Which is more accurate?

I was wondering if anyone knows which is more reliable...CT or PET? My wife had a CT which raised some questions...a shadow in her lung and 2 new tiny spots in her liver, in addition to a spot that had shown on a CT three months earlier which the doc felt might be scar tissue. To confirm any activity or not, she had a PET which came back completely clear! I wonder if it's scar tissue (which I understand why it wouldn't show on the PET) or could the CT be showing activity that's too small for the PET to pick up? I'm skeptical of it all being scar tissue because of the 2 new tiny spots in the liver.

I'm also wondering if she would be considered NED in case we decide to try and enter a vaccine trial.

Any insight is welcome.

Thanks, Eric

I have read that a PET scan when used after a CAT scan is extremely accurate! Congratulations!

[StephN]

Hi -
Annemarie's post is EXACTLY how I was pronounced NED after my liver mets. I went into this a little more in a post to Esther about her markers.

[Lolly]

...And the reverse is true, I had a CT which didn't pick up the areas that were subsequently identified as active disease by PET. So the PET is more accurate, however the standard is to use a CT first.
I'm keeping my fingers crossed for you that your wife's NED, and you can start thinking about a vaccine trial!

Love, Lolly

A CT will give you structural information and a PET will give you metabolic information. A CT will generally not pick up anything less than about a centimeter ( about 1/2 an inch ). I don't recall the exact numbers for the PET but it is somewhere in the 90+% range for picking up lesions.

There is a machine out now that does both CT and PET and fuses the images to tell the doctor if something lighting up on PET and something seen on CT correspond to each other. Right now I think this is the most accurate scanning available.

I know that UCLA, founders of PET scanning, is experimenting with different radioactive tracers trying to boost the sensitivity of detecting breast cancer.

When I was found to have liver mets, CT picked up 3 lesions but when I had surgery 8 lesions were found, so CT was less than 50% accurate for me.

So in a nutshell, I think it's great news that your wife's PET is negative!!

Well, my money is on an MRI, it took 12 months to diagnose my neck lymph gland, reverting back to scans and ultra sound to finally have the MRI pick it up, you could see the lump in my neck and feel it but the scans said there was nothing there. That wasn't my first time either it took 3 months to finally diagnose my fractured shoulder, X-Rays and a Bone Scan didn't pick it but the MRI did, I was worried that it was bone mets, I have also had an MRI on my heart so I don't have much faith in the scans anymore.

LOve & Hugs Lyn

I have CT/PET every 12 weeks & MRI to take a closer look at any suspicious spot that's popped up in my liver.I've come to understand that each type of scan, in combination is more reliable than any single one.
To make things even more confusing, my most recent CT showed a subcm, spot, the PET showed no activity, but 4 weeks later lots of activity.The Rad said the MRI looked like just necrotic tissue, but eventually went back to the PET & concurred that the spot is there.I'm scheduled for RFA next Friday.
As Rosie said, the CT will give you structural/size info, the PET will show level of metabollic activity, but won't give you measurements & the MRI can give you dimensions.I think of the 3 scans as layers of a photograph-CT gives you a black & white outline, the PET fills in the colors & the MRI gives you the 3D effect to give you a complete picture.
I tend to hold the PET info as the most important & relevant.
Hope this is helpful.

Thanks to all for your responses. Considering the good news the PET gave and all of your words, I'm happy to believe the PET!

Warmest regards,
Eric