DNA damage during chest CT exams linked to intravenous iodinated contrast: study

脱氧核糖核酸损伤在胸口CT检查期间与静脉内碘化的对比连接了: 研究

Sean Ruck, Contributing Editor | March 06, 2015
From the March 2015 issue of HealthCare Business News magazine

Intravenous iodinated contrast used during chest CT exams has been shown to increase DNA damage from radiation, according to a study recently published in the Journal Radiology in early February. “Because of X-ray exposure, the risk of developing cancer is increased as a result of additional DNA damage, primarily in the form of DNA double-strand breaks,” wrote the study’s authors.

Risks from iodinated contrast agents have been well-studied previously, they noted. But these were considered to be mostly in the form of kidney damage and cytotoxic — the impact on DNA was little understood. To determine its effects, the researchers zeroed in on the development of doublestrand breaks in DNA in those who underwent chest CT scans.

For the study, 245 patients (96 women and 149 men) were recruited from December 2009 to October 2011. Of the total, 66 underwent CT with no contrast. The other 179 had exams with contrast material — an intravenous administration of an average of 18.651 mg of iodine per patient.

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To determine possible DNA damage, the average number of phosphorylated histone HSAZ (yH2AX) foci lymphocyte was followed with fluorescence microscopy. CT scans elevated yH2AX foci levels in both contrast and non-contrast groups but for those who had been given contrast the levels rose by a significantly larger amount, approximately 107 percent, a sign of increased DNA radiation damage.

Their findings, wrote the researchers, imply two salient points: that the dose-length product with CT does not properly measure the potential risk of X-ray radiation damage unless contrast’s impact is taken into account. This is of particular import when exams are repeated, during follow-up, for example, suggesting the use of iodinated contrast agents should be weighed even more carefully.

HCBN went to editorial advisory board member and professor of radiology at University of Pennsylvania, Abass Alavi, to get his thoughts on the report. Alavi is a pioneer in molecular imaging and one of the key individuals behind the introduction of F18-Fluorodeoxyglucose (FDG) for use with positron emission tomography.

“Over the past two decades, it’s become increasingly apparent that contrast agents may not add more information than what we can gain these days from non-enhanced FDG-PET/CT. The information provided by administering contrast agents is very limited in nature and only relates to the vasculature of the lesion which is proven to reveal indirect evidence for disease activity” Alavi says.

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