Magnetic resonance and ionizing radiation: a comparative evaluation in vitro of oncogenic and genotoxic potential.

This paper describes experiments designed to investigate possible biological hazards associated with magnetic resonance (MR) imaging. Mouse C3H 10T1/2 cells were exposed to a powerful magnetic field (up to 2.7 T) for periods up to 17 hours together with pulsed field gradients and radio-frequency excitation and compared with untreated controls and cells exposed to gamma rays (0.3 to 0.4 Gy). Several biological endpoints were studied. In the case of oncogenic transformation, no significant difference could be demonstrated between controls and either the gamma-irradiated or MR-exposed cells. When mitotic cells were examined for chromosomal alterations, the frequencies of both chromosomal aberrations per cell and sister chromatid exchanges per chromosome were significantly enhanced over control levels after ionizing radiation exposures but were similar to control (or less) after MR exposures. These studies confirm the known deleterious effects of ionizing radiation (even at low doses) for chromosomal damage, if not for oncogenic transformation, yet show that MR exposures even of long duration (up to 17 hours) at high field strengths (up to 2.7 T) do not result in effects greater than 0.3 Gy of gamma rays. Negative results do not conclusively rule out a health risk; however, the data clearly mitigate against an association between exposure to MR imaging modalities and both carcinogenic and genotoxic effects.