The FDG PET scan is looking for metabolism in the brain. They look for two things. Active glucose metabolism and also areas where there is reduced or no active glucose metabolism. Apparently, there is an increase in metabolism in your basal ganglia but normal metabolism elsewhere.

The FDG stands for FluoroDeoxyGlucose. It gives off an imageable signal as it is metabolized.

So, yes, you do have normal blood flow to your head. The FDG PET would not tell why you have a change in blood flow when you first stand up.