Tumor size differs between MRI, CT and PET

wdidg

My p16 scc tonsil tumor shows in different sizes in different scans. CT showed its 3.7cm. PET showed its 3cm and the recent MRI shows it’s 2.7cm. Anyone experienced this? Which one of these is more accurate?

wbcgaruss

I think you need to check with your doctors and have them verify the accuracy of these scans and explain the differences to you. It is possible since they are different types of scans that the read-out size is different but that your doctors know the scale of all three. I am just trying to figure out a reason, it does seem odd you would think the size would be the same no matter how it is scanned. The link below may shed some insight into it--

Measurements of tumor size using CT and PET compared to histopathological size in non-small cell lung cancer

https://pubmed.ncbi.nlm.nih.gov/23302288/

When you find out please let us know.

I did find this statement also--

The sizes of 102 tumors (80.3%) were larger on sonography than on CT/MRI. Twelve tumors (9.5%) were the same size and 13 (10.2%) were smaller on sonography than on CT/MRI. There was also difference in the tumor stage (very early or not) between CT/MRI and sonography (P= . 006, McNemar test).

From this article--

https://onlinelibrary.wiley.com/doi/abs/10.7863/ultra.32.10.1703

Take Care, May God Bless & Watch Over You

Russ

Quiet

I wouldn’t worry too much about the difference. I imagine the docs can use the readings as a baseline to see how the treatment is working if they do additional scans.

wdidg

Thank you Russ and Quiet.