Novel application of 4D sonography with B-flow imaging and spatio-temporal image correlation (STIC) in the assessment of the anatomy of pulmonary arteries in fetuses with pulmonary atresia and ventricular septal defect.

OBJECTIVES

To assess the reliability of two-dimensional gray-scale (2D) and color Doppler echocardiography in the study of the size and anatomy of the central pulmonary arteries and of the sources of pulmonary blood flow in a case series of fetuses with pulmonary atresia and ventricular septal defect (PA-VSD), and to evaluate whether the use of 4D ultrasound with B-flow imaging and spatio-temporal image correlation (STIC) can improve prenatal diagnostic accuracy.

METHODS

The study population comprised a group of seven PA-VSD fetuses that had been examined by 2D and color Doppler echocardiography exclusively, and a group of five additional cases identified initially by conventional echocardiography and examined further by 4D ultrasound, for all of which a thorough postnatal or autopsy study of the size and anatomy of the pulmonary arteries and blood supply was available.

RESULTS

2D and color Doppler echocardiography failed to assess the anatomy of the central pulmonary arteries and the source of the pulmonary blood supply in 33% and 25% of the 12 cases, respectively. 4D ultrasound with B-flow imaging and STIC assessed successfully the anatomy of the pulmonary arteries and the source of pulmonary blood supply in all five fetuses examined.

CONCLUSIONS

The prognosis of PA-VSD is influenced by the anatomy of the pulmonary arteries and the sources of the pulmonary blood supply, and by coexisting extracardiac and genetic anomalies. Our findings, although limited to a small sample size, suggest that 4D echocardiography with B-flow imaging and STIC, unlike 2D ultrasound, can provide thorough visualization of very small vessels and of the arterial blood supply to the lungs of fetuses with PA-VSD. 4D ultrasound may be used in the future to improve and help to detail the diagnosis of other fetal cardiac defects.