**8.2. Three-dimensional echocardiography**

Three-dimensional image resolution is dependent on the quality of the 2D picture; therefore, optimizing the image prior to changing to 3D mode is essential. Select the imaging plane or acoustic window with the highest resolution. Imaging in the axial plane provides superior resolution (0.5–1 mm) followed by lateral (1.5–2 mm) and finally elevational resolution (2.5–3 mm) [123]. When performing 3D TTE, select the window that transects the structure of interest through the axial and lateral plane such as the parasternal long axis for the mitral valve.

To allow for optimal postprocessing, it is recommended the gain, compensation, and compression be in the midrange, with the TGC adjusted to display a uniform, slightly brighter image [124]. As spatial resolution increases, temporal resolution is reduced and vice versa. This is due to the limited number of scan lines that can be performed in a fixed period of time. To improve image resolution, narrow the sector width and optimize frequency, compression, and focus [124, 125].

Multibeat 3D volume rendered image acquisition is limited by 'stitching' artifact from respiration and/or arrhythmia [124]. This can be addressed with breath holding and ensuring image acquisition during regular R-R intervals on the ECG.

Cropping of the 3D dataset can be performed en cart prior to image storage or alternatively, offline on a workstation using proprietary software. The 3D data can then be displayed as volume rendered format and surface rendered format or 2D tomographic slices [123].

Finally, the 3D rendered image is rotated and orientated according to convention. The mitral valve from the left atrial perspective (surgeon's view) with the aorta superiorly (12 o'clock), the aortic valve with the right coronary cusp inferiorly (6 o'clock), the tricuspid valve with the interventricular septum inferiorly (6 o'clock), and the pulmonary valve with the anterior cusp superiorly (12 o'clock). The display formats remain the same regardless of whether the valve is viewed from above or below [124].
