SPIO-enhanced magnetic resonance imaging study of placental perfusion in a rat model of intrauterine growth restriction

Objective To assess placental perfusion with magnetic resonance imaging (MRI) and superparamagnetic iron oxide (SPIO) in a rat model of intrauterine growth restriction (IUGR). Design Experimental animal study. Setting The study complied with US National Institutes of Health recommendations for animal care. Population Thirty-two rats at day 16 of gestation underwent surgical ligation of the left uterine vessel to induce IUGR. Methods Eighteen rats were examined by MRI 3 days later, after bolus injection of ferucarbotran. Main outcome measure Signal intensities were measured in the maternal left ventricle and in the placentas of the two horns. Quantitative microcirculation parameters were calculated and compared between the placentas of the two horns. Results Fifty-four kinetic curves of placental perfusion were obtained in 11 rats. The mean placental blood flow was significantly lower in the ligated horns than in the normal horns (108.1 versus 159.4 ml/minute/100 ml, p = 0.0004). The mean fractional volume of the maternal vascular placental compartment did not differ significantly between the pathological (42.8%) and normal placentas (39.2%). Conclusions Placental perfusion, including changes during experimental IUGR, can be measured in rats by using MRI with SPIO. These findings could have implications for human studies of placental microcirculation and for the management of disorders related to placental dysfunction.