Abstract WMP23: Enhanced Collaterals in Patients with Large Vessel Stroke from Intracranial Atherosclerosis: An Automated CT Perfusion-based Study
Bibliographic record
Abstract
Background and Purpose: Patients with intracranial atherosclerotic disease (ICAD) are believed to have enhanced collateral flow. We have anecdotally perceived that large vessel occlusion acute strokes (LVOS) patients due to ICAD have more benign automated CT perfusion (CTP) defect profiles, potentially reflecting improved collateralization in comparison to embolic LVOS. Methods: Retrospective review of a prospectively collected interventional stroke database from Sep 2010-Mar 2015. Patients were dichotomized into ICAD vs. other etiology. Patients with a technically adequate CTP and an intracranial ICA, MCA M1 or M2 occlusion were included. Tandem extracranial carotid occlusions were excluded due to the known effects on bolus dispersion and delay of bolus passage. Ischemic core (relative CBF<30%) and perfusion defects were estimated by RAPID automated CTP. The primary endpoint was to compare the ratio of CTP Tmax>4s (“benign oligemia”) / Tmax>6s (“territory at risk”) between the two groups. Results: A total of 250 patients fit inclusion criteria, of whom 21 (8%) were classified as ICAD and 229 had other stroke etiologie. Baseline characteristics were similar between the two groups, except for higher hemoglobin A1c levels (p<0.01), higher baseline systolic blood pressure (p<0.01); and lower rates of atrial fibrillation (p<0.01) in the ICAD group. There were no differences in ischemic core (p=0.51), perfusion defect Tmax>4s (p=0.86), Tmax>6s (p=0.57) and Tmax>10s (p=0.17). ICAD patients had a median ratio of Tmax>4s/ Tmax>6s of 2. A Tmax>4s/ Tmax>6s ratio≥2 showed a specificity of 83% and a sensitivity of 52%, and was more common in the ICAD group (p=0.1). Multivariate logistic regression analysis revealed that higher rates of Tmax>4s/ Tmax>6s ratio≥2 (OR 3.36 95% CI 1.05-10.71, p=0.04), lower rates of atrial fibrillation(OR 0.17 95% CI 0.04-0.86, p=0.03), and higher systolic pressure (OR 1.03 95% CI 1.01-1.05, p=0.002) were independently associated with ICAD. Conclusion: A RAPID CTP Tmax>4s/ Tmax>6s ratio≥2 profile is an independent and highly specific indicator of underlying ICAD LVOS etiology.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".