Do cysts absorb radioactive glucose during PET/CT scan?

Portal Forums Cancer Basics Imaging Issues Do cysts absorb radioactive glucose during PET/CT scan?

This topic contains 4 replies, has 4 voices, and was last updated by  audreyainsworth 3 years ago.

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March 30, 2015 at 3:28 pm  #1269060    


A recent CT scan with contrast shows shrinkage of a Liver spot on the left lobe to 5 mm that had previously appeared as 20 mm on a PET/CT scan.

The jury is still out as to whether the spot is a cyst or a tumor, and so, shrinkage does not mean tumor responded to chemo vs. cyst may have shrunken on its own. (Biopsy could not be performed due to location under the lung.)

Would a cyst have appeared as a hot spot on a PET/CT scan at all–or only a tumor? Thanks!


PS Have requested a dedicated ultrasound of Liver to differentiate fluid-filled cyst from solid tumor. Hopefully an US will provide a definitive answer–but curious about the glucose absorption by a cyst.

DX 11/25/2014 Biopsy/diagnosis of anal cancer
PET/CT scan report: Stage 4 SSC of Anal Canal with mets to Liver (lymph nodes–inguinal and perianal)
TX 12/22/2014 through 2/2/2015 Chemoradiation (Nigro Protocol)
CT Scan with contrast 3/9/2015 showed 75% reduction (perianal lymph node involvement not shown)

March 31, 2015 at 7:34 am  #1269065    
JimC Forum Moderator
JimC Forum Moderator

HI Marianne,

Welcome to GRACE, and congratulations on the shrinkage of the liver nodule/cyst. A cyst can show up on a PET scan, but often with a lower level of uptake. That doesn’t definitively determine whether it’s a benign cyst or cancer, but the lower SUV does tip the balance a bit toward a benign finding.

Forum moderator

Jul 2008 Wife Liz (51/never smoker) Dx Stage IV NSCLC EGFR exon 19
4 cycles Carbo/alimta, 65% shrinkage
Tarceva maintenance
Mar 2010 progression, added Alimta, stable
Sep 2010 multiple brain mets, WBR
Oct 2010 large pericardial effusion, tamponade
Jan 2011 progression, start abraxane
Jun 2011-New liver, brain mets, add Tarceva
Oct 2011-Dx Leptomeningeal carcinomatosis; pulsed Tarceva
At rest Nov 4 2011
Since then:

March 31, 2015 at 9:05 am  #1269068    


Thanks, JIm!


August 5, 2015 at 2:05 am  #1270696    


August 6, 2015 at 5:07 am  #1270713    


PET/CT scan is an advanced nuclear imaging process that combines both into one machine. This machine has supplied by medical companies. It reveals details about cell and tissue’s structure and function in the body during a single imaging process. During this process, the patient is initially injected with a glucose solution, which has small level of radioactive material, absorbed by the exact organs or tissues being scan. It shows damaged or cancerous cells where the glucose are taken up and determine at what rate the tumor is using the glucose.

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