Tuesday, March 4, 2008

Mayo Clinic, Day 2

A Positron Emission Tomography (PET) scan employs a radioactive isotope which acts like a tiny lighthouse within the body. The body is transparent to this radioactive light (gamma rays), so the PET scanner can see it and can locate the isotope with precision. The isotope is attached to sugar (glucose) molecules, which are injected into the body and taken up in greater amounts by hungry cancer cells than by the body's other cells. Thus the scanner can see a lot of these tiny lighthouses wherever there are concentrations of cancer cells. In myeloma patients, the PET scan can spot hot spots capable of causing bone damage, before the damage is ever done.

PET scans are expensive, Sandy the nurse said $3500, and for myeloma patients they are not covered by Medicare. However, Medicare is currently funding a study of the usefulness of PET scans for myeloma, so scans are available to a Medicare patient if the patient's doctor is willing to do the paperwork required for the study. Happily, Dr. Lacy was not only willing but suggested the PET scan, for which I will always be grateful.

I was seated in a recliner chair, and Sandy first took a blood sample from a finger, and then injected the isotope (looked like clear water) into a vein. There was no sensation from the injection, except a slight, momentary coolness at the site. Then I sat for an hour, mostly dozing, to give time for the body to distribute the isotope to the organs that were most hungry for the glucose. During that hour I was instructed to be as still as possible, to avoid using muscles, because working muscles demand a refill of glucose, and we wanted as much of the glucose as possible to be free to go elsewhere.

Then I walked to the scanner and laid on a table in front of a big horizontal tube that looked like an MRI scanner, except larger in diameter and shorter in length. As with an MRI, the table scooted me in and out of the tube, but unlike an MRI it was almost silent. It was far less intimidating than a normal MRI. My arms were in an uncomfortable position over my head, or else I would have gone to sleep. The scan itself took about 30 minutes, after which I waited a few minutes more while they checked to see if they got what they wanted. I did ask the technician if there was anything that she could tell me, but she winked "that's what the doctors get the big bucks for."

For me, this seems like the big test. My blood tests have thus far always been negative for the other C.R.A.B. symptoms (organ damage), as have all of the x-rays, so this one is most likely the key test. Sunshine and I agree - whatever the answer, we want to know it, and treatment decisions will probably hinge on it. We'll know in a few days.

Recent lunch: Organic chard with pistachios and cranberries, organic vegetable mix with shredded asiago cheese, two clementines.


  1. Don, thanks for this report. I will have my second PET scan tomorrow!!! I'm followed in Bologna, not Florence like Margaret. My doc in Bologna requires the PET scan for his myeloma patients once a year, but in Florence they don't. I did not know that PET was so expensive. I know that the PET machines are incredibly expensive and that new research is demonstrating that PET scans are extremely useful with several kinds of cancer.
    Last year none told me not to move and stay as still as possible. Tomorrow I'll follow the Mayo advice, of course :-)
    However, last year I've been told other things that you do not mention. First, immediately after the PET scan you've to start drinking water, in order to eliminate the isotope from your body faster. Second, it's better you don't get too close to little babies for several hours.
    Tomorrow I'll check these points again.
    By the way, could you tell me exactly which kind of substance did they give you? This because
    '11C-Choline PET/CT appears to be more sensitive than 18F-FDG PET/CT for the detection of bony myelomatous lesions' (from a scientific article)
    One last point, my doc told me that it is better to also have a MRI, as PET alone will not tell you the whole story. He has written an article on this on Haematologica in 2007 (see http://www.ncbi.nlm.nih.gov/pubmed/17229635?ordinalpos=10&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum). If you are interested and give me an email address via Margaret I can send it to you.
    Ok for the moment it's all. I'll keep my fingers crossed for your results.
    Take care, Sherlock

  2. Hi Sherlock,

    Mayo actually was more concerned with the amount of water I drank BEFORE the PET scan, though I did make it a point to drink afterward too.

    I wasn't smart enough to ask which isotope I received, but it may be in the report and if not I'll try to remember to ask the doctor (if she knows). I know that the half-life of these isotopes is short, so availability is an issue, but perhaps not for Mayo.

    I suppose (hope) that Dr. Lacey will recommend an MRI if the PET scan suggests the need - we'll see.

    Thanks for the crossed fingers. :-)

  3. Hi Don,
    did they ask you to drink water before? And how much? Do you know why?
    All I've been told it that I do not have to eat anything in the 6 hours before the Pet. Considering that the Pet is scheduled at 11.30 am and that I usually feel very bad if I don't have brekfast by 8,30 I'll get up in the middle of the night and have a very early brekfast, say,at 4.30 am. :-)
    Keep us posted and super good luck!

  4. Very interesting posts, Don. I have never had a PET scan (as Sherlock pointed out) even though I asked my hematologist about having one last month. I admit to having a few reservations about swallowing radioactive sugar. But I would be curious to have this test done, so I will see if I can get my GP to request it for me at some point.
    All this information is very helpful, so thank you (and Sherlock) for sharing! :-)
    Florence, Italy

  5. Sherlock,

    Yes, they ask us to drink a liter and a half of water the day before the PET scan and 2/3 liter the morning of. They also require NO eating the morning of, and they ask that dinner the night before be low-carb (no pasta, bread, soda, etc), and no alcohol for 24 hours before. Trying to reduce the available blood glucose I believe.

    Right before they do the injection of the radioactive glucose, they also do a blood sugar measurement and the nurse said they would not proceed if it was too high.


    I'm a litte surprised that your onc won't order the PET. There is a little risk of course - you get as much radiation as two years worth of normal background radiation. I wonder if he just has a different view of the balance of risks.


  6. Wow! Different different different. I had my Pet this morning. None told me not to eat pasta and bread yesterday (which I did) and, as I told you, I was told to stay just 6 hours without food. Once there they asked me to drink only half a liter of water, immediately after the injection. However, the doctors were telling everybody they were 'radioactive' for a while. Therefore, we the radioactive people had separate restrooms and separate waiting rooms. I told them that a friend of mine at Mayo had been told to drink before and not after the examination. They replied that before or after was not important as it is to discard the excess of radioactive substance.
    For the rest the PET was like yours, Don. Half an hour (this time with arms down, last year was with arms up), very easy, much better than MRI.
    Last year, I was very disappointed by the kind of picture you get from the PET (not very detailed). I'm curious to hear about yours.

  7. There are a few new PET markers available that have slightly higher specificity to MM than the standard "glucose" uptake. They probably won't be clinically available for a while but it is encouraging that MM is getting such attention.

    • 11C-Methionine has been proven successful in bone marrow uptake for use in detection of multiple myeloma.

    • 35S-Methionine in the same study had a 5 to 6 fold increase in uptake in plasma cells.