Mid-esophageal LV views without foreshortening (Figure 2 & 3)
After inverting the z-axis and moving the MPR crosshairs into the esophageal lumen, we simulate “turn to the left” by rotating the sagittal MPR line counterclockwise on the axial MPR plane to make the sagittal plane cross the LV apex. Then we can easily use the sagittal plane to discern that at different level of esophagus, different degrees of retroflex are needed to avoid LV foreshortening. With a LV image without foreshortening, we can rotate the reference plane on the coronal MPR plane to obtain LV 4-chamber, 2-chamber, bi-commissural and long-axis images.
Orthogonal interrogation of ultrasound beams obtains the highest reflection to deserve the most precise resolution. As a result, by acquiring the mid-esophageal LV views with the ideal orientation, the imagers can reconstruct the high-resolution 3D mitral valve en face views. However, if the LV axis crossing from the center of mitral valve to LV apex is not contained in the plane of ultrasound scanning beams, there will be configural differences between TEE and CT imaging. On CT TEE simulation, we can easily discern such configural differences by investigating whether the sagittal MPR line on the axial plane crosses the center of mitral valve or not (Figure 3C). Sometimes a little “flex to the right” can partially ameliorate the configural differences. This effect can also be easily realized by CT simulation as a parallel movement of the sagittal line of sector from lateral annulus toward the center of mitral valve on the axial plane. It is important for the operators to understand such configural differences or they will be confused by intraoperative TEE imaging, because the more the configural differences appear, the higher the possibility that the devices make out-of-plane motion on TEE imaging.