PET/CT Comparison is a display option that automatically loads two studies. Whenever you select a current study and load it to the PET/CT application, PET/CT Comparison loads the prior PET/CT study automatically. The two studies show as current and prior in this comparison display option and are automatically registered.
You can load studies to PET/CT Comparison either from the Archive Explorer or by using a layout option from the Layout tab once the PET/CT application is launched. When you load studies to PET/CT Comparison from the Archive Explorer, the default layout is a 2 x 4 layout (one current and one prior study). To use other layouts or display more than one prior, load a study to PET/CT and select one of the layout options from the Layout tab.
Selecting a comparison option of more than one prior automatically loads all the relevant priors and displays them in the layout.