CT检查中碘对比剂对DNA损伤的初步分析

Research on the effect of iodinate contrast agent on the DNA radiation damage at CT

目的 评估CT检查中碘对比剂对人外周血单个核细胞DNA双链的影响。方法 采集2016年2至5月期间36名健康志愿者的外周静脉血（16 ml/人），将其平均分成4组8管，每组其中1管加入25 μl对比剂作为对照管。4组样本随机标记为A-D组，其中B、C、D组在相同CT辐射条件下辐射1、2、3次。实验室离心获取外周血淋巴细胞，荧光显微镜下计数每个淋巴细胞中γH2AX焦点数量。结果 A组中单纯加入碘对比剂后γH2AX焦点比基础焦点数量增加约82.9%[（0.064±0.025）和（0.035±0.010 ）焦点/细胞）]；随着CT辐射剂量增加，B-D组焦点损伤数量亦增加，且同组中加入对比剂的样本比单纯辐射损伤更多[B组：（1.217±0.158）和（0.774±0.258）焦点/细胞；C组：（2.128±0.185）和（1.569±0.201）焦点/细胞；D组：（3.812±0.490）和（2.938±0.480）焦点/细胞]；在一定范围内，CT辐射剂量越大，碘对比剂放大辐射损伤效应越明显[B-D组两管焦点差值分别为（0.489±0.323）、（0.549±0.278）、（0.692±0.462）焦点/细胞]。结论 碘对比剂本身可能引起DNA双链断裂，在CT检查中碘对比剂的存在能够放大DNA损伤。

Objective To evaluate the effect of iodinate contrast agent （ICA） on the formation of DNA double-stand breaks （DSBs） in human peripheral blood lymphocytes during computed tomography （CT） examinations. Methods Peripheral venous blood （16 ml/person） of 36 volunteers were collected during the period of February to May 2016. Each blood sample was divided into 8 tubes and 4 groups on average, which were marked as groups of A, B, C, D randomly. 25 μl ICA was respectively added into one tube of each group and the groups of B, C, D accepted the same CT scan for once,twice and three times. The lymphoeytes in these blood samples were separated by using density-gradient centrifugation, fixed and immunostained with γH2AX antibody. The average number of phosphorylated histone H2AX （γH2AX） loci per lymphocyte was counted under a fluorescence microscopy. Results The numbers of γH2AX loci were increased approximately 82. 9% （ （0.064 ± 0. 025 ） vs （0. 035 ± 0. 010） foci/cell） if ICA was simply added into the blood. With the increase of CT radiation, the foci numbers of the groups of B, C, D would increase and the samples eontaining ICA could have a more amount of foei numbers than those without ICA （B：（1.217 ±0. 158） vs （0. 774 ±0. 258） ;C：（2. 128±0. 185） vs （1. 569 ±0. 201） ;D：（3. 812 ±0. 490） vs （2.938 ± 0.480） loci/cell）. The more radiation it had, the more significant the difference of loci numbers would be （ （0. 489±0. 323 ）, （0. 549 ± 0. 278 ） , （ 0. 692 ±0.462 ） loci/cell）. Conclusion The ICA itself can lead to an increase of the DSBs level and the application of ICA can amplify the DNA damage as assessed with γH2AX loci formation during diagnostic X-ray orocedures.