Table 3.
Outlines the range of imaging biomarkers and their potential relevance to clinical trial design
| Imaging modality | Differentiating PD from healthy controls | Marker of disease severity | Differentiating PD from atypical parkinsonian disorders | Predicting disease progression | Surrogate for disease progression |
|---|---|---|---|---|---|
| Transcranial sonography | + | − | + | – | − |
| T1-weighted structural MRI | ++ | +++ | +++ | ++ | +++ |
| Neuromelanin MRI | + | + | + | – | ++ |
| Iron sensitive MRI | +++ | + | ++ | + | +++ |
| Diffusion MRI | +++ | ++ | ++ | ++ | ++ |
| MR spectroscopy | +++ | ++ | ++ | – | – |
| Functional MRI | ++ | – | + | – | + |
| PET/SPECT | |||||
| Radionuclide | – | – | – | – | – |
| α-Syn | − | − | − | – | – |
| Dopaminergic | +++ | +++ | − | − | +++ |
| Non-dopaminergic | ++ | ++ | – | ++ | – |
| Synaptic density | ++ | + | – | – | − |
| Metabolic and network imaging | |||||
| Glucose metabolism | +++ | + | ++ | ++ | + |
| Neuroinflammation | + | + | − | – | – |
PD = Parkinson’s disease; SPECT = single-photon emission computed tomography. Grading approach adapted from Majbour et al.20
− = No effect (also scored if negative in a meta-analysis).
+ = Effect 1 study/inconsistent results across studies.
++ = Effect in 2–3 studies using single site cohort.
+++ = Effect in ≥3 studies or multisite cohort (also scored if positive in meta-analysis).