interact with the static magnetic field of the scanner if the ink contains ferrous particles. The strong magnetic fields involved in the procedure can interact with these small particles; which in turn can lead to a pulling sensation on the tattooed skin.
However, another potential interaction may represent a far greater risk; according to the researchers. Many color pigments are conductive. This is an issue because in MR imaging uses high-frequency magnetic fields to generate the images by effectively labeling protons.
similarly sized as tattoos
“High-frequency fields usually have a frequency of a few hundred megahertz. That happens to correspond to the resonance lengths of conductive structures similarly sized as tattoos. In this case, the tattoo may absorb much of the energy of the high-frequency field; which would normally be spread out more widely. The tattoo then heats up. In the worst case, this can lead to burns,” says Nikolaus Weiskopf.
Together with his colleagues at University College in London, he examined 330 study participants before and after MRI scans and tested a total of 932 tattoos. The team systematically collecting information about participants’ tattoos—how big they are, where they are locating, and what colors are using. Patient countries of origin were in Europe, America, Asia, Africa and Australia. The majority of the tattoos were black ink, but many colors are also register.