Reference values for the volumes of foetal heart atrial wall by three-dimensional ultrasound using STIC and VOCAL methods between 20w0d and 33w6d weeks of gestation

Objective: To establish reference values for the volumes of foetal heart atrial wall by three-dimensional (3D) ultrasound using spatio-temporal image correlation (STIC) and virtual organ computer-aided analysis (VOCAL) methods.

Methods: We performed a retrospective cross-sectional study with 170 normal singleton pregnancies between 20 weeks?+?0 days (20w0d) and 33 weeks?+?6 days (33w6d) of gestation. Foetal heart atrial wall volume was obtained by VOCAL method with 30-degree rotation (six planes) subtracting the internal volume from the atrium volume. Polynomial regression with adjustments by determination coefficient (R²) was performed. To calculate the interobserver reproducibility, concordance correlation coefficient (CCC) was applied.

Results: The mean?±?standard deviation (SD) for the left atrium wall volume (cm³) ranged from 0.54?±?0.21 at 20w0d–20w6d to 2.17?±?0.30 at 33w0d–33w6d. The mean?±?SD for the right atrium wall volume (cm³) ranged from 0.45?±?0.16 at 20w0d–20w6d to 2.17?±?0.62 at 33w0d–33w6d. We observed a satisfactory interobserver reproducibility with CCC?=?0.69 and 0.58 for the left and right volumes of foetal heart atrial wall, respectively. The best-fit models were first-degree: volume for the left atrium wall?=??2.194?+?0.139*GA (R^2?=^?0.41) and volume for the right atrium wall?=??2.757?+?0.155*GA (R^2?=^?0.37).

Conclusion: Reference values for the volumes of foetal heart atrial wall by 3D ultrasound using STIC and VOCAL methods between 20w0d and 33w6d weeks of gestation were established.