Evaluation of RT3DE data

For each subject the RT3DE volume data set of the best image quality was imported to the Ventripoint Medical System (VMS) software (version 1.2.6905.4788, Ventripoint Diagnostics Ltd., Bellevue, WA) and the tool “Right Ventricle” for healthy right ventricles was used for the further computation.

End-systolic and end-diastolic frames were identified in the four-chamber view as the smallest and largest RV-cavity respectively in representative 2DE reformatted planes. The same end-systolic to end-diastolic interval was automatically applied to all other views in the same data set. A set of anatomic landmarks such as the pulmonary valve annulus, the tricuspid valve annulus, apex, interventricular septum, and RV endocardium were then plotted in the end-systolic and end-diastolic data sets. Endocardial landmarks were placed at the bases of trabeculae therefore including them into the RV cavity volumes. A minimum of 11 points were required to create a 3D model. The plotted anatomic landmarks and their 3D special coordinates were then transmitted to a remote server via a secure internet connection and a RV model was created using a knowledge-based reconstruction algorithm referring the plotted points against a catalogue of templates for hearts with normal shapes on the knowledge data base in VMS (Figure 1) (15).

3D right ventricular models based on the Knowledge-Based Reconstruction after setting of anatomical landmarks. (A) Contour model of the RV border (yellow line) superimposed into a 4-chamber view reconstructed from the RT3D full volume, crosses depict the previous placement of landmarks. (B) 3D-model including mesh structure, points, outlines, and borders in a 4-chamber view. (C) Same presentation as b in a short axis view. (D) Combined view of outlines and borders of the 3D-model in end systole (blue) and end diastole (purple mesh). Colour coding: red: RV endocardium, blue: interventricular septum, pink: pulmonic annulus, purple: tricuspid annulus, yellow: apex.

The resulting 3D models could be superimposed on the original scan plains and the intersections inspected. In rare cases, where alignment between the surface of the 3D model and either the plotted points or the echocardiographic borders were not satisfactory, points were repositioned, removed, or added as required and the algorithm rerun. The VMS software uses the 3D models to calculate the respective end-systolic and end-diastolic volumes as well as stroke volume and ejection fraction. The use of KBR for the calculation of RV volumes in 3DRT datasets method has already been systematically evaluated by our group (15).