Image Viewer > Advanced Viewing > Synchronized Stacking

It is often useful to synchronize the viewing of different stacks of images that are in the same plane. For example, you may have two sets of axial CT images that were acquired with different parameters, but you want to view them together. That is, as you stack through one, you want the other to be synchronized according to slice location.

Synchronization within a study

If a study contains more than one series in the same plane whose images cover the same region of the body, synchronizing these series is straightforward:

1.	Bring up the different series you wish to synchronize. The series need to be in the same plane.

2.	Click on the Synchronize Stacking button on the toolbar.

In the figure below, the two visible series have been synchronized. Note the slice location of both images.

Screenshot

Sometimes, it is also useful to have a synchronized view of the same series under say, two different window/level settings. This can be done by using the context menu and dropping the same series into two different image boxes, then synchronizing them.

Synchronization between studies

A common synchronization scenario is one in which two studies need to be compared. However, it is often the case that there is an offset between them because the scans were done on different dates, and perhaps on different equipment. So, simply synchronizing by slice location is often not good enough, as that offset must be accounted for.

To synchronize two (or more) different studies:

1.	Bring up the series from the different studies you wish to synchronize. The series need to be in the same plane.

2.	Click the Synchronize Stacking button on the toolbar. Like the single study case, this will synchronize the series within each study. However, when two or more studies are loaded, it will also perform an automated naive synchronization between studies based on slice location.

3.	If the automated synchronization between studies is poor (i.e., there is an unacceptable offset between them), click on the Unlink Studies button. This will turn off the synchronization between studies.

4.	Manually synchronize the studies by stacking one of them so it lines up with the other.

5.	Click the Link Studies button (i.e. the same button as the Unlink Studies, except the icon has changed) to re-link the studies.

6.	When you stack through either study, you will notice that the manual offset you introduced is preserved, and the studies should be properly synchronized.