• Which test is most accurate to detect spread of cancer, CT Scan or PET/CT Scan?

    Asked by queen on Monday, February 18, 2013

    Which test is most accurate to detect spread of cancer, CT Scan or PET/CT Scan?

    1 Answer from the Community

    • jdub54's Avatar

      It all depends.....my primary oncologist wants the PET (positron emission tomography), which actually images the hyper-metabolic activity of a tumor. My secondary oncologist (and chief of melanoma at Memorial Sloan Kettering in Manhattan NYC) wants CTs (CT is computed tomography, CAT computed axial tomography); I figure he knows what a tumor looks like via CT (without the measure of metabolic activity). Neither is wrong, and I actually am in the watchful monitoring phase, and alternate 1/4ly between the 2 Docs and their differing approaches; I figure this gets me the best overall monitoring. And extremely rigid monitoring to catch any new metastasis early is the key to fast surgical removal and life extension with my rare cancer. Insurance company hates to authorize the expensive PETs, but too bad for them, we ultimately get it approved after much wrangling. Neither is perfect, and the risks to patient are different between them. With the CT you get more xray dosage and the risks from that, but modern CTs are reduced 50% in dosage from just a decade ago. The CT actually images the unusual density/anomalous location/patterns of tumor tissues. The contrast agent for a CT may have an allergy issue for those allergic to shellfish or who have had bad reactions to iodine related items in the past.. PET uses minimal CT/xray for correlation purposes only (the "matrix" the PET image gets built ontop of), and a radioactive isotope in the injected dose to image with. Isotope has very short half life. The "hot" tumor is hungry and digests food fast, it eats the isotope-infused sugar compound faster than healthy cells, and thus the concentration of positron emissions "paints" an image if tumor is present (thus the fasting and minimized activity requirements before a PET, so healthy cells have not been at full metabolic activity and .don't suck up the isotope overly quickly, resulting in false hot spots) Trust the choice of the doctors you trust most. Both mine have their (different) reasons, and their own skill sets. I'm still here, so it's working!

      over 3 years ago

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