Comment by Moto7451

PET Scans feature areas with blood flow so tumors show up as hot spots for follow up. People who are maybe only feeling off or had one confirmed tumor can have a lot of small tumors spread across their body which will show up clearly on a PET scan.

When my brother was at the end of his run fighting cancer he felt a bit under the weather and managed to catch covid so everyone figured he was feeling bad due to that. The PET scan showed he had thousands of small masses converging into the large mass that eventually killed him by cutting off blood flow to his kidneys. His cancer was an aggressive blood cancer that had stood up to conventional and Trial Chemo drugs. There was no way to treat this but other cancers that are less aggressive can be treated at this point and would be treated differently than a single mass.

In a nutshell it’s that level of visibility that makes PET scans worth it.