Table 5.
Summary of neuroimaging findings in tauopathies.
| Disorder, neuroimaging modality | Brief summary of findingsa | References |
|---|---|---|
| Progressive supranuclear palsy | ||
| • Structural MRI | MRI signs: hummingbird sign, morning glory sign ↓ in midbrain and SCP vs. PD, MSA-P, CBD/CBS, and NC ↓ in brainstem and gray matter of frontal lobe vs. NC Magnetic resonance parkinsonism index: ratios of pons-to-midbrain area and MCP-to-SCP widths were ↑ in PSP vs. PD, MSA-P and NC. The revised version of index incorporates third ventricle width and frontal horns width |
(121–129, 131, 132, 136) |
| • DWI/DTI MRI | ↑D and ↓ FA in multiple regions including midbrain, SCP, orbitofrontal white matter, thalamus, motor and SMA vs. NC ↑D in the decussation of SCP vs. MSA and PD ↑ ADC in putamen, globus pallidus, and caudate nucleus vs. PD ↓ FA in SCP in PSP-RS vs. PSP-parkinsonism ↑ free water in posterior SN vs. MSA, PD and NC; ↑ free water-corrected FA in caudate nucleus, putamen, thalamus and vermis and ↓ in SCP and corpus callosum vs. NC |
(66, 115, 118, 132, 139–142, 145–147) |
| • Proton MRS | ↓ NAA/Cr ratio in LN, brainstem, centrum semiovale, frontal, and precentral cortex vs. NC ↓ NAA/choline ratio in LN vs. NC; ↓ NAA/Cr ratio in putamen vs. PD and MSA ↓ cerebellar NAA/Cr and NAA/myo-inositol ratios in PSP-RS vs. NC, and ↓ cerebellar NAA/Cr ratio in PSP-RS vs. PD |
(77, 148–150) |
| • PET and SPECTb |
Dopaminergic system:
b ↓ striatal presynaptic DAT binding, with ↑ but fairly uniform DAT loss in striatum vs. PD ↓ dopamine D2 receptor binding vs. NC |
(200, 204, 229, 230, 239, 242) |
| Glucose metabolism: PSP-related spatial covariance pattern may show hypometabolism in brainstem and mediofrontal cortex | (273, 279) | |
|
Tau: ↑ binding in putamen, pallidum, thalamus, midbrain, cerebellar dentate nucleus, and basal ganglia vs. NC ↑ binding in globus pallidus, midbrain, and subthalamus in PSP vs. PD |
(297–301, 303, 304) | |
| Neuroinflammation: ↑ microglial activity in basal ganglia, midbrain, frontal lobe, and cerebellum vs. NC | (324) | |
| Corticobasal degeneration/syndrome | ||
| • Structural MRI | Atrophy patterns align with the “true” underlying pathology The predominant clinical syndrome in CBS relates closely to regional atrophy patterns In general, asymmetric cortical atrophy in frontoparietal lobe contralateral to more affected side in CBD/CBS vs. NC ↓ in bilateral premotor cortex, superior parietal lobules, and striatum in CBS vs. NC ↓ in dorsofrontal and parietal cortex and ↑ global brain atrophy in CBS vs. PSP; ↓ in midbrain in PSP vs. CBS |
(6, 121, 123, 129, 152, 153, 155, 156) |
| • DWI/DTI MRI | ↑D and ↓ FA in posterior truncus of corpus callosum in CBS vs. PD and NC ↓ FA in long frontoparietal connecting tracts, intraparietal associative fibers, corpus callosum, and sensorimotor cortical projections in CBS vs. NC |
(59, 152, 158) |
| • Proton MRS | ↓ NAA/Choline and NAA/Cr ratios in contralateral frontoparietal cortex, LN and centrum semiovale in CBS vs. NC ↓ NAA/Cr ratio in frontal cortex and asymmetrically in putamen in CBS vs. PD, MSA and vascular parkinsonism |
(149, 150, 159) |
| • PET and SPECT b | Glucose metabolism: CBS-related spatial covariance pattern may show asymmetric, bilateral hypometabolism involving frontal and parietal cortex, thalamus, and caudate nucleus, with ↑ abnormalities contralaterally | (267) |
| Dopaminergic system: b ↓ striatal presynaptic DAT binding with hemispheric asymmetry vs. PD. | (226, 227) | |
| Tau: ↑ asymmetric binding contralateral to the clinically affected side in putamen, globus pallidus, thalamus, and midbrain vs. NC, and in motor cortex, corticospinal tract, and basal ganglia vs. AD and PSP | (306, 307) | |
| Neuroinflammation: ↑ microglial activity in caudate nucleus, putamen, SN, pons, pre- and post-central gyrus and frontal lobe vs. NC | (334) | |
AD, Alzheimer's disease; ADC, apparent diffusion coefficient; APOE-ε4, apolipoprotein E ε4-allele; CBD, corticobasal degeneration; CBS, corticobasal syndrome; NC, normal controls; Cr, creatine; D, mean diffusivity; DAT, dopamine transporter; DWI/DTI, diffusion-weighted and diffusion tensor imaging; FA, fractional anisotropy; LN, lentiform nucleus; MCP, middle cerebellar peduncle; MRI, magnetic resonance imaging; MRS, magnetic resonance spectroscopy; MSA, multiple system atrophy; MSA-P, MSA-parkinsonian type; NAA, N-acetyl aspartate; PD, Parkinson's disease; PET, positron emission tomography; PSP, progressive supranuclear palsy; PSP-RS, PSP-Richardson's syndrome; SCP, superior cerebellar peduncle; SMA, supplementary motor area; SN, substantia nigra; SPECT, single photon emission computed tomography. a = not all findings discussed in the review are presented; please refer to relevant sections of the review for full details. b = readers are referred to Table 3 in Saeed et al. (10) for further comparisons of SPECT, PET, and transcranial sonography findings in Parkinson's disease vs. atypical Parkinsonian syndromes.