B-flow/spatiotemporal image correlation M-mode: a novel ultrasound method that detects a decrease in spiral artery luminal diameter in the first trimester in a primate model of impaired spiral artery remodeling

OBJECTIVE To determine if B-flow/spatio-temporal image correlation (STIC) M-mode ultrasonography detects a decrease in spiral artery luminal diameter and volume flow during the first trimester in a nonhuman primate model of impaired spiral artery remodeling (SAR). METHODS Baboons were treated with estradiol on days 25-59 of the first trimester of pregnancy (term = 184 days). Spiral artery luminal diameter and volume flow were quantified by B-flow/STIC M-mode ultrasonography on day 60 of gestation and results compared with the percentage of spiral arteries remodeled by extravillous trophoblasts as quantified ex vivo by immunohistochemical image analysis on placental basal plate tissue collected via cesarean section on day 60. RESULTS The percentage of spiral arteries greater than 50 μm in diameter remodeled by extravillous trophoblasts was 70% lower (P = 0.000001) in estradiol-treated baboons than in untreated animals. Spiral artery luminal diameter at systole and diastole, as quantified by B-flow/STIC M-mode in the first trimester of pregnancy, was 32% (P = 0.014) and 50% (P = 0.005) lower, respectively, and volume flow 85% lower (P = 0.014) in SAR suppressed baboons than in untreated animals. There was a significant (P < 0.05) correlation between the level of spiral artery luminal diameter as quantified by B-flow/STIC M-mode ultrasonography and level of SAR. CONCLUSION B-flow/STIC M-mode ultrasonography provides a novel real-time noninvasive method to detect a decrease in uterine spiral artery luminal diameter and volume flow during the cardiac cycle in the first trimester in a nonhuman primate model of defective SAR. This article is protected by copyright. All rights reserved.