“Real-time” means that the 3D image is being visualized live (simultaneously with the cardiac anatomy and function in that particular moment, as in 2D). “Stitched acquisition” is a 3D image obtained from several consecutive cardiac cycles and its complete visualization is delayed until the last cycle, therefore the final 3D image is “almost” but not actually real-time (typical only for 3D acquisition). The difference between the two modalities of acquisition becomes most relevant during monitoring procedures, when real-time scanning is required.
Beutel is the German term standing for “bag” or “sac” and it is commonly used when referring to the left ventricular cavity surface reconstruction obtained by 3D echo software.
The stitching artifact means a discontinuation in the 3D volume rendering reconstruction at the interface between adjacent subvolumes.
Usually, scanning patients with suboptimal quality of 2D images will result in even worse 3D data sets. However, by 3D echo the visualization of a determined cardiac structure is not restricted anymore to just a single acoustic window, as it may happen with 2D (e.g. en face views of the aortic or mitral valve from parasternal windows). A 3D data set of a specific structure can be acquired from any window with good echogenicity (e.g. from apical window, when the parasternal one is not adequate) and then it can be cropped to show the structure of interest. In addition, if the goal is to assess chamber volumes and function and the apical acoustic window is inadequate, contrast agents can be used when, as with conventional 2D echo.
Usually it is. Good quality data sets can be cropped and navigated until the structure of interest can be shown from the desired perspective. However, it should be taken into account that the larger is the 3D data set, the lower will be the temporal and spatial resolution. Therefore, dedicated smaller volumes centered on each structure of interest (i.e. mitral valve, tricuspid valve etc) usually provide better results.
Usually chamber volumes measured with 3DE are larger than those calculated with conventional 2D echo and closer to those measured with cardiac magnetic resonance. Their interpretation is somewhat challenging at present, since we do not have yet robust reference values obtained from the general population for all cardiac chambers, and the cut-off values derived from conventional 2D echo are probably not appropriate for 3D. However, 3D volumes can be used in the longitudinal follow-up to document chamber remodelling.
3D echo does not allow a tissue characterization of cardiac masses. The different colorization is only related to the location (depth) of the mass with respect to the observer’s point of view. However, 3DE can provide more precise informations on the size, shape and mobility of the mass, and usually allows a clear identification of the site of attachment and of the spatial relationship with adjacent structures.
By reducing the volume size and/or increasing the number of subvolumes to be stitched together in a multi-beat acquisition (recommended), or by reducing the spatial resolution.
You may try to acquire a data set containing the whole left ventricle from other approaches (i.e. subcostal or parasternal) or you can use the apical approach with contrast agent injection.
Definitely. 3DE allows a complete visualization of the entire myocardium and, if the quality of the data set is adequate, any wall motion abnormality can be theoretically identified during postprocessing (even those located in between conventional 2D views), by careful slicing with re-orientation of the cut planes in a multi-slice display. In this way, images can be corrected for off-axis views and chamber foreshortening, allowing to reliably appreciate the extension of the wall motion abnormality in both longitudinal and circumferential directions.
Of course, it depends on the skill of the operator and patient’s tolerance during the examination. However, it is usually feasible only with local anesthesia in 90-95% of patients, as with conventional 2D TOE. Actually, the conscious patient may cooperate for breathholding in order to obtain also large multi-beat 3D data sets, that can be cropped during postprocessing after the end of the examination, if further informations are needed.
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