Introduction
Thorough assessment of the cardiovascular anatomy with two-dimensional ultrasonography requires the operator to scan these vascular structures in multiple scanning planes to obtain a mental reconstruction of their spatial relationships1. The introduction of four-dimensional echocardiography using STIC facilitated examination of the fetal heart by navigating through the volume data set in an unlimited number of cutting planes. Since then, STIC technology has been widely used for cardiac evaluation in a diagnostic setting. A growing body of scientific work has shown that application of STIC technology potentially aids in improving congenital heart defects (CHD) detection2,3. However, more than a decade ago, studies on the effectiveness of STIC echocardiography failed to confirm its superior clinical value for CHD detection compared to conventional 2D ultrasound both in experienced and less experienced hands4,5. As fetal echocardiography using STIC requires extra time and effort and exhibits a strong operator dependency, its usefulness, particularly in a screening setting, has been doubted.
With the advancement of an intelligent navigation approach applied on STIC volumes, 4D echocardiography has been considerably simplified. With marking of the proposed anatomical structures, all nine diagnostic planes for comprehensive cardiac evaluation are semiautomatically reconstructed. One of the advantages of intelligent over manual navigation in volumetric sonography is the short time required for acquiring the volume, marking and displaying all the cardiac view, along with the added benefit of ‘guided’ orientation and identification of anatomical structures6.
In part II of this paper, we focused on the additional diagnostic value of fetal intelligent navigation echocardiography (FINE) in the evaluation of the altered anatomy in left-sided cardiac lesions simultaneously displayed in axial and longitudinally planes. We will further discuss recent advances in 4D echocardiography and give a concise overview of future perspectives on this technique for evaluating fetal anatomy.