Sure you can. Dump the image to a working copy, mount it, and you can do anything you want to to it. You'll still have an archival copy of the image to refer back to as well. This is standard procedure when doing computer forensics. It is not rocket science.
I would say it depends on whether the image is a hardware or software image. If software, the registry - the list of segments occupied by actively referenced file pieces - would only reflect the content of the registry, as opposed to the hardware itself, which will have all of the software-recognized files, plus segments of or complete files which have been deleted from the registry.
Hardware imaging software replicates every memory location on the device. Software imaging only replicates those files recognizable from the registry.
The problem lies not in the manipulation of the image, but rather in the manner in which the image is produced.