Related Experiment Video
Updated: Oct 2, 2025
Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia
Published on: September 20, 2015
Reduced Acquisition Time [18F]GE-180 PET Scanning Protocol Replaces Gold-Standard Dynamic Acquisition in a Mouse
Artem Zatcepin1,2, Steffanie Heindl3, Ulrike Schillinger3
1Department of Nuclear Medicine, University Hospital of Ludwig-Maximilians-Universität (LMU) Munich, Munich, Germany.
Aim:
Understanding neuroinflammation after acute ischemic stroke is a crucial step on the way to an individualized post-stroke treatment. Microglia activation, an essential part of neuroinflammation, can be assessed using [18F]GE-180 18 kDa translocator protein positron emission tomography (TSPO-PET). However, the commonly used 60-90 min post-injection (p.i.) time window was not yet proven to be suitable for post-stroke neuroinflammation assessment. In this study, we compare semi-quantitative estimates derived from late time frames to quantitative estimates calculated using a full 0-90 min dynamic scan in a mouse photothrombotic stroke (PT) model.
Materials And Methods:
Six mice after PT and six sham mice were included in the study. For a half of the mice, we acquired four serial 0-90 min scans per mouse (analysis cohort) and calculated standardized uptake value ratios (SUVRs; cerebellar reference) for the PT volume of interest (VOI) in five late 10 min time frames as well as distribution volume ratios (DVRs) for the same VOI. We compared late static 10 min SUVRs and the 60-90 min time frame of the analysis cohort to the corresponding DVRs by linear fitting. The other half of the animals received a static 60-90 min scan and was used as a validation cohort. We extrapolated DVRs by using the static 60-90 min p.i. time window, which were compared to the DVRs of the analysis cohort.
Results:
We found high linear correlations between SUVRs and DVRs in the analysis cohort for all studied 10 min time frames, while the fits of the 60-70, 70-80, and 80-90 min p.i. time frames were the ones closest to the line of identity. For the 60-90 min time window, we observed an excellent linear correlation between SUVR and DVR regardless of the phenotype (PT vs. sham). The extrapolated DVRs of the validation cohort were not significantly different from the DVRs of the analysis group.
Conclusion:
Simplified quantification by a reference tissue ratio of the late 60-90 min p.i. [18F]GE-180 PET image can replace full quantification of a dynamic scan for assessment of microglial activation in the mouse PT model.
Insights
Simplified [18F]GE-180 PET imaging using a late 60-90 min window accurately assesses neuroinflammation in a mouse stroke model. This method, measuring microglia activation via TSPO-PET, offers a viable alternative to full dynamic scans for post-stroke treatment research.
Area of Science:
- Neuroscience
- Radiochemistry
- Medical Imaging
Background:
- Neuroinflammation is critical for individualized post-stroke treatment.
- Microglia activation, a key neuroinflammatory marker, can be assessed using [18F]GE-180 TSPO-PET.
- The optimal time window for TSPO-PET in stroke models requires validation.
Purpose of the Study:
- To compare semi-quantitative estimates from late [18F]GE-180 TSPO-PET scans with quantitative dynamic scans.
- To validate the 60-90 min post-injection (p.i.) time window for assessing neuroinflammation in a mouse stroke model.
Main Methods:
- Used a photothrombotic stroke (PT) mouse model with analysis and validation cohorts.
- Acquired dynamic 0-90 min [18F]GE-180 PET scans and static 60-90 min scans.
- Calculated standardized uptake value ratios (SUVRs) and distribution volume ratios (DVRs) for comparison.
Main Results:
- High linear correlations were found between SUVRs and DVRs across multiple late time frames.
- The 60-90 min p.i. time window showed an excellent linear correlation between SUVR and DVR.
- Extrapolated DVRs from static scans matched dynamic scan results, validating the simplified approach.
Conclusions:
- A simplified quantification method using the late 60-90 min p.i. [18F]GE-180 PET scan is effective.
- This approach can replace full dynamic scans for assessing microglial activation in mouse stroke models.
- This simplification may facilitate individualized post-stroke treatment strategies.
