@rdmiller
As I said before

With that low a PSA it is unlikely that a PSMA PET scan will find anything. It would be hard-pressed to find a doctor that would do it with a PSA that low. Your insurance company might not even want to pay for it.

With your PSA so low you don’t have a choice. The CT scan is the only one that will actually show anything.

While ALC might show aggressiveness of your underlying cancer, with your undetectable PSA. It’s unlikely to be changing.. Ask your doctor to run blood tests.