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Posts: 168
Joined: Feb 2005

Can someone explain exactly what the procedure is for a Pet Scan and exactly what it shows. Thanks, my mom is having one on Tuesday.

Posts: 6
Joined: Feb 2004

I just had a PET scan on Thursday, and it was very easy and noninvasive. I was told to be on a low carb Atkins-type diet for 24 hours in advance of the procedure. You cannot have anything to eat or drink (except water) six hours before the procedure; you may take medication which does not have to be taken with food. The process begins with an injection of glucose that contains a harmless, low-level radioactive tracer. I then had to wait 45 minutes for the solution to travel throughout my body. They then scanned my body from my knees to my eyes taking about 40 minutes; I then had to wait another 40 minutes; and they did another scan lasting about 15 minutes. I was there for about 3 hours.

The good thing was at least it didn't involve drinking anything! Good luck--hope all turns out well.

Posts: 168
Joined: Feb 2005

What does it show? She hasn't had chemo yet and we know where the cancer is from a cat scan.

spongebob's picture
Posts: 2599
Joined: Apr 2003

themis01 -

The CT scan will show cancer, but it will cannot differentiate between living cancer and dead cancer. What the PET scan does is first, with the 24 hour diet, you starve the body of sugar - cancer eats sugar. Then after the cancer cells are good and hungry for some sugar, the PET scan injects sugar marked with a radioactive isotope. The living cancer cells will gobble-up the "hot" sugar and the docs will be able to see where the living cancer cells are located. That's what makes the PET scan a... I hate to say "more valuable" diagnostic tool, but it is certainly another good diagnostic tool to be used in not only "seeing the cancer", but also in knowing which cancer cells are still alive and need to be zapped.

Hope that's helpful

- SpongeBob

Moesimo's picture
Posts: 1079
Joined: Aug 2003

A pet scan is used to detect any cancer. It will show where the cancer is and also if there is any spread. It can pick up tumors that are not seen on a cat scan. It is good to do when first diagnosed as a baseline and should be repeated yearly or sooner if any other test shows that the cancer could have spread.

Good luck, Maureen

Posts: 835
Joined: Apr 2004

Great replies aboove- I esp like SBs descriptions (couldn't put it better myself). Just wanted to add that you do need to be cautious of the scans results. I wouldn't entirely agree with Maureen here that it is good to do it at baseline and repeated yearly and that is certainly not somehting that all docs do.

It does have the problem of missing some cancers and also of showing some sites that are active and not cancer. In otherwords it is not a prefect test which is why many docs don't use it. In some case it is a useful addition to CT because CT looks at structure (like a traditional xray) where as PET scans look at function ie looks for bunches of cells in tehe body that are abnormally over active (like cancer cells). Putting the two results together gives a good idea of where the cancer is and informs decisions about how to treat it. It is especially used if the CT shows suspicious structures that aren't 100% clear as to whether they are cancer or not. Furhtermore some docs just feel they are useful for looking for sites in teh liver and lung as well as other distant bits of the body.
There have been previous discussions on this site about PET scans and there are some who worry they aren't being offered them. Hence I justwanted to added this info to explain why your mom may be having one while others don't.
Hope I haven't just confused you further,

Posts: 768
Joined: Aug 2004

Nice explanation Steve. I just had my PET/CAT this morning. Mine was a combined scan which shows both the function (PET) and structure (CAT)on the same films.

Just waiting for results.

As the others have said it is a non invasive, fairly simple test. I only had to stop eating 12 hours before the test.

Good luck. Get a copy of the films, they are quite amazing.


jsabol's picture
Posts: 1156
Joined: Dec 2003

Hi, Lots of good info here from all the responders. Just wanted to add a clarifying statement to SB's info (sorry Bob)....cancer eats "sugar" (glucose) as all cells do. Glucose is the end product of breaking down many of the foods we eat, even "healthy" carbs like fruits, veggies and grains. As Steve said, cancer cells are overactive, so they take up "sugar" more quickly than other cells, allowing the PET scan to highlight those areas of extra activity. One common problem is that there can be other reasons for increased cell activity, such as infections, so there may be some false alarms raised. Some docs seem to use or recommend PET scans more than others?? My onc recommends yearly unless there are other suspicious signs/symptoms that we need to investigate further.
Good luck to you and mom. Judy

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