Measurement of placental perfusion by dynamic contrast-enhanced MRI at 4.7 T

The purposes of this study were to develop quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) at 4.7 T for perfusion measurement and to evaluate the ability of this technique to distinguish between low and normal levels of placental perfusion in a controlled rat model.

This study was approved by the animal care committee. Poor placental perfusion in the left uterine horn was achieved by ligation of the left uterine vascular pedicle on the 17th embryonic day in 12 pregnant rats. High-temporal resolution DCE-MRI (<1 second) was performed on the 19th embryonic day. Single-compartment analysis was used to calculate placental blood flow (F), volume fraction (Vb), and time delay (Dt) for each placenta and its 2 layers in both uterine horns. Mixed regression analysis was used to compare parameters between the ligated and nonligated horn and between placental layers.

We examined 53 placentas: 11 on the ligated side and 42 on the control side. On the control side, the mean (SD) values were 115 (72) mL/min per 100 mL for F, 38.6% (11.7%) for Vb, and 5.5 (5.3) seconds for Dt. Placental blood flow was significantly lower on the ligated side (66 [30] mL/min per 100 mL; P = 0.001).Placental blood flow and Vb were significantly higher, whereas Dt was significantly lower in the inner layer than in the outer layer in both horns (P=0.0001).

Quantitative analyses of perfusion are feasible with DCE-MRI at 4.7 T.Dynamic contrast-enhanced magnetic resonance imaging can differentiate between low and normal levels of placental perfusion in a rat model. Dynamic contrast-enhanced magnetic resonance imaging at 4.7 T is a promising preclinical tool for quantifying and monitoring microvascularization.