Radiology: Volume 253: Number 3—December 2009
Saskia Grudzenski, Dipl Biol Michael A. Kuefner, MD Martina B. Heckmann, MD Michael Uder, MD Markus Lobrich, PhD
Purpose: To assess the effect of iodinated contrast medium (CM) on the induction and repair of DNA double-strand breaks (DSBs) in peripheral blood lymphocytes after computed tomographic (CT) examinations.
Materials and Methods: This prospective study was approved by the institutional ethics committee; written informed patient consent was obtained from 37 patients. Venous blood samples were taken from patients before and at 30 minutes, 1 hour, 2.5 hours, and 5 hours after performing CT with (n = 18) or without (n = 19) intravenous administration of CM (iopro-mide or iomeprol). DSBs were assessed in lymphocytes by enumerating 7H2AX foci. DSB levels after CT were com¬pared with those obtained after in vitro irradiation. Cell culture experiments with peripheral lymphocytes and fibroblasts were performed with iopromide, iomeprol, or the control substance mannitol added before or immedi¬ately after x- or 7-ray irradiation. DSBs were assessed at 5 minutes, 30 minutes, 2.5 hours, and 5 hours after irradiation. Data were analyzed by using linear regression and the one-tailed Welch and paired sample t tests.
Results: The presence of CM during CT increases DSB levels in peripheral lymphocytes by approximately 30%. Cell culture experiments confirmed this effect and further showed that CM administered prior to x-ray irradiation increases the initial DSB yield but has no effect if added after irradiation or when 7-rays are used instead of x-rays.
Conclusion: The highly sensitive 7H2AX foci assay shows that CM-enhanced radiation damage incurred in peripheral lym¬phocytes during CT. However, it is unknown whether long-term bioeffects of low-dose ionizing radiation from CT examinations, such as cancer, are increased by using CM