I couldn’t remember if I ever explained in details what a PET Scan (or PT Scan) really is, and it’s one of the more interesting tests that I’ve undergone during my treatment. And since I’m WAY to lazy to use the little search box over there and figure it out, and I need something to blog about for today, I’ll fill you in (possibly again).

pic from Wikipedia

PET (or positron emission tomography, if you will) Scan is a form of nuclear medicine that is in many ways similar to a CT Scan. The machines look the same, they serve the same general function (lookin’ at yer insides) and in fact a CT Scan is often done in conjunction with a PET Scan. That was the case when I had my PET Scan on Thursday.

The hospital we go to doesn’t have its own PET Scan machine so they contract out to a mobile unit that travels between various hospitals in the area. So on the day on the test we checked in at the radiology imaging desk and then they took me down a long hallway and out the back into their large trailer with no windows that was parked out on the loading dock… totally normal … right? =)

Once in the trailer they started an IV and injected me with a small amount of radioactive glucose (sugar water). Cancer cells are highly metabolic, much more so than most of the normal cells in the body, so the idea is that these cancer cells will be the first to be able to make use of any food entering the body (in this case glucose). The scanner then looks for the radioactive isotopes that the cancer cells were “tricked” into absorbing and HUZZAH! you have image of all the cancer in your body. Or in my case now LACK THEREOF! Seeing the final image is actually kind of cool because the tumors show up as almost glowing in the pictures that these machines create (as they did when I last had the test back in October).

Once injected though, you have to wait. They leave you in a little room, and ask that you lay still in the dark for about 20 minutes before the scan can occur (again, I just go with it and trust that its normal). This gives the body (or tumors) a chance to absorb the radioactive glucose. Laying still in the dark ensures that you are doing no work, otherwise various muscle groups could be the first to absorb the glucose. They told me the last time I had the test that if they were to leave me with a magazine or anything to read, that the results would come back showing my hands, arms, and eyes glowing.

After 20 minutes in the fortress of solitude, I was taken to the bathroom and encouraged to try and empty my bladder if at all possible. It helps with pictures and keeps the bladder from absorbing too much radiation.

The test itself takes about another 20 to 30 minutes. They lay you on the board and move you through the machine slowly taking long 3 minute exposures before moving you a few inches and taking another picture. The only uncomfortable part is that you have to keep your arms up above your head so they are out of the way, and that can start to feel strained after a while. And really its not as bad as the 40+ minute MRI where you’re in the same position but for longer.

In the end, they pull you out, tell you put your pants back on (I swear the whole thing is not as creepy as it has sounded) give you a little slip of paper and send you your way. The paper is a document indicating that you’ve have a nuclear medicine procedure and that you will be a bit on the radioactive side for a day or two. Apparently you can be can be detected at airports or on ferries if you are radioactive and this basically says why are you radioactive and that you’re safe. Kind of crazy to think about.

Overall its a very effective test, but is more expensive and subjects you to a much higher dose of radiation than a CT Scan so the CT Scan is used more frequently, and the PET Scan called in only when the CT isn’t conclusive any more. As was the case for me. The CT scans were showing that the tumor in my chest wasn’t shrinking any more, and as it turned out it was because what remains is only scar tissue, because, and lets say it together:

Great News!!
PET scan normal with no evidence of Hodgkins disease