Rosemary
                    
                    
                    
                    
                    
                    
                    
                        
                        
                        I had one done, they numb the area and then it is pretty much like  an MRI.  Be sure that you are not allergic to shellfish, the basis for the dye  and have someone to drive you home.  Heat or ice afterwards helps.  It really was   an excellent diagnostic tool for me and let  the neurosurgeon see exactly what was wrong and how to fix it.    Good luck.