PET Scan

lisabnc
lisabnc Member Posts: 1
edited March 2014 in Colorectal Cancer #1
Does anyone know why you have to follow a low carb diet on the day before your PET scan? I have one tomorrow and they said low carb, no gum, no hard candy, no excercise of any kind the day before on my paper...just curious.. Thanks in advance!

Comments

  • vinny3
    vinny3 Member Posts: 928 Member
    #2
    For the PET scan they feed you some radioactive-tagged sugar. The idea is that cells that metabolize at a faster rate (such as cancer cells but also recent healing surgery sites) will take more in and thus "light up". If you load up those cells ahead of time they may not take as much and would not light up. Prohibiting the exercise may be so that you don't injure a muscle or area of the body as that could make that area light up as well.

    ****
  • KathiM
    KathiM Member Posts: 8,028 Member
    #3
    vinny3 said:

    For the PET scan they feed you some radioactive-tagged sugar. The idea is that cells that metabolize at a faster rate (such as cancer cells but also recent healing surgery sites) will take more in and thus "light up". If you load up those cells ahead of time they may not take as much and would not light up. Prohibiting the exercise may be so that you don't injure a muscle or area of the body as that could make that area light up as well.

    ****

    I LOVE our 'resident doctor'!!!! You explain things so well, ****....thank you!

    Hugs, kathi
  • Betsydoglover
    Betsydoglover Member Posts: 1,248 Member
    #4
    vinny3 said:

    For the PET scan they feed you some radioactive-tagged sugar. The idea is that cells that metabolize at a faster rate (such as cancer cells but also recent healing surgery sites) will take more in and thus "light up". If you load up those cells ahead of time they may not take as much and would not light up. Prohibiting the exercise may be so that you don't injure a muscle or area of the body as that could make that area light up as well.

    ****

    Hi -
    I also read / was told that any muscle activity, even without injury can show up on PET. In particular, heavy exercise can result in increased uptake in the heart, making it difficult to detect any lesions that may exist near the heart. Apparently, caffeine can also cause this effect because it increases heart rate. I always have my PET's in the mid morning and refrain from any food after about 7PM the previous evening, while eating "moderately" the previous day - good mix of carbs/protein - relatively low glycemic load eating. The idea is to make sure your blood glucose levels are not high, so that any cancer cells uptake the radioactive glucose and not the excess you just consumed yesterday.

    False positives with PETs may be disturbing, but false negatives are way worse - so the low activity, low carb day before the scan helps to ensure more reliable results.

    Take care,
    Betsy
  • hopefulone
    hopefulone Member Posts: 1,043 Member
    #5
    This is why I am so grateful for this site. Someone always has information to share. I wasn't aware of this and I don't believe my hubby did any "fasting" before his PET when we first started this battle. I'm sure he will be having a PET again in the future, so thanks for asking the question and thanks to those knowledgeable folks out there for the answer! God Bless and I wish you an all clear on the scan. Keep us posted.
    Diane

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