When used in low concentrations, nonionic, water-soluble contrast agents do not adversely affect colon cells in pre-term infants, according to Austrian radiologists. While contrast media containing iopamidol, a low-osmolar compound, is commonly used for evaluating the colon in pre-term infants, data on the safety of this practice is scarce, said Dr. Stefan Puig from the University of Vienna.
"Our purpose was to evaluate the effects of this contrast media on the viability of fetal colon cells," Puig told attendees at the American Roentgen Ray Society meeting in May. The study sample consisted of colon fibroblasts from a 13-week-old fetus, a 22-week-old fetus, and a seven-year-old child.
The cells were grown according to the American Type Culture Collection protocols. The various components of the contrast agent Gastromiro, including iopamidol, were diluted with the culture medium. Gerot of Vienna, the manufacturer of Gastromiro, funded this study, Puig said.
Measurements of viability were taken using MTT stain, 51-chromo release, and a plating efficiency test. According to the results, as the concentration of the iopamidol and the duration of incubation time increased, the colon cells became less viable. The reduction rate was between 25% and 100% after 24 hours, Puig said. A high concentration of iopamidol also suppressed new cell colony formation, according to the results of the plating efficiency test.
However, there was no significant difference between the fetal cells and those of the seven-year-old child, Puig said. In both cases, the MTT stain showed that a high concentration of the contrast agent would have a toxic affect on the cells.
The group concluded that any contrast media that contain iopamidol should be diluted at a ratio of less than 1:3 when being used for a colon examination in a pre-term infant.
Other well-established contrast agents for studying the fetal colon include meglumine/Na diatrizoate and meglumine/CA metrizoate. According to a researcher from the Institute of Surgical Research in Oslo, Norway, up to six times more chromium-51 was released from cultured endothelial cells when exposed to these agents. In their study, iopamidol gave a chromium-51 release rate that was equal or lower than that of a 0.9% saline solution (Radiology, June 1983, Vol. 147:3, pp.681-684).
By Shalmali Pal
AuntMinnie.com staff writer
May 18, 2000
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