Shear wave velocity dispersion analysis in placenta using 2-D transient elastography

Abstract

Preeclampsia and intrauterine growth restriction are related to placental insufficiency and constitute a major public health challenge. 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. These changes affect the entire placenta and might lead to variations in elasticity compared to normal placentas. 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. 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. 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. An ex vivo feasibility of the method on 20 normal placentas is presented in this work.