Just like with most every other test/scan for prostate cancer - PSA, MRI (PIRADS), biopsy (Gleason), Decipher (decipher score), etc. - a PSMA PET scan always results in a “SUVmax” score, which indicates the aggressiveness of every instance of tracer binding activity they see.

You mentioned that they noted “tracer binding activity in both central lobes of prostate.” They should have then indicated SUVmax scores for both of those. (If not, you should ask what those SUVmax scores of tracer binding activity were.)

Here’s a (very lengthy) explanation of how they use the SUVmax scores to determine cancer location and aggressiveness:

As it turns out, PSMA (prostate specific membrane antigen) is not really “prostate specific.” There are other organs, tissues, and fluids that naturally express PSMA (without being cancerous) and will show as tracer uptake on a PSMA PET scan - particularly in the lacrimal (tear) and parotid (salivary) glands, blood, liver, spleen, pancreas, ganglia, and more, as well as the kidneys, ureters and the bladder (as the body tries to quickly excrete the radioligand that was injected).

“SUV” stands for “standard uptake value” and is a measure of radiotracer uptake that indicates how high grade the cancer is. The higher the SUVmax, the more advanced the cancer.

They use the PSMA SUVmax values of your blood (the lowest level), liver (the medium level), and parotid or the lacrimal glands (the highest level) of SUVmax tracer binding expression for comparison.

If a suspicious area (lesion) is expressing PSMA, and it has:
> a PSMA SUV score less than blood, then it’s not likely cancer, but instead just normal, background PSMA cellular expression;

> 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 lacrimal/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;

That PSMA PET information - in addition to PSA, MRI, biopsy, decipher, etc. information - helps guide them in developing the appropriate treatment for your specific disease.

As always, discuss all this with your doctor when you get your SUVmax scores from them for your PSMA PET scan report.