Potential increase in radiation-induced DNA double strand breaks with higher doses of iodine contrast during coronary CT angiography.

PURPOSE To investigate the contrast media iodine dose-dependency of radiation-induced DNA double strand breaks (DSBs) during a coronary CT angiography (CCTA) scan. METHODS This prospective patient study was approved by the ethical committee. Between 11/2018 and 07/2019, fifty patients (31 male and 19 female, mean age 64 years) were included in the study, forty-five CCTA and five non-contrast enhanced (NCE) cardiac CT patients. A single-heartbeat scan protocol with a patient-tailored contrast media injection protocol was used, administering a patient-specific iodine dose. DNA double-strand breaks were quantified using a γH2AX foci assay on peripheral blood lymphocytes. The net amount of γH2AX/cell was normalized to the individual patient CT dose by the size-specific dose estimate (SSDE). Correlation between the administered and blood-iodine dose and the SSDE normalized amount of DNA DSBs was investigated using a Pearson correlation test. RESULTS CCTA patients were scanned with a mean CTDIvol of 10.6±5.6 mGy, corresponding to a mean SSDE of 11.3±5.3 mGy while the NCE cardiac CT patients were scanned with a mean CTDIvol of 6.00±1.8 mGy, corresponding to a mean SSDE of 6.6±2.7 mGy. The administered iodine dose ranged from 16.5 to 34.0 gI in the CCTA patients, resulting in a blood-iodine dose range from 5.1 to 15.0 gI in the exposed blood volume. A significant linear relationship (r = 0.79, p-value<0.001) was observed between the blood iodine dose and SSDE normalized radiation-induced DNA DSBs. A similar significant linear relationship (r = 0.62, p-value<0.001) was observed between the administered iodine dose and SSDE normalized radiation-induced DNA DSBs. CONCLUSIONS This study shows that contrast media iodine dose increases the level of radiation-induced DNA DSBs in peripheral blood lymphocytes in a linear dose dependent manner with CCTA. Importantly, the level of DNA DSBs can be reduced by lowering the administered iodine dose. This article is protected by copyright. All rights reserved.