Double-strand breaks in lymphocyte DNA of humans exposed to [(18)F]fluorodeoxyglucose and the static magnetic field in PET/MRI

BACKGROUND: Given the increasing clinical use of PET/MRI, potential risks to patients from simultaneous exposure to ionising radiation and (electro)magnetic fields should be thoroughly investigated as a precaution. With this aim, the genotoxic potential of 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG) and a strong static magnetic field (SMF) were evaluated both in isolation and in combination using the γH2AX assay detecting double-strand breaks in lymphocyte DNA. METHODS: Thirty-two healthy young volunteers allocated to three study arms were exposed to [(18)F]FDG alone, to a 3-T SMF alone or to both combined over 60 min at a PET/CT or a PET/MRI system. Blood samples taken after in vivo exposure were incubated up to 60 min to extend the irradiation of blood by residual [(18)F]FDG within the samples and the time to monitor the γH2AX response. Absorbed doses to lymphocytes delivered in vivo and in vitro were estimated individually for each volunteer exposed to [(18)F]FDG. γH2AX foci were scored automatically by immunofluorescence microscopy. RESULTS: Absorbed doses to lymphocytes exposed over 60 to 120 min to [(18)F]FDG varied between 1.5 and 3.3 mGy. In this time interval, the radiotracer caused a significant median relative increase of 28% in the rate of lymphocytes with at least one γH2AX focus relative to the background rate (p = 0.01), but not the SMF alone (p = 0.47). Simultaneous application of both agents did not result in a significant synergistic or antagonistic outcome (p = 0.91). CONCLUSION: There is no evidence of a synergism between [(18)F]FDG and the SMF that may be of relevance for risk assessment of PET/MRI.