Fetal cardiac interventricular septum: volume assessment by 3D/4D ultrasound using spatio-temporal image correlation (STIC) and virtual organ computer-aided analysis (VOCAL)

Abstract

Objective: To determine reference values for fetal interventricular septum (IVS) volume by 3D/4D ultrasound using spatio-temporal image correlation (STIC) and virtual organ computer-aided analysis (VOCAL).

Methods: A prospective cross-sectional study was conducted on 200 consecutive normal low-risk pregnant women at a gestational age ranging from 18w0d to 33w6d. The volume data sets of the fetal heart were acquired by applying STIC to a four-chamber plane. IVS volume was calculated offline using VOCAL with rotation of 30° (six planes). To assess the correlation of fetal IVS volume as a function of gestational age (GA), Pearson’s correlation coefficient (r) and polynomial regression models with adjustments through the coefficient of determination (R²) were calculated. The intra-class coefficient (ICC) was used to evaluate intra- and inter-observer reproducibility.

Results: A good correlation between GA and fetal IVS volume (r = 0.827) was observed. The mean fetal IVS volume ranged from 0.13 ± 0.03 cm³ (0.08–0.18 cm³) at 18wd0 of gestation to 1.33 ± 0.37 cm³ (0.41–1.98 cm³) at 33w6d. The best correlation between fetal IVS volume and GA was exponential: fetal IVS volume = 0.11e^0.139×GA (R²= 0.785). A good intra- and inter-observer reliability were observed, with ICC = 0.999 and 0.991, respectively.

Conclusions: Reference values for fetal IVS volume using STIC and VOCAL by 3D/4D ultrasound between 18w0d and 33w6d of gestation were determined and showed to be reliable and concordant.

 :

• Echocardiography
• fetus
• interventricular septum
• reference value
• three-dimensional ultrasound

Declaration of interest

The authors would like to thank the Brazilian National Council for Scientific and Technological Development (CNPq) for the scientific initiation scholarship for the medicine undergraduate Priscila Henriques da Silvas.