Flow quantification (FQ): Pathological change in cerebrospinal venous drainage will be reflected by upstream disturbance of venous flow. Phase contrast MR flow techniques allow the investigators to interrogate venous flow. By applying FQ techniques to the dural venous sinuses, investigators hope to characterize the interplay between anatomic venous obstruction and pathologically altered drainage. By understanding this relationship, the investigators can gain deeper insight into the mechanism by which cerebrospinal venous insufficiency interacts with iron homeostasis mechanisms and ultimately with the pathogenesis of Parkinson's disease. Dural sinus hemodynamics can be studied non-invasively with phase contrast FQ. The phase contrast flow quantification (PCFQ) images will be used to analyze the through-plane cerebral spinal fluid in the neck (C2/C3 level), as well as blood flow in the neck (C2/C3 and C6/C7 levels), the superior sagittal sinus (SSS), both left and right transverse sinus, the straight sinus, both the extra cranial jugular and vertebral veins and Dural Sinus. Areas of interest will be drawn around the veins and arteries of interest and flow will be calculated over a full cardiac cycle. Thirty time points will be collected for each cardiac cycle by using a retroactive pulse trigger. The vessels of interest will include: the internal and external jugular veins (IJVs, EJVs), vertebral veins, deep cervical veins, common carotid arteries and vertebral arteries. The investigators will be evaluating the integrated flow, the average velocity, the volume flow rate, as well as negative and positive flow rate. This will be assessed in the cervical arteries to compare the inflow and outflow of the brain. Abnormalities may be identified by stressing the system, i.e., with a breath hold. Finally a large number of quantitative measures will be made on all the arteries and veins in the neck to assess both individual variants and total flow in the brain.