This raises the question as to whether the observed effect is based on the dosage used. "There is probably a connection between the energy absorbed by the patient”, replies Professor Lancellotti. “We showed that there is a linear relationship between the energy absorbed or delivered to the patient and the persistence of a high level of gamma-H2AX measured in the circulating T lymphocytes one month after the exam. It must be understood that if longer-lasting examinations are conducted, this could have an impact on the energy produced, released and then absorbed, theoretically leading to more lesions".

"This depends not only on the timescale involved, but also on the type of sequence (2) or excitation. The correlation observed between the quantity of energy and the lesions observed after one month exist, but a greater number of subjects would be required in order for us to be absolutely certain", adds Alain Nchimi.

Other observed phenomena also interest Patrizio Lancellotti: "We noticed that the examination induced temporary inflammation, characterised by a small decrease in the number of natural killer lymphocytes and an activation of neutrophils and monocytes. The positive aspect in all this is that there was no activation of platelets and therefore no prothrombotic (favouring thrombosis) phenomenon linked to the examination".

Not as harmless as previously thought

These results lead to the conclusion that this examination is perhaps not so risk-free as generally thought: "In our work, we showed that in half of the subjects, there was an increase in these alterations and which was more marked after one month of follow up. On the other hand, the reassuring thing is that, after one year, there was a complete normalization. It is clear that there is a phenomenon and that it needs to be confirmed", considers the cardiologist.

He adds, “The question we are asking, is whether the patient is more likely to develop DNA lesions linked to magnetic resonance, which, in this case, was conducted without injection of gadolinium. Use of the latter provides a better visualisation of cardiac structure, but it is also potentially toxic and could therefore accentuate the deleterious phenomena observed. This is really something new because most of the data previously obtained in vivo involved an injection of gadolinium: in this case, you cannot distinguish between the examination itself and the contrast agent used".

Some other questions raised by this study are: will the modifications reoccur if the examination is repeated and what are the consequences of these modifications in the short and long term? "The most important thing from my point of view”, points out Patrizio Lancellotti, “is to know what will happen if we conduct several examinations. Let’s imagine that I do a chest scan, a CMR and a PET scan in order to establish a diagnosis: what impact will this have on lymphocyte DNA? What has been recommended - and is in fact more of a suggestion – is to at least avoid conducting several CMR examinations, perhaps within the same month, on individuals that are considered healthy as we do not yet know the consequences of this".

This warning is all the more valid if contrast agents are used. "Prudence and similar restrictions already apply to examinations which use X-rays and nuclear imaging”, warn the GIGA researchers. Furthermore, what worries them, independently of the results, is the fact that the study involved young men whereas the mechanisms for DNA repair are less efficient in elderly...

How can the current doubt be confirmed?

The work of the team from GIGA therefore does not stop here. The risk needs to be confirmed and clarified by means of in vitro and in vivo tests on animals (mice). For the in vitro section, they plan to conduct several tests directly on human blood in order to observe the effect of this non-ionizing radiation on lymphocytes. "By keeping these lymphocytes in culture for several days after exposure to a magnetic field, we will be able to study the DNA repair mechanisms and to see whether or not DNA double-strand breaks are indeed induced by the magnetic field in question", explains Cécile Oury, who speaks very highly of the working environment offered by GIGA and the University Hospital of Liege: "The environment is ideal, it makes this study possible thanks to direct collaboration between cardiologists, radiologists and biologists (molecular and cellular)”.

2. An MRI sequence includes all the parameters which define magnetic field pulses and the characteristics of measurements made by magnetic resonance imaging.