To add to this, I had an appointment with my neurologist today and she said she just recently discussed the PET-CT and MRI results with the NYU Langone doctor who arranged them. Both are in agreement that I seem to have entered a stable period in which a daily dose of 20mg Prednisone is serving me well. They are both inclined to keep me on this, given my current condition, my age, my medical history, etc, but will try something else if new symptoms develop or the stability goes away. I am quite content with this, although it does mean accepting that what has caused my demyelination disease remains a mystery.

Don