Induction and repair of DNA double-strand breaks in blood lymphocytes of patients undergoing 18F-FDG PET/CT examinations

Purpose

The purpose of this study was to evaluate DNA double-strand breaks (DSBs) in blood lymphocytes of patients undergoing positron emission tomography (PET)/CT using γ-H2AX immunofluorescence microscopy and to differentiate between ¹⁸F-fluorodeoxyglucose (FDG) and CT-induced DNA lesions.

Methods

This study was approved by the local Ethics Committee and complies with Health Insurance Portability and Accountability Act (HIPAA) requirements. After written informed consent was obtained, 33 patients underwent whole-body ¹⁸F-FDG PET/CT (3?MBq/kg body weight, 170/100 reference mAs at 120?kV). The FDG PET and CT portions were performed as an initial CT immediately followed by the PET. Blood samples were obtained before, at various time points following ¹⁸F-FDG application and up to 24?h after the CT scan. Distinct foci representing DSBs were quantified in isolated lymphocytes using fluorescence microscopy after staining against the phosphorylated histone variant γ-H2AX.

Results

The DSB values at the various time points were significantly different (p?18F-FDG administration (median excess foci 0.11/cell, range 0.06–0.27/cell) and 5?min after CT (median excess foci 0.17/cell, range 0.05–0.54/cell). A significant correlation between CT-induced DSBs and dose length product was obtained (ρ?=?0.898, p?p?=?0.003) compared to pre-exposure levels.

Conclusion

PET/CT-induced DSBs can be monitored using γ-H2AX immunofluorescence microscopy. Peak values may be obtained 30?min after ¹⁸F-FDG injection and 5?min after CT. The radionuclide contributes considerably to the total DSB induction in this setting.