Persistent infection.

Hi,
Just a query really. If I have a clean disk image on an external hard drive and use this to restore my whole PC , ie all disks and partitions, is it possible for a virus that was on the PC to be still present after the restoration ?
As the disk is reformatted as part of the restoration procedure I always thought any virii etc would be totally eradicated but I have been told this is not necessarily the case and problems could still persist, as putting a disk image on does not remove absolutely ALL software , such as software required for powering up etc.
When I put on a disk image I use a bootable CD to take me in to the recovery mode. I use Macrium Reflect as the disk imager and restorer.
Any thoughts would be welcome.
Regards Alex

 

Thanks TimW,
It's appreciated that you took the time to reply.
Alex