Three-Dimensional Power Doppler Evaluation of Cerebral Vascular Blood Flow: A Novel Tool in the Assessment of Fetal Growth Restriction.

OBJECTIVES: To determine whether fetuses with fetal growth restriction (FGR) are more likely to have abnormal cerebral vascular flow patterns compared to fetuses who are appropriate for gestational age (AGA) when quantified by using 3-dimensional (3D) power Doppler ultrasound.

METHODS: We conducted a prospective cohort study of singleton gestations presenting for growth ultrasound examination between 24 and 36 weeks' gestation. Patients with FGR (estimated fetal weight < 10th percentile) were enrolled and matched 1:1 for gestational age (±7 days) with AGA fetuses. A standardized 3D power Doppler image of the middle cerebral artery territory was obtained from each patient. The vascularization index (VI), flow index (FI), and vascularization-flow index (VFI) were calculated by the Virtual Organ computer-aided analysis technique (GE Healthcare, Milwaukee, WI). These indices were compared between FGR and AGA fetuses and correlated with 2-dimensional Doppler parameters. Neonatal outcomes were also compared with respect to the 3D parameters.

RESULTS: Of 306 patients, there were 151 cases of FGR. There was no difference in the VI (6.0 versus 5.7; P = .65) or VFI (2.0 versus 1.8; P = .31) between the groups; however, the FI was significantly higher in FGR fetuses compared to AGA controls (33.9 versus 32.3; P = .009). There was a weak, but significant, negative correlation between the FI and both the middle cerebral artery pulsatility index (r = -0.34; P < .001) and cerebroplacental ratio (r = -0.29; P < .001). Within the FGR group, there was no difference in any of the 3D vascular indices with regard to neonatal outcomes.

CONCLUSIONS: Three-dimensional power Doppler measurement of cerebral blood flow, but not the vascularization pattern, is significantly altered in FGR. This measurement may play a future role in distinguishing pathologic FGR from constitutionally small growth.