Transforming Images into Standard Short Axis Orientation

The next step is to rotate the images into the standard short axis orientation, see Standard Reorientation of the Heart. An automatic procedure is available, but when it fails a manual interaction is required.

Manual Reslicing

As soon as the averaging process has completed, the display shows the MYOCARDIUM images and is switched into the reslicing mode.

The button provides a quick way to bring the images into an approximate short-axis orientation. The fine-adjustment can then be done using the handles which are shown in each of the orthogonal slices:

• The large open rectangle in the image center serves for shifting the images along the axes: click the left mouse button into the rectangle and drag the image into the desired direction.
• The small closed rectangle connected to the image center allows to rotate the images: click the left mouse button onto the rectangle and drag around the center.

As an alternative to the mouse-operated reslicing numerical values can be entered on the Move and Rotate tabs. If anything goes wrong the transformation can be reset with the button.

Once the right orientation has been found it is recommended to exit the reslicing mode in order to avoid unintended manipulations of the orientation. To this end, select any other tab such as the image presentation tab .

Automatic Reslicing

The PCARD tool offers an automatic procedure for the short axis reorientation. As soon as the button indicated below is activated the procedure is started.

The images are reoriented, and the resulting parameters shown in the reslicing tab.

The box next to the reorientation button is for enabling the automatic mode. If it is checked, the reorientation process is started as soon as anatomical images are generated or loaded.

The arrow below the box can be used to copy the short axis transformation from rest to stress, and vice versa. If the transformation is copied, the target images are immediately resliced. Note that due to patient motion between the studies the copied transformation may not be fully adequate. In this case please fine-tune manually using the handles as described in Manual Reslicing above.

If the automatic reorientation returns an inadequate result, it can be supported by manually defining the left ventricle using a marker. Please proceed as follows:

• Reset the orientation using the button indicated above.
• Click into the images until the orthogonal planes intersect in the LV center.
• Select the button, and click into the LV. A marker appears as illustrated below.
• Activate the automatic reorientation button again.

Correct Short Axis Orientation after Reslicing

Please verify, that after the automatic and/or manual reorientation the images are oriented as illustrated below:

For the automatic contouring and the subsequent segmentation it is very important that the septum appears to the left in the SA slice. This can be verified by checking the right ventricle in the BLOOD images, which are also shown with the same transformation parameters. For the automatic contouring it is also helpful if the heart is centered in the center of the image volume.

Saving Transformations

It is recommended to save the transformations before proceeding to the next step using the button in the lower part of the reslicing pane. By loading this transformation at a later time, the processing can precisely be repeated.