Biological dosimetry of magnetic resonance imaging

Purpose: To check the bioeffects of the components of magnetic resonance imaging (MRI). MRI is based on an assumedly harmless interaction between certain nuclei in the body when placed in a strong magnetic field and radio wave fields. There are three key factors actuating on the examining body: a powerful static magnetic field (SMF), magnetic gradient fields (MGFs), and pulsed radiofrequency (RF) radiation. Materials and Methods: In vitro cells (L-132 cells) were used as biosensors, and different cellular compounds were used as biomarkers (heat shock proteins [HSPs] and their messenger ribonucleic acids [mRNAs], calcium, and adenosine-3',5'-cyclic monophosphate [cAMP]). The biosensors were placed in the bore of a 1.5-T MRI machine and the different electromagnetic fields were operated. Results: HSPs and their mRNAs and cAMP did not respond to SMF, MGFs. or RF radiation. RF radiation increased cytosolic calcium concentration (18%, P < 0.05). Conclusion: Although MRI procedures do not induce any cellular stress response, it may cause an unfathomable calcium increase in vitro. Although the in vitro experimental conditions are not totally comparable to clinical situations, the usefulness of the in vivo biological dosimetry, circulating leukocytes as biosensors, and HSPs and/or calcium as biomarkers is suggested. (C) 2002 Wiley-Liss, Inc.