Table 1.

Current state of imaging biomarkers in the SCAs.

Brain imaging
MRI: brain volume changes
↓Cerebellum and brainstem volume in SCA1, SCA2, SCA3, SCA6, and SCA17 66 , 67 , 68
↓White matter and gray matter volume in cerebellum and brain stem in SCA1, SCA2, and SCA3 69 , 70 , 71 , 72
↓Spinal cord, basal ganglia, and cerebellar vermis size in SCA3 and SCA6 69 , 73
↓ Caudate size in SCA6 and SCA17 69 , 74
MRS: chemical changes
↓[Glu], [NAA], [NAAG], [tNAA], [Cho/Cr] ratio, and [Glu/Gln] ratio in SCA1, SCA2, SCA3, and SCA6 75 , 76 , 77 , 78
↑ [Glc], [Gln], [mI], [Tau], [tCr], and [Glc+Tau] in SCA1, SCA2, and SCA3 75 , 76 , 77 , 78
↓[GABA] in SCA6 41
↓ [NAA/Cho], [NAA/Cr] in SCA1, SCA2, SCA3, SCA6, and SCA17 75 , 76 , 77 , 78
PET: metabolic changes
[18F]FDG, [11C]dMP, and [11C]MP4P: ↓metabolism in different brain regions in SCA1, SCA2, SCA3, SCA6, and SCA17 81 , 82 , 83 , 84 , 85 , 86
SPECT: functional and metabolic changes
SCA2
[99mTc]TRODAT‐1 SPECT:↓striatal DAT binding 87
[123I]β‐CIT SPECT:↓striato‐cerebellar ratio 88
[123I]IBZM SPECT:↓striato‐frontal IBZM binding ratio 88
[123I]FP‐CIT SPECT:↓uptake in caudate and putamen 89
SCA3
[99mTc]TRODAT‐1 SPECT:↓nigrostriatal ratio 90
[99mTc]HMPAO SPECT:↓perfusion in cerebellar hemispheres, 91 inferior, 91 and superior 91 frontal lobe, 91 lateral temporal lobe, 91 parietal lobe, and vermis 91
[99mTc]ECD SPECT:↓perfusion in bilateral cerebellum 92 and vermis 92
[123I]iomazenil SPECT:↓binding in cerebellum, 93 cerebral cortex, 93 thalamus, 93 and striatum 93
SCA6
[99mTc]ECD SPECT:↓perfusion in cerebellar hemisphere 94 and cerebral vermis 94
SCA17
[99mTc]TRODAT‐1 SPECT:↓striatal DAT binding 87

Table is modified from Meng‐LingChen et al. ⁹⁵