Quantitative assessment of cervical softening during pregnancy with shear wave elasticity imaging: an in vivo longitudinal study

Abstract

We report here the results of a longitudinal study of cervix stiffness during pregnancy. Thirty women, ages ranging from 19 to 37 years, were scanned with ultrasound at five time points beginning at their normal first-trimester screening (8–13 weeks) through term pregnancy (nominally 40 week) using a clinical ultrasound imaging system modified with a special ultrasound transducer and system software. The system estimated the shear wave speed (its square proportional to the shear modulus under idealized conditions) in the cervix. We found a constant fractional reduction (about 4% per week) in shear wave speed with increasing gestational age. We also demonstrated a spatial gradient in shear wave speed along the length of the cervix (softest at the distal end). Results were consistent with our previous ex vivo and in vivo work in women. Shear wave elasticity imaging may be a potentially useful clinical tool for objective assessment of cervical softening in pregnancy.

Longitudinal ultrasonic dimensions and parametric solid models of the gravid uterus and cervix

“…The age, race, ethnicity, pregnancy history, estimated gestational age (EGA) at each visit, EGA at delivery, and delivery outcomes were recorded for each patient. Details about this cohort, along with study size rationale, are published in Carlson et al [ 8 ]. The estimated date of delivery (EDD) was confirmed by ultrasound crown-rump length at the first study visit.…”

“…Care was taken to exclude from the CL the isthmus (IS), where the cervical mucosa ends [ 12 ]. During the TV exam, quantitative ultrasound data were also acquired from the cervix to measure tissue softness, as published in Carlson et al [ 8 ], for future integration into our models of information about tissue microstructure.…”

Why Are Viscosity and Nonlinearity Bound to Make an Impact in Clinical Elastographic Diagnosis?

“…Feltovich et al [233] proposed the elasticity as an interesting biomarker for physicians, since the elastic modulus varies more than 80 kPa while SWS varies from approximately 1.2 to 5.5 m/s over the cervix. Carlson et al [246] found in a longitudinal study that stiffness decreased over the course of pregnancy, and the same group explored the feasibility of SWS in capture the cervical softness in pre and post ripening in women experiencing induction for labor [241]. Peralta et al [247] used the commercial SSI to quantify the cervical stiffness at four ROIs, which evidenced that microstructural changes generate a measurable shear stiffness reduction that gradually undergoes throughout gestation.…”

Longitudinal ultrasonic dimensions and parametric solid models of the gravid uterus and cervix

“…The age, race, ethnicity, pregnancy history, estimated gestational age (EGA) at each visit, EGA at delivery, and delivery outcomes were recorded for each patient. Details about this cohort are published in Carlson et al [8]. The estimated date of delivery (EDD) was confirmed by ultrasound crown-rump length at the first study visit.…”