Figure 6. Molecular imaging of dopaminergic dysfunction in Parkinson's disease (PD) involves the use of PET (positron emission tomography) and SPECT (single-photon emission computed tomography) imaging techniques. In PD patients, these imaging studies reveal a reduction in VMAT2 (type 2 vesicular monoamine transporter) activity, DAT (dopamine transporter) availability, and DDC (dopa decarboxylase) activity when compared to healthy individuals used as controls. PET and SPECT imaging provides valuable insights into the molecular changes associated with PD, showcasing lower levels of VMAT2, DAT, and DDC functions, which are indicative of dopaminergic dysfunction in the disease [48].