Idiopathic Parkinson's disease (IPD) is the second most common neurodegenerative disease after Alzheimer's disease and it affects roughly 0.1% to 0.3% of the population. The risk of having IPD increases with age and the median onset age is about 60 years. The etiology of IPD remains unknown. Generally, Parkinson's patients show a reduction of dopamine levels in the deep grey matter of the brain over time. Many clinically diagnosed cases of IPD are associated with white matter hyperintensities (WMH) and elevated brain iron levels. Furthermore, in the last few years there has been an increasing interest in the role of veins in neurodegenerative diseases. More attention has been paid to the extracranial veins as being potential sources of venous hypertension. The obstructed veins are thought to cause venous insufficiency. By using MRI techniques, the investigators can not only obtain qualitative vascular information but also quantitative arterial and venous blood flow measurements.