Impact of in Vivo high-field-strength and ultra-high-field- strength mr imaging on DNA double-strand-break formation in human lymphocytes

Abstract

Purpose: To determine the impact of different magnetic field strengths (1, 1.5, 3, and 7 T) and the effect of contrast agent on DNA double-strand-break (DSB) formation in patients undergoing magnetic resonance (MR) imaging. Materials and Methods: This in vivo study was approved by the local ethics committee, and written informed consent was obtained from each patient. To analyze the level of DNA DSBs, peripheral blood mononuclear cells were isolated from blood samples drawn directly before, as well as 5 minutes and 30 minutes after MR imaging examination. After performing gH2AX immunofluorescence staining, DSBs were quantified with automated digital microscopy. MR group consisted of 43 patients (22 women, 21 men; mean age, 46.1 years; range, 20-77 years) and was further subdivided according to the applied field strength and administration of contrast agent. Additionally, 10 patients undergoing either unenhanced or contrast material-enhanced computed tomography (CT) served as positive control subjects. Statistical analysis was performed with Friedman test. Results: Whereas DSBs in lymphocytes increased after CT exposure (before MR imaging: 0.14 foci per cell 6 0.05; 5 minutes after: 0.26 foci per cell 6 0.07; 30 minutes after: 0.24 foci per cell 6 0.07; P ? .05), no alterations were observed in patients examined with MR imaging (before MR imaging: 0.13 foci per cell 6 0.02; 5 minutes after: 0.12 foci per cell 6 0.02; 30 minutes after: 0.11 foci per cell 6 0.02; P . .05). Differentiated analysis of MR imaging subgroups again revealed no significant changes in gH2AX level. Conclusion: Analysis of gH2AX foci showed no evidence of DSB induction after MR examination, independent of the applied field strength and administration of gadolinium-based contrast agent.