PSMA PET-CT results

The way I understand it the PETPSMA scan combined with PSA test results give indicators of what’s going on with metastatic cancer. Unfortunately, you can have rising PSA (small values) and not see any new sites on a scan.
Thankfully, technicians are getting better at reading these scans and interpreting them and should be able to weigh in with some helpful information when comparing a current scan and a prior scan.

Good luck to you on your journey.

Yes, it's the SUV (Standard Uptake Values). Lower is better. If you are on antiandrogen the SUV could be nonexistant and the cancer still there, temporarily dormant. PSMA/PET is the best at detecting areas of low activity, though there can be false positives.
I hope you have luck.

As it turns out PSMA is not truly “prostate specific.” There are other organs, tissues, and fluids that express PSMA and will show as normal uptake (called “activity” or “avid” or “physiologic distribution of tracer”) in a PSMA PET scan - particularly in the lacrimal (tear) and parotid (saliva) glands, liver, blood, spleen, pancreas, ganglia; and also in the kidneys, ureters and the bladder (as the body tries to quickly excrete the radiotracer that was injected).

They use the SUVmax (the PSMA expression score) of your blood, liver, and parotid (saliva) for comparison purposes.

So, if PSMA is expressed by a lesion, and it has:
> a PSMA SUV score less than blood, then it’s not likely cancer, but instead just normal, background PSMA expression or something sclerotic;

> a PSMA SUV score greater than blood, but lower than liver, then it’s likely low-grade prostate cancer;

> a PSMA SUV score greater than liver, but lower than parotid glands, then it’s likely moderate-grade prostate cancer;

> a PSMA SUV score greater than parotid glands, then it’s likely high-grade prostate cancer;

So, the goal is to get the SUVmax of a lesion to less than blood.

Yes, I was just reading about how one scan (bone scan or PET, I can't remember) can falsely show increased cancer activity in your bones shortly after chemotherapy — whichever scan it was had trouble distinguishing between busy cancer cells growing tumours and busy healthy cells repairing bone.

Just some info. Technicians perform the scans; they don't interpret them. Radiologists (M.D.s who specialize in interpreting Imaging studies-MRI, CT, PET, US, plain x-rays, etc) interpret the PET scans. At some institutions other physicians trained in Nuclear Medicine also interpret PET scans.

I stand corrected! Thanks! 👍

This may or may not be relevant. Just before my proton radiation therapy of 2.5 months (2010) at Loma Linda, they performed a scan (I cannot recall either an MRI or PET). The radiologist noted calcifications around the various tissues of the prostate. The scan was used to determine the location of the cancer. That said, after almost 15 years, my PSA is beginning to increase. I had an MRI in early July of 2024 and it was noted by the radiologist the possibility of recurrence. Reviewing the plethora of information, it seems calcifications within the prostate are common and can sometimes viewed as cancerous. Therefore, the depth of experience at reading an MRI or other is very important.

This may not be relevant to the overall conversation, but the issue of prostate calcifications is often mentioned in medical journals reference prostate cancer, rising PSA, BPH (enlarged prostate) or others.