English please for medical terms on PET report - 1262527

lmlb7665
Posts:48

Dr West:

I have a few questions that deal with trying to understand terminology on a PET/CT report. I am NOT asking for a diagnostic opinion. (I know you do not do that).

1. What does "mildly hypermetabolic with a peak SUV 2.8 " mean. Second, is there a range of uptake? In other words is this a scale of 0-10?

2. What is "low FDG avidity"?

And then if an identified lesion was .4cm (5-24-11) then 1.4 (11-24-13) and now 1.6 (2-24-14), is this slow or fast growth?

As always, thank you for all you do us so that we can understand our disease and care.

Respectfully,
Louise

PS. I think my bio should follow. I have not asked a question for sometime.

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Reply # - February 27, 2014, 02:32 PM

JimC
Posts: 2753

Hi Louise,

PET scans measure how much of a glucose-based tracer substance is concentrated in the body. Areas of cancer will cause this to happen, but so will other conditions such as inflammation or infection. The SUV is a numerical measure of that uptake, and there is no range such as 0-10. Your uptake of 2.8 is pretty low, which is why the report suggests that the activity in that spot is only mildly "hyperactive" (there's more going on there than normal). "Low FDG avidity" means the same thing as a low SUV - FDG is the tracer substance, and "FDG avid" just means an area has taken up some of that tracer, but not to a great extent. As Dr. West said in his post "Cancer 101 FAQ: Primer on PET Scans":

"There is no threshold SUV number that distinguishes cancer from inflammation or infection, but higher numbers (especially in the high single digits or more) are most suggestive of cancer." - http://cancergrace.org/topic/english-please-for-medical-terms-on-pet-re…

That's pretty slow growth, especially in that last 3 months. A difference of 0.2 cm is small enough to represent only the difference between two PET machines or in how the images "slice".

JimC
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Reply # - February 27, 2014, 04:22 PM

dbrock
Posts: 162

Operations Director, GRACE

 

Hi there! I believe the link is http://cancergrace.org/cancer-101/2010/09/14/cancer-101-faq-primer-on-pet-scans/ for the Cancer 101, primer on pet scans. :)

Operations Director for GRACE. Have worked with cancerGRACE.org since July 2009.  Became involved as a caregiver to my best friend, and quickly came to see that GRACE is filling a need in the area of cancer education. 

Reply # - February 28, 2014, 12:40 PM

carrigallen
Posts: 194
Second, is there a range of uptake? In other words is this a scale of 0-10?

This is why we do not routinely use PET/CT to monitor lesions over time. There is no real SUV 'range', and it is not a universally standardized measure. There can be substantial variation in SUV during the day, between patients, and between days, depending on the technician, the patient's diet, the machine itself, the tracer, etc. PET/CT does a slipshod job of actually measuring tumor size, whereas plain CT measures size more accurately.

The other problem is that unless a lesion is visible by plain CT, it usually cannot be biopsied anyway.

Guidelines have strongly advised against using PET/CT for routine surveillance of cancer lesions. PET/CT also costs 10x more than regular CT. There is often misalignment of incentive with practices that own their PET/CT, so this problem is pervasive.

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