OP18.13: Spatiotemporal image correlation for evaluation of a fetal cardiac malformation: report on two complex cases

Abstract

Since 2002, spatiotemporal image correlation (STIC) has been used as a new approach to sonography of the fetal heart to give better analysis of the data. It aids in visualization in two-dimensional (2D) and three-dimensional (3D) scans with cine sequences. Volume acquisition is carried out by automatic volume sweep of an appropriate 2D apical four-chamber view, after which the system analyzes the data according to their spatial and temporal domain and processes a dynamic 3D image sequence represented in a multiplanar reformatted cross-sectional, surface- or volume-rendered display. The Doppler mode can also be activated and flow can be displayed in 3D. Postprocessing employs simple principles: a dot in the triplanar display is moved for a translation, then rotation on the x-, y- or z-axis is carried out to visualize structures of interest. Reproducibility has been proved for the study of left and right outflow but other anatomic cardiac elements are accessible after further training. We present a case of Ebstein's anomaly in which 4D STIC offered much of its potential. The dilated and atrialized right ventricle shows ideal echogenicity and flow. Further, the pathologic tricuspid septal valve allows structural and cinematic analysis by different axis surface rendering that is impossible by standard sonography. Ventricular volume, right outflow and sigmoid valves can be visualized for a quick prognosis. In a second case, a hypoplastic left ventricle was analyzed. The aortic and mitral valves are extremely difficult to describe in this pathology by conventional techniques. We show that STIC is useful for precisely depicting the degree of stenosis, atresia or hypoplasia. The left ventricular volume and contractility can be displayed in 3D. 4D STIC has multiple applications and lends itself to storage and review of volume data by experts at a remote site; it provides the ability to review all the images in a looped cine sequence. We believe that this technique can improve the accuracy of sonographic diagnosis and help prenatal counseling.