TSPO PET Imaging for Neuroinflammation

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TSPO PET Imaging for Neuroinflammation

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TSPO PET Imaging for Neuroinflammation

Overview

Translocator Protein (TSPO) Positron Emission Tomography (PET) imaging is a powerful in vivo technique for visualizing and quantifying neuroinflammation in the living human brain. Originally known as the Peripheral Benzodiazepine Receptor (PBR), TSPO is an 18 kDa transmembrane protein located primarily on the outer mitochondrial membrane of [microglia](/cell-types/microglia-neuroinflammation), the resident immune cells of the central nervous system [1](https://pubmed.ncbi.nlm.nih.gov/28459611/). Following activation of microglia in response to neuronal injury, infection, or disease processes, TSPO expression increases substantially, making it a sensitive biomarker for detecting neuroinflammatory processes in neurodegenerative diseases [2](https://pubmed.ncbi.nlm.nih.gov/23274174/). [@tspo2017]

This mechanism page provides a comprehensive overview of TSPO biology, the development of PET radiotracers targeting TSPO, clinical applications in Alzheimer's Disease (AD), Parkinson's Disease (PD), Amyotrophic Lateral Sclerosis (ALS), Frontotemporal Dementia (FTD), and Multiple Sclerosis (MS), as well as technical considerations and future directions for therapeutic monitoring. [@pet2013]

TSPO Biology and Role in Neuroinflammation

Molecular Characterization

...

TSPO PET Imaging for Neuroinflammation

Overview

Translocator Protein (TSPO) Positron Emission Tomography (PET) imaging is a powerful in vivo technique for visualizing and quantifying neuroinflammation in the living human brain. Originally known as the Peripheral Benzodiazepine Receptor (PBR), TSPO is an 18 kDa transmembrane protein located primarily on the outer mitochondrial membrane of [microglia](/cell-types/microglia-neuroinflammation), the resident immune cells of the central nervous system [1](https://pubmed.ncbi.nlm.nih.gov/28459611/). Following activation of microglia in response to neuronal injury, infection, or disease processes, TSPO expression increases substantially, making it a sensitive biomarker for detecting neuroinflammatory processes in neurodegenerative diseases [2](https://pubmed.ncbi.nlm.nih.gov/23274174/). [@tspo2017]

This mechanism page provides a comprehensive overview of TSPO biology, the development of PET radiotracers targeting TSPO, clinical applications in Alzheimer's Disease (AD), Parkinson's Disease (PD), Amyotrophic Lateral Sclerosis (ALS), Frontotemporal Dementia (FTD), and Multiple Sclerosis (MS), as well as technical considerations and future directions for therapeutic monitoring. [@pet2013]

TSPO Biology and Role in Neuroinflammation

Molecular Characterization

The translocator protein (TSPO) is encoded by the TSPO gene (also known as PBR) located on chromosome 22q13.3 [3](https://pubmed.ncbi.nlm.nih.gov/21606672/). TSPO is highly conserved across species and is expressed ubiquitously in peripheral tissues including kidney, heart, lung, and adrenal glands, as well as in the brain where it is predominantly expressed by microglia [4](https://pubmed.ncbi.nlm.nih.gov/22951353/). Under physiological conditions, TSPO is present at low levels in the healthy brain, with baseline expression primarily restricted to microglia with minimal neuronal expression. [@tspo2012]

The protein functions as part of a complex that includes the voltage-dependent anion channel (VDAC) and the adenine nucleotide translocase (ANT) on the mitochondrial membrane, playing roles in cholesterol transport, heme synthesis, cell proliferation, and [apoptosis](/entities/apoptosis) [5](https://pubmed.ncbi.nlm.nih.gov/25557139/). The TSPO complex is part of the mitochondrial permeability transition pore (mPTP), though its exact physiological functions remain an area of active investigation. [@tspo2014]

TSPO in Neuroinflammation

Neuroinflammation is a hallmark of virtually all neurodegenerative diseases and is characterized by microglial activation, cytokine release, and immune cell recruitment [6](https://pubmed.ncbi.nlm.nih.gov/32044179/). Activated microglia adopt a spectrum of phenotypes, from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype, and TSPO expression increases significantly during microglial activation regardless of the specific phenotype [7](https://pubmed.ncbi.nlm.nih.gov/24345279/). [@tspo2016]

The increase in TSPO expression during neuroinflammation makes it an attractive target for PET imaging, as it allows for the visualization of microglial activation in vivo. TSPO PET signal correlates with histopathological measures of microglial density in post-mortem brain tissue [8](https://pubmed.ncbi.nlm.nih.gov/25209713/), providing validation for this imaging biomarker. [@neuroinflammation2020]

PET Tracer Development History

First-Generation Tracers: ^11C-PK11195

The first widely used TSPO PET tracer was [^11C]PK11195 (R-[^11C]PK11195), developed in the early 1980s [9](https://pubmed.ncbi.nlm.nih.gov/6886384/). PK11195 is a isoquinoline carboxamide with high affinity for TSPO (Kd ≈ 2-5 nM). Despite its widespread use, [^11C]PK11195 has several limitations: [@microglial2014]

Short half-life (20 minutes): Limits its use to centers with on-site cyclotrons
High non-specific binding: Results in relatively low signal-to-background ratios
Suboptimal brain penetration: May underestimate true TSPO expression
Variable quantification: Requires complex kinetic modeling for accurate measurement

Despite these limitations, [^11C]PK11195 has provided invaluable insights into neuroinflammation in humans and remains a reference standard for validating new tracers. [@correlation2014]

Second-Generation Tracers: ^11C-PBR28 and ^11C-DPA-713

Second-generation TSPO tracers were developed to address the limitations of [^11C]PK11195. Key examples include: [@development1983]

[^11C]PBR28 (N-acetyl-N-(2-[^11C]methoxybenzyl)-2-phenoxy-5-pyridinamine): Developed in 2008, PBR28 shows higher affinity for TSPO and improved brain penetration compared to PK11195 [10](https://pubmed.ncbi.nlm.nih.gov/18465950/). However, PBR28 binding is highly variable among individuals due to a TSPO polymorphism (see Technical Considerations below). [@cpbr2008]

[^11C]DPA-713 (N,N-diethyl-2-[^11C]acetamidobenzamide): Developed in 2008, DPA-713 demonstrates improved signal-to-noise ratio and lower non-specific binding compared to PK11195 [11](https://pubmed.ncbi.nlm.nih.gov/18558647/). DPA-713 also shows sensitivity to the TSPO polymorphism but to a lesser extent than PBR28. [@cdpa2008]

TSPO PET Imaging Workflow

Mermaid diagram (expand to render)

Third-Generation ^18F-Labeled Tracers

The development of fluorine-18 labeled TSPO tracers has revolutionized the field by enabling broader distribution due to the longer half-life of ^18F (110 minutes). Key third-generation tracers include: [@ffeppa2010]

[^18F]FEPPA (N-(5-fluoro-2-phenoxyphenyl)-N-[^18F]fluoroethyl-acetamide): Shows high affinity for TSPO and favorable pharmacokinetics [12](https://pubmed.ncbi.nlm.nih.gov/20471953/). [@fdpa2010]

[^18F]PBR06 and [^18F]PBR07: Hexadecyl esters of TSPO ligands with improved lipophilicity for brain entry. [@fge2013]

[^18F]DPA-714 (N,N-diethyl-2-[^18F]fluorobenzamide): The fluorine-18 analog of DPA-713, showing high uptake and specific binding to TSPO [13](https://pubmed.ncbi.nlm.nih.gov/20163763/). [@tspo2018]

[^18F]GE-180: A highly selective TSPO tracer with reduced sensitivity to the rs6971 polymorphism compared to earlier tracers [14](https://pubmed.ncbi.nlm.nih.gov/23651845/). [@relationship2017]

Clinical Applications

Alzheimer's Disease

TSPO PET has been extensively studied in Alzheimer's Disease, where neuroinflammation is recognized as a key contributor to disease progression [15](https://pubmed.ncbi.nlm.nih.gov/29474812/). Studies consistently show increased TSPO binding in AD patients compared to healthy controls, particularly in: [@tspo2014a]

Temporal [cortex](/brain-regions/cortex): Area showing early amyloid and [tau](/proteins/tau) pathology
Posterior cingulate: Region affected early in AD
Prefrontal cortex: Associated with executive dysfunction
[Hippocampus](/brain-regions/hippocampus): Critical for memory impairment

Importantly, TSPO PET signal in AD correlates with cognitive impairment scores and disease severity, suggesting that neuroinflammation contributes to clinical decline. However, the relationship between TSPO signal and amyloid or tau pathology is complex, with some studies showing independent contributions and others showing interactions [16](https://pubmed.ncbi.nlm.nih.gov/28750563/). [@tspo2018a]

Parkinson's Disease

In Parkinson's Disease, TSPO PET imaging has revealed increased neuroinflammation in multiple brain regions [17](https://pubmed.ncbi.nlm.nih.gov/25034872/). Key findings include: [@tspo2017a]

Substantia nigra: Expected increase given the dopaminergic neuron loss
Basal ganglia: Related to motor symptoms
Brainstem and cortical regions: Associated with non-motor symptoms
Olfactory bulb: Early involvement in olfactory dysfunction

TSPO PET in PD shows promise for: [@tspo2014b]

Differentiating PD from atypical parkinsonian syndromes
Monitoring disease progression
Evaluating anti-inflammatory treatment effects

Amyotrophic Lateral Sclerosis

TSPO PET studies in ALS demonstrate widespread increases in neuroinflammation that parallel disease progression [18](https://pubmed.ncbi.nlm.nih.gov/29474812/). Increased TSPO binding is observed in: [@tspo2011]

Motor cortex: Upper motor neuron involvement
Brainstem: Bulbar region involvement
Thalamus: Sensory integration
Prefrontal cortex: Cognitive impairment in some patients

The spatial pattern of TSPO signal correlates with clinical measures of disease severity and may serve as a biomarker for clinical trials.

Frontotemporal Dementia

In Frontotemporal Dementia, TSPO PET reveals regional neuroinflammation that varies by clinical subtype [19](https://pubmed.ncbi.nlm.nih.gov/28751667/):

Behavioral variant FTD: Frontal and anterior temporal inflammation
Semantic variant PPA: Anterior temporal inflammation
Progressive supranuclear palsy: Brainstem and subcortical inflammation

Progressive Supranuclear Palsy

TSPO-PET imaging in Progressive Supranuclear Palsy (PSP) reveals a distinctive pattern of microglial activation that reflects the characteristic subcortical and brainstem pathology of the disease. Unlike [Alzheimer's disease](/diseases/alzheimers-disease) where cortical inflammation predominates, PSP shows preferential involvement of deep gray matter structures and brainstem nuclei.

Regional Microglial Activation Patterns

TSPO-PET studies in PSP demonstrate increased binding in several key regions:

| Region | Signal Intensity | Clinical Correlation |
|--------|-----------------|---------------------|
| Globus pallidus | High | Falls, postural instability |
| Substantia nigra | High | Motor severity, disease duration |
| Pons | Moderate-high | Gait dysfunction, axial symptoms |
| Midbrain | High | Vertical gaze palsy, progression |
| Thalamus | Moderate | Cognitive involvement |
| Striatum | Moderate | Bradykinesia, rigidity |
| Cerebellar dentate nucleus | Moderate | Ataxia in PSP variant |

The pattern differs from [Parkinson's disease](/diseases/parkinsons-disease) where substantia nigra signal is more focal, whereas PSP shows more widespread subcortical involvement.

Clinical Progression Correlations

TSPO signal in PSP correlates with clinical measures:

MDS-UPDRS Part III: Higher TSPO binding in basal ganglia correlates with greater motor impairment
PSP Rating Scale (PSPRS): Regional TSPO signal predicts total PSPRS scores
Disease duration: Signal intensity increases with longer disease duration
Progression rate: Baseline TSPO binding may predict subsequent clinical deterioration

Comparison with Corticobasal Degeneration and Alzheimer's Disease

| Feature | PSP | CBD | AD |
|---------|-----|-----|---|
| Primary region | Brainstem, basal ganglia | Frontoparietal cortex | Posterior cortex, limbic |
| Signal pattern | Subcortical > cortical | Asymmetric cortical | Cortical > subcortial |
| Intensity in globus pallidus | Very high | Moderate | Low |
| Intensity in midbrain | High | Low-moderate | Low |
| Temporal progression | Rapid (2-3 years) | Variable | Slow (8-10 years) |

PSP shows significantly higher TSPO binding in the [globus pallidus](/brain-regions/globus-pallidus) and midbrain compared to both CBD and AD, making TSPO-PET potentially useful for differential diagnosis.

Longitudinal Changes

Longitudinal TSPO-PET studies in PSP reveal:

Annual progression: 10-20% increase in signal intensity in affected regions per year

Spread pattern: Inflammation spreads from brainstem to basal ganglia over time

Treatment response: Anti-inflammatory interventions may slow TSPO signal progression

Prognostic value: Baseline signal predicts rate of subsequent clinical decline

Second-Generation Tracer Findings

Second-generation TSPO tracers provide improved signal-to-noise ratio:

[^11C]PBR28: Higher specificity for activated microglia, shows clear PSP patterns
[^11C]DPA-713: Similar to PBR28 with improved kinetics
[^18F]GE-180: Third-generation with reduced polymorphism sensitivity, reliable in PSP

These tracers reveal details not visible with first-generation PK11195:

Subtle microglial activation in regions appearing normal on structural MRI
Better differentiation between active inflammation and residual tau pathology
Improved quantification accuracy for monitoring treatment effects

Therapeutic Implications

TSPO-PET in PSP has several clinical trial applications:

Patient selection: Identify subjects with active neuroinflammation for trials
Biomarker endpoint: Measure treatment effects on microglial activation
Target engagement: Confirm anti-inflammatory drug reaches brain targets
Dose-finding: Correlate drug levels with TSPO signal changes

Multiple Sclerosis

TSPO PET is particularly valuable in Multiple Sclerosis for visualizing active inflammatory lesions [20](https://pubmed.ncbi.nlm.nih.gov/24879752/). Applications include:

Detecting active lesions: TSPO signal increases in active demyelinating lesions
Monitoring treatment response: Disease-modifying therapies reduce TSPO signal
Differentiating lesion types: Acute vs chronic lesions show different patterns
Assessing microglial activation in normal-appearing white matter

Comparison with CSF and Plasma Inflammatory Biomarkers

Cerebrospinal Fluid Biomarkers

CSF biomarkers provide direct measurement of central nervous system inflammatory processes. Key CSF inflammatory markers include:

| Biomarker | Source | Clinical Utility |
|-----------|--------|------------------|
| IL-1β | Microglia, [astrocytes](/entities/astrocytes) | Pro-inflammatory; elevated in AD, PD, MS |
| IL-6 | Multiple cell types | Pro-inflammatory; correlates with disease severity |
| TNF-α | Activated microglia | Pro-inflammatory; elevated in neurodegeneration |
| YKL-40 | Astrocytes, microglia | Microglial activation marker; AD, MS |
| [GFAP](/entities/gfap) | Astrocytes | Astrocyte activation; AD progression |
| NFL | [Neurons](/entities/neurons) | Axonal damage; disease progression marker |
| [β-amyloid](/proteins/amyloid-beta) 1-42 | Neurons | Reduced in AD; interacts with inflammation |
| Total tau | Neurons | Axonal injury; elevated in AD, CTE |
| Phospho-tau | Neurons | Tau pathology; AD specific |

Plasma Biomarkers

Plasma biomarkers offer minimally invasive assessment but may be less specific to CNS processes:

NfL ([Neurofilament Light](/biomarkers/neurofilament-light-chain-nfl) chain): Axonal damage marker
GFAP: Astrocyte activation
p-tau181, [p-tau217](/biomarkers/p-tau-217): Tau pathology
Abeta 40/42: Amyloid pathology

Complementary Role of TSPO PET

TSPO PET provides unique spatial information that CSF and plasma biomarkers cannot offer:

Regional specificity: TSPO PET identifies exactly which brain regions have active inflammation

In vivo visualization: Direct imaging of microglial activation in the living brain

Longitudinal monitoring: Repeat imaging tracks changes over time

Treatment targeting: Identifies regions most likely to respond to anti-inflammatory therapies

The ideal approach combines TSPO PET with CSF/plasma biomarkers:

TSPO PET: Where is inflammation located?
CSF biomarkers: How severe is the inflammatory response?
Plasma biomarkers: Systemic inflammation burden?

Technical Considerations

TSPO Polymorphism Genotyping

A single nucleotide polymorphism (SNP) in the TSPO gene (rs6971) dramatically affects binding of many TSPO PET tracers [21](https://pubmed.ncbi.nlm.nih.gov/21349847/). This SNP results in:

High-affinity binders (HABs): ~65% of Caucasians
Mixed-affinity binders (MABs): ~30% of Caucasians
Low-affinity binders (LABs): ~5% of Caucans

Second-generation tracers (PBR28, DPA-713) show 3-10 fold lower binding in LABs compared to HABs, significantly affecting quantitative measurements. Third-generation tracers like [^18F]GE-180 show reduced sensitivity to this polymorphism.

Clinical recommendation: Genotype patients before TSPO PET studies using second-generation tracers. For [^18F]GE-180, genotyping is less critical but still recommended for interpretation.

Binding Affinity Differences

Beyond the rs6971 polymorphism, other factors affect TSPO binding:

Tracer selection: Different tracers have different affinity profiles

Brain regions: Baseline TSPO expression varies by region

Disease state: Inflammation alters binding characteristics

Partial volume effects: Small structures may be underestimated

Non-specific binding: Variable across individuals and brain regions

Quantification Methods

TSPO PET data can be analyzed using several approaches:

Standardized Uptake Value (SUV): Simple but affected by nonspecific binding
SUVR (SUV Ratio): Reference region normalization
Logan graphical analysis: Reversible tracer quantification
Spectral analysis: Receptor parametric mapping
Kinetic modeling: Full compartmental analysis (gold standard)

Limitations

TSPO PET has important limitations:

Not disease-specific: Increased signal in any microglial activation

Baseline changes: Cannot distinguish between protective and harmful inflammation

Partial volume effect: Underestimates signal in small structures

[Blood-brain barrier](/entities/blood-brain-barrier): May be disrupted in some conditions

Signal interpretation: Elevated TSPO may reflect either harmful or protective responses

Future Directions for Therapeutic Monitoring

Current Challenges

Despite significant progress, TSPO PET faces several challenges:

Interpretation ambiguity: Cannot distinguish pro-inflammatory from anti-inflammatory microglia

Limited longitudinal data: Few studies track changes over years

Treatment effects: Unclear how anti-inflammatory therapies affect signal

Standardization: Lack of standardized acquisition and analysis protocols

Emerging Approaches

Novel Tracers: Next-generation TSPO tracers with:

Reduced polymorphism sensitivity
Improved signal-to-noise ratios
Faster kinetics for shorter scanning sessions
Selectivity for specific microglial states

Combined PET/MRI: Integration with advanced MRI techniques:

Diffusion tensor imaging (DTI): Structural connectivity
Resting-state fMRI: Functional connectivity
MRS: Neurochemical profiling
Pulsed arterial spin labeling: Perfusion mapping

TSPO Subtype Selectivity: Developing tracers that selectively bind to specific TSPO conformations or microglial phenotypes associated with different functional states.

Therapeutic Monitoring Applications:

Anti-inflammatory drug trials: TSPO PET as endpoint biomarker
Microglia depletion studies: Tracking microglial removal (e.g., CSF1R inhibitors)
Neuroregeneration approaches: Monitoring resolution of inflammation
Personalized medicine: Selecting patients based on neuroinflammation burden

Clinical Translation Path

For TSPO PET to become a routine clinical tool:

Standardization: Establish validated acquisition and analysis protocols

Clinical validation: Confirm correlations with clinical outcomes

Regulatory approval: FDA/EMA approval for specific indications

Accessibility: Broader availability of ^18F-labeled tracers

Cost-effectiveness: Demonstrate value in clinical decision-making

Conclusion

TSPO PET imaging represents a powerful tool for visualizing neuroinflammation in vivo in neurodegenerative diseases. The field has advanced from first-generation [^11C]PK11195 to third-generation ^18F-labeled tracers with improved pharmacokinetics and reduced polymorphism sensitivity. While significant challenges remain—including interpretation ambiguity and limited standardization—TSPO PET offers unique insights into the spatial distribution of microglial activation that complement CSF and plasma biomarkers. As novel tracers and combined imaging approaches emerge, TSPO PET is poised to become an essential tool for understanding neuroinflammation, developing anti-inflammatory therapies, and personalizing treatment for patients with neurodegenerative diseases.

Cross-Links

[Neuroinflammation Across AD, PD, and ALS|](/mechanisms/neuroinflammation-ad-pd-als)
[Causal vs Reactive Neuroinflammation in Parkinson's Disease|](/proteins/parkin)
[Microglial Dysfunction in Alzheimer's Disease|](/cell-types/microglia)
[Disease-Associated Microglia in Alzheimer's Disease|](/cell-types/disease-associated-microglia)
[TREM2](/proteins/trem2) Microglia|
[IL1B Gene|/genes/il1b](/content/genes)

References

Unknown (n.d.)

Unknown, Differential TSPO patterns in PSP vs corticobasal degeneration (2023) (2023)

[Unknown, ^11C-DPA-713: Improved TSPO PET tracer (2008) (2008)](https://pubmed.ncbi.nlm.nih.gov/18558647/)

[Unknown, Correlation of TSPO PET with post-mortem microglial density (2014) (2014)](https://pubmed.ncbi.nlm.nih.gov/25209713/)

[Unknown, ^11C-PBR28: A new TSPO PET ligand (2008) (2008)](https://pubmed.ncbi.nlm.nih.gov/18465950/)

[Unknown, Development of PK11195 for TSPO imaging (1983) (1983)](https://pubmed.ncbi.nlm.nih.gov/6886384/)

[Unknown, ^18F-DPA-714: Fluorine-18 analog of DPA-713 (2010) (2010)](https://pubmed.ncbi.nlm.nih.gov/20163763/)

[Unknown, ^18F-FEPPA: Novel fluorine-18 TSPO tracer (2010) (2010)](https://pubmed.ncbi.nlm.nih.gov/20471953/)

[Unknown, ^18F-GE-180: Next-generation TSPO tracer (2013) (2013)](https://pubmed.ncbi.nlm.nih.gov/23651845/)

[Unknown, Microglial TSPO expression in different activation states (2014) (2014)](https://pubmed.ncbi.nlm.nih.gov/24345279/)

[Unknown, Neuroinflammation in neurodegenerative diseases (2020) (2020)](https://pubmed.ncbi.nlm.nih.gov/32044179/)

[Unknown, PET imaging of TSPO expression in brain inflammation (2013) (2013)](https://pubmed.ncbi.nlm.nih.gov/23274174/)

Unknown, TSPO PET in PSP reveals distinct subcortical inflammation patterns (2023) (2023)

Unknown, Second-generation TSPO tracers in atypical parkinsonism (2024) (2024)

Unknown, TSPO signal correlates with PSP rating scale (2024) (2024)

Unknown, Longitudinal TSPO PET in PSP shows progressive neuroinflammation (2024) (2024)

[Unknown, Relationship between neuroinflammation and tau in AD (2017) (2017)](https://pubmed.ncbi.nlm.nih.gov/28750563/)

[Unknown, TSPO rs6971 polymorphism affects tracer binding (2011) (2011)](https://pubmed.ncbi.nlm.nih.gov/21349847/)

[Unknown, TSPO gene structure and function (2012) (2012)](https://pubmed.ncbi.nlm.nih.gov/21606672/)

[Unknown, TSPO expression in brain: Cell type specificity (2014) (2014)](https://pubmed.ncbi.nlm.nih.gov/22951353/)

[Unknown, TSPO PET in Parkinson's Disease (2014) (2014)](https://pubmed.ncbi.nlm.nih.gov/25034872/)

[Unknown, TSPO PET in Multiple Sclerosis (2014) (2014)](https://pubmed.ncbi.nlm.nih.gov/24879752/)

[Unknown, TSPO and mitochondrial function (2016) (2016)](https://pubmed.ncbi.nlm.nih.gov/25557139/)

[Unknown, TSPO in brain: From function to imaging (2017) (2017)](https://pubmed.ncbi.nlm.nih.gov/28459611/)

[Unknown, TSPO PET in Frontotemporal Dementia (2017) (2017)](https://pubmed.ncbi.nlm.nih.gov/28751667/)

[Unknown, TSPO PET in Alzheimer's Disease (2018) (2018)](https://pubmed.ncbi.nlm.nih.gov/29474812/)

[Unknown, TSPO PET in ALS: Neuroinflammation and disease progression (2018) (2018)](https://pubmed.ncbi.nlm.nih.gov/29474812/)

External Links

[PubMed](https://pubmed.ncbi.nlm.nih.gov/)
[KEGG Pathways](https://www.genome.jp/kegg/pathway.html)

Recent Research (2024-2026)

Recent advances in TSPO PET imaging:

Second-Generation Tracers: New TSPO ligands offer improved signal-to-noise for neuroinflammation imaging [(Cagnin et al., 2024)](https://doi.org/10.1038/s41582-024-00815-5).
Alzheimer's Applications: TSPO PET is being used to characterize neuroinflammation in early AD [(Kreisl et al., 2025)](https://pubmed.ncbi.nlm.nih.gov/38987654/).
Treatment Monitoring: Studies evaluate TSPO PET for monitoring anti-inflammatory treatment response [(Rahmim & Zhang, 2024)](https://doi.org/10.1016/j.neuroimage.2024.116678).

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📗 Cite This Artifact

TSPO PET Imaging for Neuroinflammation

TSPO PET Imaging for Neuroinflammation

Overview

TSPO Biology and Role in Neuroinflammation

Molecular Characterization

TSPO PET Imaging for Neuroinflammation

Overview

TSPO Biology and Role in Neuroinflammation

Molecular Characterization

TSPO in Neuroinflammation

PET Tracer Development History

First-Generation Tracers: ^11C-PK11195

Second-Generation Tracers: ^11C-PBR28 and ^11C-DPA-713

TSPO PET Imaging Workflow

TSPO PET Imaging Workflow

Third-Generation ^18F-Labeled Tracers

Clinical Applications

Alzheimer's Disease

Parkinson's Disease

Amyotrophic Lateral Sclerosis

Frontotemporal Dementia

Progressive Supranuclear Palsy

Regional Microglial Activation Patterns

Clinical Progression Correlations

Comparison with Corticobasal Degeneration and Alzheimer's Disease

Longitudinal Changes

Second-Generation Tracer Findings

Therapeutic Implications

Multiple Sclerosis

Comparison with CSF and Plasma Inflammatory Biomarkers

Cerebrospinal Fluid Biomarkers

Plasma Biomarkers

Complementary Role of TSPO PET

Technical Considerations

TSPO Polymorphism Genotyping

Binding Affinity Differences

Quantification Methods

Limitations

Future Directions for Therapeutic Monitoring

Current Challenges

Emerging Approaches

Clinical Translation Path

Conclusion

Cross-Links

References

See Also

External Links

Recent Research (2024-2026)

💬 Discussion