Application of Microvascular-Flow Imaging to Characterize Placental Microvascularization in Preeclamptic and Healthy Pregnancies

Background: Preeclampsia (PE) is a common pregnancy complication and involves placental dysfunction and ischemia. Microvascular-Flow (MV-Flow) imaging was utilized to quantitatively assess placental microvascular architecture in PE. MV-Flow was also used to compare the microvascular architecture between PE and normal pregnancies, as well as between early- and late-onset PE cases. Methods: The study enrolled 87 consecutive singleton pregnancies that underwent MV-Flow imaging examination between June 2021 and December 2021. Among these, 50 were normotensive pregnancies and 37 were PE pregnancies. The PE group was further stratified into early-onset (<34 weeks gestational age [GA], n = 25) and late-onset (≥34 weeks GA, n = 12) subtypes. Among the 50 normal cases, 38 were <34 weeks, and 12 were ≥34 weeks. MV-Flow technology was used to measure the placental vascular index (VIMV). The VIMVs for the middle and peripheral placental segments were referred to as VIMV-m and VIMV-p, respectively. Placental VIMVs were compared between PE and normotensive pregnancies, as well as between early- and late-onset PE cases. Perinatal outcomes were evaluated in pregnancies complicated by PE. A p-value < 0.05 (two-sided) was considered to be statistically significant. Results: No significant difference between the VIMV-p and VIMV-m was observed in either the normotensive or PE group, and neither parameter correlated with GA. Both VIMV-p and VIMV-m were significantly lower in early-onset PE cases compared to normotensive pregnancies <34 weeks GA (p < 0.001). Similarly, late-onset PE cases also showed lower VIMV-p and VIMV-m compared to normotensive pregnancies ≥34 weeks GA (p < 0.001). No significant differences were observed between early- and late-onset PE cases in either VIMV-p (p = 0.170) or VIMV-m (p = 0.471). Among PE pregnancies, placental VIMV measurements revealed no significant differences between appropriate-for-GA (AGA) and small-for-GA (SGA) neonates (VIMV-p: 21.40 [17.70–27.30] vs. 21.50 ± 2.50, p = 0.949; VIMV-m: 21.30 [17.50–27.50] vs. 22.80 ± 6.40, p = 0.881). Conclusions: MV-Flow imaging enables quantitative assessment of microvascular architecture in PE placentas. Both early- and late-onset PE pregnancies showed significantly lower placental VIMV compared to normotensive pregnancies, supporting the clinical utility of MV-Flow for the evaluation of placental perfusion in PE. Furthermore, no significant difference in placental VIMV was observed between early- and late-onset PE, suggesting a similar impairment of placental perfusion in both subtypes.