Study duration is expected to be completed in a period of 4 year. This study will compare the microstructural integrity by multimodal MRI imaging and monoaminergic function by18F- DTBZ PET in 35 PD patients without dementia/ICD (PD group), 35 patients with mild cognitive impairment (PD-MCI), 35 PD patients with dementia (PDD group), and 35 patients with impulse control disorders (PD-ICD group).