(697) Longitudinal Placental Perfusion in Normal and Hypertensive Pregnancies using pseudo-Continuous Arterial Spin Labeled MRI

Perfusion may be a sensitive biomarker for in vivo assessment of normal and abnormal placental function. We sought to evaluate longitudinal placental perfusion using pseudo-continuous arterial spin labeled (pCASL) MRI in normal pregnancies and in pregnancies affected by chronic hypertension (cHTN), who are at the greatest risk for placental-mediated conditions of preeclampsia and fetal growth restriction.

Study Design: Eight normal and 17 pregnant women with cHTN on antihypertensive therapy were scanned on a Phillips 3T Ingenia MRI using pCASL at 16-20 and 24-28 weeks of gestational age. pCASL-MRI including perfusion quantification was acquired in less than 6 minutes. Mean placental blood flow (PBF) comparisons between gestational ages were performed using paired Wilcoxon tests, and comparisons between normal and cHTN groups were performed using unpaired Wilcoxon tests.

Results: Mean PBF was 114.5±43.2 and 69.0±18.3 mL/100g/min at 16-20 and 24-28 weeks and 79.5±30.8 and 71.5±28.2 mL/100g/min in normal and cHTN groups respectively. There was a significant decrease in perfusion observed between the first and second scans in normal pregnant women (Figure 1, P=0.015) which was not observed in those with cHTN (P=0.496). Perfusion significantly decreased at both time points in the three pregnant women with cHTN who went on to have infants that were small for gestational age versus those who did not (Figure 2A, 43.7±11.8 and 41.2±12.2 versus 83.6±31.9 and 72.2±27.8 mL/100g/min, P=0.023 and 0.044 respectively).

Conclusion: Placental perfusion is altered in women with cHTN, furthermore so in women with FGR.  Placental perfusion in the second trimester declined in normal pregnant women whereas it remained relatively unchanged in those with cHTN, consistent with alteration due to vascular disease pathology. Perfusion was significantly lower in those with small for gestational age infants, indicating that pCASL-measured perfusion may be an effective imaging biomarker for placental insufficiency and provide the ability to test therapeutic interventions and monitor placental development.