15: Novel, sensor-based quantitative cervical elastography: objective quantification of cervical softness

Abstract

Cervical ripening is a necessary physiologic phenomenon that precedes all labor, both term and preterm. Tissue elastography works by applying pressure to tissue and measuring tissue displacement. It is quantified by Young’s modulus, a ratio of pressure to displacement. The harder the tissue, the less displacement and the higher the Young’s modulus. It is a promising technique for measuring cervical tissue stiffness to predict preterm birth, but to-date has been semi-quantitative because the exact force applied to the cervix is difficult quantify. We aimed to develop a novel, fully-quantitative cervical elastography system to objectively quantify cervical tissue stiffness. A transvaginal ultrasound probe was modified with a pressure sensor at the tip to obtain real time synchronized pressure and tissue displacement measurements. Pressure and displacement were quantified to calculate the Young’s modulus (Figure1). This system was applied in a pilot prospective cohort study of women receiving prenatal care at a tertiary care center and enrolled in a longitudinal observational study with the larger aim of developing novel predictive methods for PTB. Generalized linear models were used to test changes in Young’s modulus (cervical stiffness) over advancing gestational age to determine if the tissue Young’s modulus decreases with advancing gestational age as expected with softening. A total 26 ultrasound elastography images from 12 patients were analyzed (9 term births and 3 preterm births). The Young’s modulus of cervical tissue tended to decrease with advancing gestational age (-0.65 Young’s modulus units per day) (Figure 2). We report a novel, sensor-based, fully quantitative cervical tissue elastography system using a modified transvaginal ultrasound probe for synchronized tissue deformation and pressure measurements. As expected, Young’s modulus tended to decrease over pregnancy as the cervix softens. This objective quantification of cervical tissue stiffness may be a promising tool for predicting preterm birth.View Large Image Figure ViewerDownload Hi-res image Download (PPT)