Tissue elastography imaging of the uterine cervix during pregnancy.

Abstract

Tissue elastography is a recently developed tissue characterization method for estimating tissue stiffness. We investigated the feasibility of using US tissue elastography by evaluating uterine cervical maturation during pregnancy. The principle underlying elastography is that tissue compression produces strain (displacement) within the tissue, and that less strain occurs in hard tissue than in soft tissue. Tissue elastography thus enables the estimation of tissue stiffness by measuring compression-induced tissue strain. Malignant tumors are generally known to be harder than benign tumors in the breast, thyroid, and prostate. Various studies on these organs have demonstrated the usefulness of tissue elastography for differentiating malignant from benign masses in the clinical setting. Based on these results, we have begun to investigate the possibility of using tissue elastography to identify the population at high risk of preterm labor. We used a Hitachi EUB-8500 (Tokyo, Japan) ultrasound system equipped with a 7.5-MHz transvaginal sector probe to carry out transvaginal US examinations. After selecting the transvaginal sagittal image of the uterine cervix as the region of interest (ROI) in B-mode, we began real-time elastography of the ROI using only slight pressure, and displayed both the Bmode and elasticity images side by side on the same monitor screen (Fig. 1).