I just had a combined PET/CT scan (one year post-radiation) and they are certainly two different scans, but done simultaneously -- They inject you with radioactive glucose and then have you lay in a recliner in dim light for 30-45 minutes to allow the glucose to move around and accumulate in the places where it is processed or absorbed or whatever.

I requested a copy of the disk and they burnt it right after the scan, so likely I was home looking at it on my laptop before the radiologist found his copy in his inbox. I won't get the interpreted results until my visit to my ENT's office next week.

I scared the bejeepers out of myself looking at the disk, because there are one heck of a lot of 'hot spots' in my body (I requested a full body scan, which turns out to be from eyebrows to mid-thigh) -- My brain looks like the impact point for a MIRV of nukes, so either that's normal or I am among the Walking Dead.

Thought at first that my bladder (all lit up from processed glucose I presume) was my prostate (glance at an anatomy book cleared that up), but now to my untrained eye, my prostate looks good (been having some problems with that across the last couple of years, so that was an open question).

The two scans (267 images each) are viewable separately or 'fused' where they are keyed to each other, plus some other simultaneous views of my body, so scrolling down thru my body, a la Fantastic Voyage, I can see a hot zone in PET and look at the corresponding slice in CT, all lined up with crosshairs -- Cool stuf!