Prenatal quantification of human foetal lung and liver elasticities between 24 and 39 weeks of gestation using 2D shear wave elastography

Abstract

Objectives: To quantify and model normal foetal lung and liver elasticities between 24 and 39 weeks of gestation (WG) using two-dimensional shear wave elastography (2D-SWE). To assess the impact of the distance between the probe and the target organ on the estimation of elasticity values.

Methods: Measurements of normal foetal lungs and liver elasticity were prospectively repeated monthly between 24 and 39 WG in 72 foetuses using 2D-SWE. Elasticity was quantified in the proximal lung and in the region inside the hepatic portal sinus. The distance between the probe and the target organ was recorded. Trajectories representing foetal lung and liver maturation from at least 3 measurements over time were modelled.

Results: The average elasticity for the lung and liver was significantly different from 24 WG to 36 WG (p < 0.01). Liver elasticity increased during gestation (3.86 kPa at 24 WG versus 4.45 kPa at 39 WG). From 24 WG to 32 WG, lung elasticity gradually increased (4.12kPa at 24 WG, 4.91kPa at 28 WG, 5.03kPa at 32 WG, p < 0.002). After 32 WG, lung elasticity decreased to 4.54kPa at 36 WG and 3.94kPa at 39 WG. The dispersion of the average elasticity values was greater for the lung than for the liver (p < 0.0001). Variation in the elasticity values was less important for the liver than for the lung. The values were considered valid and repeatable except for a probe-lung distance above 8cm.

Conclusion: Foetal lung and liver elasticities evolve differently through gestation. This could reflect the tissue maturation of both organs during gestation.

Trial registration: clinicaltrials.gov identifier: NCT03834805 KEY POINTS: • Prenatal quantification of foetal lung elasticity using 2D shear wave elastography could be a new prenatal parameter for exploring foetal lung maturity. • Liver elasticity increased progressively from 24 weeks of gestation (WG) to 39 WG, while lung elasticity increased first between 24 and 32 WG and then decreased after 32 WG. • The values of elasticity are considered valid and repeatable except for a probe-lung distance above 8cm.

Keywords: Dispersion; Elasticity; Foetal liver; Foetal lung; Shear wave elastography.

Conflict of interest statement

The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article.

© 2022. The Author(s).

Figures

Fig. 1

Elasticity measurement of the proximal foetal lung with 2D-SWE in the region behind the plane passing through the atria after obtaining a B-mode image of a four-chamber view of the foetal heart. The colour box represents the elastogram (blue), and the yellow circle represents the region of interest (1 cm) where the elasticity measurement is acquired. The RMI (Reliability Measurement Index) value (0.5) is expressed below the obtained mean elasticity measurement of 2.7 kPa

Fig. 2

Elasticity measurement of the foetal liver in the region inside the hepatic portal sinus (segment V) with 2D-SWE after obtaining a B-mode image of abdominal circumference

Fig. 3

Average, maximum and minimum elasticity values for foetal lung and liver according to gestational age

Fig. 4

Dispersion of the average elasticity values for foetal lung and liver according to gestational age