Table 3.

PET imaging studies assessing TSPO tracers in Huntington’s disease.

Population	Radioligand	Main Findings	References
11 manifest HD patients vs. 10 HC	11C-PK11195	Significantly increased tracer BPND in striatum, pallidum, frontal and parietal cortical areas in HD group Significant correlation between striatal 11C-PK11195 BPND and motor symptoms severity	Pavese et al. (2006) [85]
11 premanifest HD patients vs. 10 HC	11C-PK11195	Striatal and cortical (frontal, parietal, temporal, occipital) tracer BPND greater in HD patients than in healthy subjects	Tai et al. (2007) [86]
10 premanifest HD patients, 9 manifest HD patients and 10 HC	11C-PK11195	Tracer uptake is significantly higher in hypothalamus and striatum in premanifest and manifest HD than in healthy volunteers No significant difference in binding between premanifest and manifest HD No significant relationship between motor symptoms and 11C-PK11195 BPND in hypothalamus	Politis et al. (2008) [87]
8 premanifest HD patients, 8 manifest HD patients and 16 HC	11C-PK11195	In premanifest patients, significantly increased BPND radioligand in cognitive regions compared to normal controls Same results for symptomatic HD, with additional increases in pallidum, anterior prefrontal cortex and limbic striatum	Politis et al. (2011) [88]
12 premanifest HD patients vs. 12 HC	11C-PK11195	Significant increases in BPND radioligand in striatum, pallidum, thalamus and precentral gyrus in premanifest HD patients versus healthy controls	Politis et al. (2015) [89]

BP_ND, binding potential; HD, Huntington’s disease; HC, healthy control.