Association between medial temporal and neocortical Tau SUVR across tau imaging agents: HEAD Study
Bibliographic record
Abstract
Abstract Background The association between medial temporal and neocortical SUVR depends on availability of cortical tau. However, tracer differences in affinity and off‐target binding might interfere in these associations. Here, we examined the association between medial temporal and neocortical SUVR using voxel‐based approach. Method We included 92 individuals (46 Cognitively Unimpaired and 46 Cognitively Impaired) from the HEAD Study recruited at McGill University. All individuals were assessed for amyloid‐β (Aβ) deposition using [18F]AZD4694‐PET and at least two tau‐PET ligands ([18F]MK6240 and [18F]Flortaucipir). A subset of 25 individuals had 2 additional tau‐PETs scans: [18F]RO948 and [18F]PI‐2620. Voxel‐based regression models evaluated the relationship between PET tracers’ uptake in the entorhinal cortex (EC) and its association with the tracer’s uptake in later Braak regions. All models include Aβ‐PET, age, and sex as covariates and RFT was used to account for multiple comparisons. Additionally, we extracted the number of significant voxels in the associations within each Braak regions. Result Positive associations were observed between tau‐PET SUVR in the EC (Figure 1). [18F]MK6240 EC was correlated with tracer uptake in the whole cortex. [18F] Flortaucipir was associated with tracer uptake in similar regions, albeit showing a lower t‐value. [18F]PI2620 EC uptake correlated with binding in regions Braak II‐V. Finally, [18F]RO948 was associated with uptake in regions Braak II‐IV. We further validated our results by extracting the number of significant voxels in each Braak regions. [18F]MK6240 showed the highest percentage of spatial extent of tau spreading in all Braak regions, followed by [18F]Flortaucipir and [18F]RO948. [18F]PI2620 demonstrated the lowest spatial extent. Conclusion [18F]MK6240 SUVR better predicted the spatial extent of tau spreading in the whole cortex. Results were concordant at the voxel and region‐on‐interested levels. [18F]Flortaucipir showed similar results, in lower magnitude. Finally, [18F]PI2620 and [18F]RO948 were further lower. Nevertheless, the later analyses were conducted in a smaller sample. Our results support the concept that MK6240 affinity possibly explain these results.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".