Clinical usefulness of a MRI contrast medium (Gd-DTPA) and its effect on SCE frequency in lymphocytic chromosomes.

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Dimeglumine gadopentetate (Magnevist (〕SY.encircledR.〔)) is only a contrast agent in MRI, commercialized so far in Japan, and has a relatively high osmolality, that is, 1940 mOsm/kg water in clinically used solution. The agent contains of gadolinium having seven unpaired electrons in 4f orbital. The large number of unpaired electrons in 4f is responsible for a strong magnetic moment and paramagnetism of gadolinium which produces a marked shortening of Tl of protons of hydrogens of water. The shortening of Tl is causative of contrast enhancement in Tl-weighted MR imaging. Neutral gadolinium complexes such as gadodiamide and gadoteridol have been introduced into the clinical trial in Japan. The clinical usefulness and saftey of those contrast agents have been proven by various investigators, including ones in the present study.Effects of a strong magnetic field and/or radiofrequency exposure, in addition to Gd-DTPA, on sister chromatid exchange (SCE) frequency in peripheral lymphocytes were investigated in order to detect subtle side-effect in the use of MRI contrast media. At the level of concentration of Gd-DTPA in the clinical use, the contrast medium did not affect SCE frequency. As the concentration of Gd-DTPA rose up to the level of approximately 100 times over the clinical use, the frequency of SCE increased. A strong magnetic force and RF exposure also induced a increase of SCE frequency significantly.