![]() Kaufmann, “ Aspects of human fetoplacental vasculogenesis and angiogenesis. Charnock-Jones, “ Aspects of human fetoplacental vasculogenesis and angiogenesis. Kaufmann et al., “ Structural analysis of placental terminal villi from growth-restricted pregnancies with abnormal umbilical artery Doppler waveforms,” Placenta 17, 37– 48 (1996). Sinkus, “ A unifying fractional wave equation for compressional and shear waves,” J. Oncul et al., “ Shear wave elastography of placenta: In vivo quantitation of placental elasticity in preeclampsia,” Diagn. ![]() Shimokawa, “ A new method for measurement of placental elasticity: Acoustic radiation force impulse imaging,” Placenta 34, 1009– 1013 (2013). Dahlke et al., “ Screening for intrauterine growth restriction in uncomplicated pregnancies: Time for action,” Am. Pratt, “ Routine ultrasound in late pregnancy (after 24 weeks' gestation),” Cochrane Database Syst. Fleming, “ The relation between fetal abdominal circumference and birthweight: Findings in 3512 pregnancies,” Br. Kramer, “ Decreased term and postterm birthweight in the United States: Impact of labor induction,” Am. Van Look, “ WHO analysis of causes of maternal death: A systematic review,” Lancet 367, 1066– 1074 (2006). An ex vivo feasibility of the method on 20 normal placentas is presented in this work. This model provides a parameter n which could be sensitive to a shape factor, for example, the variations in the number of villi ramifications in the case of placental insufficiency. To be particularly sensitive to the structure of this organ, a frequency analysis of the complex shear modulus has been realized by applying a fractional rheological model. In this context, we proposed to develop a 2-D transient elastography system, dedicated to the placenta and adapted for in vivo measurements, based on the coupling of a shear wave generated by an external vibration and ultrasound images acquired at an ultrafast rate. These changes affect the entire placenta and might lead to variations in elasticity compared to normal placentas. Significant changes in placental microarchitecture have already been described in these situations, including, for example, increases or decreases in the number of villi ramifications and the presence of fibrin deposits in terms of villi. Preeclampsia and intrauterine growth restriction are related to placental insufficiency and constitute a major public health challenge.
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