FDTD simulations for ultrasound propagation in a 2-D cervical tissue model

The cervix is a biochemically active tissue that changes its biomechanical properties in a remodeling process during pregnancy to be prepared for parturition. This maturation process is associated with changes of the mechanical properties of the cervical stroma. Preterm delivery is connected with undesired cervical changes bound to cervical ripening. Non-destructive evaluation using ultrasonic signals is a wellestablished method to obtain physically relevant mechanical parameters, and thus ultrasonic may be an useful tool to diagnostic preterm birth. A two-dimensional finite difference model for mechanical waves in the collagenous tissues has been developed, and used to understand how propagation of ultrasound is affected by the hierarchical structure of cervical tissue during pregnancy. The model simulates the wave propagation through two different soft tissues: a micrograph from human cervical tissue, and an artificially created profile with random generated fibers. Results show the ability of the proposed model to describe the mechanical behavior of the cervical tissue as a fiber-reinforced material, and that the ultrasonic wave propagation phenomena can be exploited to reconstruct the mechanical properties of soft tissues.