Abstract TP51: Cerebral Blood Flow Threshold for Infarction After 3 Hours of Ischemia Determined in a Porcine Model of Stroke
Bibliographic record
Abstract
Introduction: CT Perfusion (CTP) derived ischemia-time dependent thresholds may help with treatment decision making by allowing infarct delineation at admission and prediction of infarct growth over time. The accepted 3h ischemia-time cerebral blood flow (CBF) infarction threshold had been determined by Jones et al in primates using hydrogen clearance. The same threshold from CTP has not been determined. We used a porcine acute stroke model to find this threshold with contemporaneous CTP and PET imaging. Hypothesis: CTP derived 3h ischemia-time infarction CBF threshold will be near 12 mL100g -1 min -1 as determined in primates. Methods: Cerebral ischemia was induced in the left hemisphere of 11 pigs by injecting endothelin-1 (ET-1) into the cortex. CTP scans were acquired subsequently at 10 min and then 30 min intervals throughout the experiment. At 2.5h, 18F-FFMZ was injected, PET acquisition started at 3h. A median CBF map was produced after co-registering maps from each CTP study. Median CBF maps, PET images, average images from the baseline CTP study, and blood volume (BV) maps from the 10min post ET-1 CTP study were co-registered. ROIs were drawn over the cortex on the affected and contralateral side and superimposed onto all images. Infarct was identified on PET images with a threshold derived from the contralateral ROI. Average images were used to remove white matter from the affected side ROI. Blood vessels were excluded on BV maps with a threshold derived from the affected side ROI. Remaining infarct and non-infarct ROIs were superimposed onto the median CBF map and pixel values were imported into Matlab for ROC analysis. Results: Of 11 animals, 6 developed infarction. The optimal CBF infarction thresholds determined from the ROC curves were 10.1, 8.9, 15.0, 13.2, 12.1, and 16.2mL100g -1 min -1 . The average threshold was 12.6 ± 2.8 mL100g -1 min -1 . Conclusions: CTP derived CBF threshold for infarction at 3-h ischemia time agrees well with the accepted literature value. Infarction thresholds at other ischemia times can be found using this model by varying the time between ET-1 injection and PET 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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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 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".