Imaging comparison of basic cardiac views between two- and three-dimensional ultrasound in normal fetuses in anterior spine positions

Objective: When the fetal spine is in anterior position, it shadows the fetal heart, resulting in the difficult visualization using two-dimensional (2D) ultrasound. The purpose of this study was to compare the basic cardiac views of normal fetuses between 2D and 3D ultrasound to demonstrate whether 3D ultrasound improved the visualization of these views in fetuses in anterior spine positions. In addition, inter- and intra-observation reliabilities of basic cardiac views using 3D ultrasound were evaluated for their clinical applicability. Methods: Using a multiplanar technique, integrated 3D ultrasound was used to display the four-chamber view, aortic outflow tract and pulmonary outflow tract in fetuses in anterior spine positions for 23 uncomplicated singleton pregnant women. The imaging visualizations of these views for the 23 fetuses in 3D ultrasound were compared with those in 2D ultrasound using the McNemar test. We also evaluated the inter- and intra-observation differences of each basic cardiac view in 3D ultrasound using the K statistic and McNemar test, respectively. Results: Only in the pulmonary outflow tract, 3D ultrasound had significantly better visualization than the 2D ultrasound in the fetuses in anterior spine positions (p < 0.05). There was good inter-observation reliability and no intra-observation differences for the technique were observed. Conclusions: Among the basic cardiac views in fetuses in anterior spine positions, 3D ultrasound improved the visualization of pulmonary outflow and provided reliable alternate technique for clinical use.