imginteg can help you calculate an AUC (integral over time) image from PET image in ECAT 6.3, 7.x or Analyze 7.5 format. In case of static image, the matrix values are simply multiplied by the frame duration.
The pixel values of resulting integral image will be in units of radioactivity concentration times sec.
The command line arguments are :
1. PET image
2. AUC calculation start time (sec)
3. AUC calculation duration (sec)
4. AUC image file

Options:
-avg
Average during specified range is calculated instead of AUC
-min
AUC times are given in minutes instead of seconds
-h or --help
Print this message and exit
--version or --build
Print software build information and exit
--silent
Program works silently, printing only error and warning messages
--verbose
Program prints more information about what it is doing.

Program will automatically set the integration start time or duration based on the time range in the image, if either is set to zero.

The license of this software is Freeware, you can free download and free use this calculator software.