Search

Objective: To quantify DNA damage in patients undergoing non-contrast and contrast-enhanced 18 F-FDG PET/CT whole body positron emission tomography/computed tomography (WB PET/CT) investigations using comet assay technique and micronucleus assay, and to study the effect of other baseline parameters of patients on DNA damage. Methodology: Eighty-four patients referred for 18 F-FDG PET/CT investigation were included in the study of which 44 patients underwent contrast-enhanced WB PET/CT and 40 patients underwent non-contrast WB PET/CT investigations. The investigations were performed on Discovery 690 PET/CT. For contrast-enhanced investigation, Omnipaque300 was injected intravenously based on the patient body weight. Absorbed dose resulting from the intravenous administration of 18 F-FDG was estimated using the ICRP 106 dose coefficients. Radiation dose from the acquisition of CT scans was estimated using CT dose index and dose-length product. Blood samples were collected from the patients for DNA damage analysis. Comet assay and MN assay was used to assess the DNA damage. The Differences in the comet TM (Tail Moment) and MNBC % in both groups were calculated. Result: The radiation dose received by the study population during 18 F-FDG WB PET/CT examination was 27.03 ± 2.33 mSv. Comet TM and percentage frequency of MNBC % was 65.22 ± 35.42 and 18.55 ± 10.14, respectively in the patients injected with contrast and 42.49 ± 28.52 and 13.76 ± 7.52 for non-contrast group. Significant increase in DNA damage was observed in the contrast group as compared to non-contrast group. Significant association was observed between patient weight, contrast volume and TM and MNBC%. Baseline parameters of the patients did not show significant correlation with TM and MNBC%. Conclusion: The patients undergoing contrast-enhanced WB PET/CT investigations have demonstrated higher DNA damage. The DNA damage was also observed to be more in heavier patients. The other baseline parameters of patients like age, sex, CBG, serum creatinine did not show any correlation with DNA damage.

PET/CT (Positron Emission Tomography/Computed Tomography) is a dual imaging modality comprising of PET and CT scanners. It finds application in diagnosis of malignancy, tumor staging, image guided therapy planning, treatment monitoring and improved localization for biopsy. With rapid increase in the use of this modality there is rising concern in relation to high radiation exposure from dual radiation modality. The extent of DNA damage during a PET/CT scan has not been reported so far. DNA double-strand break (DSB) is the most common form of DNA damage which if not adequately repaired may lead to genomic instability and cell death via generation of chromosomal aberrations or induction of apoptosis. Biological effects like DNA damage may be caused by many factors like smoking, alcohol, ultraviolet radiation, use of contrast media and radiation dose during radiological investigations. The possible factors associated with enhanced DNA damage during PET/CT procedures include radiation dose, and contrast media & administered volume. Recently there is increase in trend of performing contrast enhanced computed tomography (CECT) as an adjunct to PET for better delineation of anatomy. It has been estimated that approximately eight million litres of iodinated contrast media are administered worldwide each year. Contrast media are medical drugs used to improve the visibility of internal organs and structures in Xray based imaging techniques. They may have renal injury and many side effects ranging from itching to a lifethreatening emergency.Though the frequency of side effects has fallen significantly since the introduction of non-ionic, monomeric contrast agents, however, side effects remain an important issue. [ABSTRACT FROM AUTHOR]