121118F-Fluoride PET-CT in the detection of early bioprosthetic valve degeneration
Bibliographic record
Abstract
Background: Bioprosthetic valve degeneration is increasingly common, often unheralded and can be catastrophic. Methods: Degenerate bioprosthetic valves were assessed by micro-positron emission tomography (PET), high resolution micro-computed tomography (CT) and histopathology. Patients were recruited to a clinical study either with end-stage bioprosthetic valve dysfunction (Cohort 1) or without known valve dysfunction (Cohort 2) and underwent contrast-enhanced CT angiography, 18F-fluoride PET and serial echocardiography. Results: Fifteen degenerate explanted bioprosthetic valves were assessed by micro-PET/CT and all of these valves exhibited significant uptake of 18F-fluoride. Histological analysis demonstrated leaflet calcification in 13 of the 15 valves whilst other important histological features included leaflet thrombosis, fibrosis and severe disruption of collagen architecture. 18F-Fluoride localised to these histological features even in the absence of calcification. In Cohort 1, all patients with bioprosthetic failure (n=6) exhibited leaflet abnormalities on both CT and PET. In Cohort 2 (1 month (n=9), 2 (n=22), 5 (n=20) and >10 years (n=20) post-valve implantation), 3 subjects had bioprosthetic dysfunction on echocardiography, 13 had valve abnormalities on CT (6 spotty calcification, 4 non-calcific leaflet thickening, 7 pannus) and 27 had increased 18F-fluoride PET uptake (target-to-background ratio [TBRmean] 1.55 [1.47–1.92]). Patients with increased 18F-fluoride uptake demonstrated a >10-fold increase in mean gradient over 12 months compared to those without increased uptake (2.3 [0.0–4.0] versus -0.3 [-2.0–1.5] mmHg/year, p<0.001) and good correlations were observed between baseline 18F-fluoride TBRmean values and all echocardiographic measures of subsequent valve dysfunction (e.g. change in peak velocity, r=0.64; p<0.001). On multivariable analysis, baseline 18F-fluoride uptake was the only independent predictor of deterioration in bioprosthetic function, and all patients with TBRmean values ≥2.5 had evidence of overt bioprosthetic failure within 1 year of imaging.
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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 | 0.001 | 0.002 |
| 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 | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".