A summary measure of backscatter anisotropy in the non-pregnant cervix

The uterine cervix contains pseudo-aligned and crosslinked collagen. As the cervix softens during pregnancy in preparation for childbirth, the crosslinks degrade and the collagen becomes disordered, resulting in softening (“ripening”). Preterm birth is associated with preterm cervical change, and therefore early detection of this process could allow earlier intervention. Previous studies have demonstrated that acoustic backscatter with steered beams can demonstrate an excess loss in backscattered power (beyond that observed for spherical scatterers) that is indicative of the presence of aligned scattering structures. We sought to determine whether we could develop a metric for objectively analyzing collagen organization in human (nonpregnant) cervical specimens. Hysterectomy specimens were obtained from 36 subjects, 12 of whom were ripened. A summary metric, S, of eBSPL surface plots incorporates their symmetry and the total eBSPL. The two-sample Kolmogorov-Smirnov test for comparison of the S values for unripened versus ripened specimens confirmed a statistically significant difference between ripened and unripened specimens (p=0.019). However, more development and testing is needed before such a metric can be useful in detecting cervical ripening.