PET Scans

About a month ago, as Papa and I were loading the kids into the car after work and talking about when Dave's next PET scan would happen, Ella asked me something to the extent of, "Does Daddy have pets?" I told her that he does not have any pets other than Georgia and Gypsy, and "PET" is the name of the test he has to do to see if his cancer is still gone.

She's my daughter, so she asked, "What does it mean?"
I said, "I'll tell you what it means. Are you ready?"
She nodded.
"Positron Emission Tomography." (Except I stumbled over the T word because I can never remember that.)
Her eyes glazed over, so I went on.
"It's a test where they give him special medicine, then roll him through a big scanner and watch how the medicine works in his body. If there is cancer in his body, they can see it when they scan him."
That seemed to be a satisfactory explanation for her.

Since then, I've answered that question from other people and a variety of other questions about the PET scan, so I thought I should blog about it.

Positron Emission Tomography - those are fancy words. It's a nuclear imaging test used to detect cancer (and other things, I'm sure, but primarily cancer). Some doctors poo-poo it, but oncologists believe it's golden - and for the price of it, it should be. It works like this.

The patient has to follow a no-carb diet for the last meal prior to the test (be it supper or breakfast, depending on test time), and eat/drink nothing but water for the five hours prior to the scan. It's not as horribly, hideous as fasting for a glucose tolerance test because you can still drink water (ahem), but nothing makes you want to eat a pile of noodles like being told you can't have carbs. Luckily, I just happened to walk by the calendar as I was cooking supper last night and noticed that the PET scan was scheduled for this morning, so I had to break the bad news to Dave that he couldn't eat the mac and cheese. His expression was positively combative as he demanded, "Why?!" I reminded him of the PET scan. He insisted he would be hungry if he couldn't eat the mac and cheese. I handed him a bowl of salad to go with his chicken and green beans. He finished the salad and said he wasn't hungry anymore. I packed a pile of mac and cheese for his lunch after the scan. Ordinarily, all of us would go carb-less on the night before the PET scan, but I honestly forgot this time.

Once he gets to the PET center this morning, he will be escorted to a little room with a sweet recliner. The tech will inject radioactive glucose into a vein in his hand or arm, and he'll kick back in the recliner for an hour to let the glucose move through his body. After an hour, he goes into the scan room, lies on the table, and gets scanned. That part takes about 45 minutes. I've only gotten a glance of the scanner because I'm not allowed in there, but he says it's like a CT scan but bigger.

The kind of scan he gets is actually a PET/CT combo, which is common. As the tech and the oncologist explained to us before the first one, the radioactive dye will "light up" when the body metabolizes the glucose, and cancer metabolizes it differently/faster than normal body tissue. They are watching to see what parts light up. There are parts of the body they expect to light up on the scan - like the brain and the heart - because of how they metabolize glucose, but they are looking for other parts that light up that would indicate cancer. They use the images collected in the scan and reconstruct 3D images of the body, then a radiologist reads the scan. It takes a few days to get the results.

Here's a picture of a whole body scan I found on Wikipedia, where you can read a lot more of the technical stuff about PET scans if you are a nerd like me.

That's basically it. It's a 2 hour process, and I think the hardest part for Dave is adhering to the diet.

Updated: The PET scan was clean and he graduated to the next phase of follow up care so he will start having scans every six months now instead of every three.