Three phase nuclear bone scans used to considered diagnostic criteria to confirm CRPS/RSD. Some still consider them diagnostic. It often depends on the stage of the disease as to whether they will be consistent with a diagnosis of RSD. As in, sometimes later in the disease they become normal again. So they are more useful early on like six months or less. However, I had one 10 months from onset of symptoms that was consistent with CRPS type 1 in my right leg and considered diagnostic.