[68Ga]Ga-FAPI versus 2-[18F]FDG PET/CT in patients with autoimmune thyroiditis: a case control study
Bibliographic record
Abstract
Abstract Purpose Radiolabelled fibroblast activation protein inhibitors (FAPIs) are becoming increasingly important for imaging various tumour diseases. However, it is essential to be aware of potential pitfalls. Here, we investigate FAP expression in the thyroid gland in autoimmune thyroiditis (AIT). Methods AIT patients with pathological thyroid uptake on [ 68 Ga]Ga-FAPI PET were compared with glucose metabolism on 2-[ 18 F]FDG PET in terms of SUV max /SUV peak /SUV mean /tissue-to-background ratio (TBR), and with a healthy control group. Results Between September 2019 and July 2021, 6 patients presented with a visually increased thyroid uptake and TBR on [ 68 Ga]Ga-FAPI PET. In the retrospective clinical work-up, all patients had known or newly diagnosed AIT. Compared to a matched healthy control group, FAP expression and glucose metabolism were significantly increased ([ 68 Ga]Ga-FAPI (SUV peak ): 7.0 vs. 1.7; p = 0.004/(TBR bloodpool ): 6.8 vs. 1.7; p = 0.002; 2-[ 18 F]FDG (SUV peak ): 3.9 vs. 1.4; p = 0.004/(TBR bloodpool ): 4.0 vs. 1.2; p = 0.041). However, there was no significant difference in median uptake between [ 68 Ga]Ga-FAPI and 2-[18F]FDG PET (SUV peak : 7.3 vs. 5.6; p = 0.104). Conclusion Patients with AIT show higher thyroid uptake on [ 68 Ga]Ga-FAPI and 2-[ 18 F]FDG PET. Incidental thyroid uptake is another pitfall in the interpretation of [ 68 Ga]Ga-FAPI PET and should prompt a clinical work-up.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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 teacher head, 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".