Ebstein anomaly is a rare congenital heart disease that accounts for <1% of all congenital heart diseases. It is characterized by a congenital malformation of the tricuspid valve and the right ventricle (RV) [1]. Carpentier and Celermajer classifications, which are based on echocardiographic findings, have been used to predict the clinical outcomes in Ebstein anomaly [1] and to determine the surgical options according to its severity [2]. However, echocardiography cannot provide an accurate volumetric severity index (SI). Cardiac MRI has also been used to quantify ventricular volumes and function in Ebstein anomaly. However, cine MRI is limited by its ability to accurately segment the malformed tricuspid valve and RV endocardial borders because of its two-dimensional (2D) nature [3][4][5][6].Cardiac MRI is generally limited by its long examination time, which often requires conscious sedation or general anesthesia. In addition, the threshold-based segmentation results of threedimensional (3D) whole-heart MRI data are often influenced by inhomogeneous signal intensity and imaging artifacts [7]. In contrast, cardiac CT is increasingly used to evaluate congenital cc This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/bync/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Objective: The purpose of this study was to demonstrate the feasibility of using cardiac CT to perform volumetric severity assessment of the Ebstein anomaly.
Materials and Methods:Six children with Ebstein anomaly were included. We used cardiac CT to measure the delineated tricuspid valve, streak artifacts, and contrast enhancement heterogeneity. Cardiac CT data were used to quantify the volumes of all of the cardiac chambers, including the atrial and functional right ventricle (RV). In addition, the functional RV (fRV) fraction, fRV/left ventricle (LV) volume ratio, and total right/left-volume index were calculated. The volume-based CT severity index was compared using area-based echocardiographic and CT severity indices.Results: All of the patients had grade 3 or 4 extent of delineation of the malformed tricuspid valve and streak artifacts. In one case, the right atrium had image noise [126.7 Hounsfield units (HU)] that was >50 HU, while all others demonstrated image noise <50 HU. This image quality was appropriate to make all of the volumetric measurements. The RV volumes were enlarged in 83.3% (5/6) of the cases. The fRV fraction was 60.8-61.5%. The fRV/LV volume ratio and total right/left-volume index were 2.0±1.4 and 3.5±1.5, respectively. There was a smaller difference (0.2±0.1) between the area-based and volume-based CT severity indices than there was in other comparisons. These parameters also had a higher concordance rate (83.3%, 5/6) in the severity grades.
Conclusion:Volumetric severity assessment using cardiac CT is feasible in Ebstein anomal...