When you have two groups of images from different studies (different frames of reference), the patient may have been in a different position. Because of the change in position, even if the group of images shows the same area of the body, the images cannot be automatically synchronized.
To synchronize the images, you can do one of the following:
Link the groups manually
To link the groups manually:
1. Manually scroll to find matching images in the groups being linked.
2. Click Link 
.
The cursor changes to a chain icon (Link mode).
The groups are synchronized according to the images displayed when you clicked Link.
NOTE: If after making a link, you realize that the synchronized images do not match, you can select another image to link. Hold down the Shift key and scroll until the correct image appears. The groups resynchronize when you release the Shift key.
3. To stop Link mode, click another tool.