Imaging cardiac sarcoidosis with FLT-PET with comparison to FDG-PET: a prospective pilot study
Bibliographic record
Abstract
670 Purpose: FDG-PET is frequently used for the diagnosis and evaluation of therapy response in cardiac sarcoidosis (CS). The normal biodistribution of FDG requires special dietary preparation in order to suppress myocardial physiological uptake. Unfortunately, a significant proportion of patients will present physiological myocardial uptake despite optimal preparation, limiting the diagnostic value of FDG in these patients. Some non-FDG tracers, such as FLT, have shown uptake in sarcoidosis lesions but do not demonstrate uptake within normal myocardium. This prospective study was designed to compare FLT-PET and FDG-PET for the evaluation of cardiac sarcoidosis (CS). Methods: 14 subjects with extra-cardiac sarcoidosis (ECS) (11 with CS) were prospectively recruited and imaged with FDG-PET, FLT-PET and rest perfusion PET. Subjects undergoing FDG-PET imaging were prepared with a low-carbohydrate, high fat and protein-permitted diet followed by fasting, as well as IV heparin, while no special preparation was performed for FLT-PET. Two blinded, experienced readers independently reviewed all studies. Heart Rhythm Society criteria served as gold standard for the diagnosis of CS. Results: The combination of perfusion/FLT-PET and perfusion/FDG-PET performed comparably in this cohort, both having an accuracy for CS of 96% (95% CI: 0.7 - 1.0), with a sensitivity of 91% (95% CI: 0.59 - 1.0) and specificity of 100% (95% CI: 1.0 - 1.0). 7 subjects showed myocardial FDG uptake consistent with active CS, with 6 of these subjects also demonstrating increased FLT uptake. One subject with isolated lateral wall uptake on FDG, a normal variant, showed no corresponding uptake on FLT. Inter-observer agreement between FLT and FDG interpretation was very good for both CS (κ = 0.85 (95% CI: 0.57 - 1.0) vs κ = 0.72 (95% CI: 0.38 - 1.0) and ECS (κ = 0.81 (95% CI: 0.46 - 1.0) vs κ = 1.0 (95% CI: 1.0 - 1.0) The sum rest score was strongly correlated with SUVtotal for FLT (r = 0.90, 95% CI: 0.33-0.99, p = 0.014) but not for FDG (p = 0.75). Conclusions: FLT PET has excellent accuracy for CS and requires no special patient preparation. The distribution of FDG differed from that of FDG, suggesting that the tracers provide different pathophysiological information and that myocardial FLT uptake may serve as a distinct biomarker for CS.
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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 | 0.004 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".