Abstract WP49: Defining the Acute Infarct Core with CT Perfusion in Ischemic Stroke: Physiological and Technical Issues
Bibliographic record
Abstract
Background: CT Perfusion (CTP) defined hemodynamic parameters used to delineate admission infarct core can be affected by truncated data acquisition, recanalization status and reactive hyperemia. We determined the optimal CTP parameter for infarct demarcation while taking these variables into account. Methods: 30 patients had CTP/NCCT scanning within 6 hours of ictus, a 24 hour CTA and an NCCT at 3 months post stroke to define final infarct. Patients were analyzed according to: 1) the percent wash out (truncation) of the ischemic time density curve (ITDC) and 2) recanalization status defined using the 24 hour CTA. CTP functional maps were generated using delay insensitive CTP software (GE Healthcare). For all patients, the total ischemic lesion (infarct+penumbra+benign oligemia) was defined using the contrast delay plus mean transit time map. Cerebral blood flow (CBF), cerebral blood volume (CBV) and the product of CBF and CBV (CBFxCBV) were used to define the infarct core defect, according to established thresholds, and compared with the infarct volume defined on the 3 month NCCT. The coefficients of correlation (R2) of linear regression models were used for the comparisons. Results: R2 values for admission CBF, CBV, and CBFxCBV defect versus final infarct volume for patients with and without truncation of the ITDC were 0.89, 0.49, 0.65 and 0.90, 0.42, 0.68, respectively; while R2 values for patients with and without recanalization at 24 hours were 0.73, 0.33, 0.44 and 0.84, 0.54, 0.45, respectively. In addition, for the recanalization group with and without truncation of the ITDC, R2 for CBF, CBV, CBFxCBV versus final infarct volume were 0.73, 0.12, 0.31 and 0.79, 0.58, 0.56, respectively. Hyperemia, defined as an increase in CBV relative to the contralateral hemisphere, was observed in 30% of patients. Both hyperemia and ITDC truncation led to poor correlation between the CBV defect and NCCT defined infarct volume. Conclusion: CBF is the optimal parameter for determining the size of the acute infarct core as it is not affected by truncation of the ITDC and autoregulatory vasodilation causing reactive hyperemia.
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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 | 0.003 | 0.007 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".