Gadolinium chelate contrast material in pregnancy: Fetal biodistribution in the nonhuman primate

Purpose: To determine the extent to which gadolinium chelate is found in nonhuman primate fetal tissues and amniotic fluid at 19-45 hours after intravenous injection of a weight-appropriate maternal dose of the contrast agent gadoteridol. Materials and Methods: Gravid Japanese macaques (n = 14) were maintained as approved by the institutional animal care and utilization committee. In the 3^rd trimester of pregnancy, the macaques were injected with gadoteridol (0.1 mmol per kilogram of maternal weight). Fetuses were delivered by means of cesarean section within 24 hours of maternal injection (range, 19-21 hours; n = 11) or 45 hours after injection (n = 3). Gadolinium chelate levels in the placenta, fetal tissues, and amniotic fluid were obtained by using inductively coupled plasma mass spectrometry. The Wilcoxon rank sum test was used for quantitative comparisons. Results: Gadoteridol was present in the fetoplacental circulation at much lower quantities than in the mother. At both time points, the distribution of gadolinium chelate in the fetus was comparable to that expected in an adult. The highest concentration of the injected dose (ID) was found in the fetal kidney (0.0161% ID per gram in the 19-21-hour group). The majority of the in utero gadolinium chelate was found in the amniotic fluid and the placenta (mean, 0.1361% ID per organ ± 0.076 [standard deviation] and 0.0939% ID per organ ± 0.0494, respectively). Data acquired 45 hours after injection showed a significant decrease in the gadolinium chelate concentration in amniotic fluid compared with that in the 19-21-hour group (from 0.0017% to 0.0007% ID per gram; P = .01). Conclusion: Amounts of gadolinium chelate in the fetal tissues and amniotic fluid were minimal compared with the maternal ID. This may impact future clinical studies on the safety of gadolinium contrast agent use in pregnancy.