TABLE 1
Summary of Characteristics of PET Radiotracers Relevant to α-Synuclein (Syn) Imaging
| Ligand | Structure | Affinity for α-synuclein fibrils (nM) | Affinity for Aβ1–42 fibrils (nM) | Binding to α-synuclein–positive human brain homogenates (nM) | Binding to Aβ-positive human brain homogenates (nM) |
| 11C-PIB (24,25) |  | Kd = 4* | Kd = 4.7† | DLB (Aβ+) brain homogenate: Kd = 5* | Binding to AD frontal cortex homogenate (11C-PIB): Kd = 1.4 |
| DLB (Aβ−), pure DLB: No significant binding* | Binding to AD brain homogenate (3H-PIB): Kd = 3.77* | ||||
| 18F-BF227 (20) |  | Kd = 9.63 | Kd1 = 1.31 | Failed to bind to DLB (Aβ−) homogenate | AD brain homogenate: Kd = 25 ± 0.5 |
| Kd2 = 80 | |||||
| 125I-SIL23 (23) |  | Kd = 148 | Kd (Aβ) = 635 | PD dementia brain homogenate: Kd = 119.1–168.3 | Not available |
| Kd (tau) = 230 |