Nonenhanced Computed Tomography Evaluation Of Ischemic Stroke Patients Presenting After 4.5 Hours From Onset Of Symptoms Using Aspects, Posterior Circulation-Aspects And X-Ray Attenuation Ratio: The “Tissue Window”
Bibliographic record
Abstract
Background: Stroke is a major cause of disability and mortality world-wide. Ischemic stroke is reversible when patients present early. With the current treatment guideline in Nigeria, most ischemic stroke patients present after the 4.5 hours treatment “time window” and are ineligible for intravenous thrombolysis (IVT). However, studies with computed tomography and magnetic resonance imaging have shown variability in the duration of tissue viability, with some remaining viable up to 24 hours and beyond. These advanced imaging are not readily available in the sub-Saharan Africa but the X-ray attenuation ratio of hypoattenuating lesions on the easily accessible nonenhanced computed tomography (NECT), have recently shown to be a valuable alternative. In late presentation, IVT and endovascular thrombectomy (EVT) have proven to have reasonable degree of success in recanalization. Hence, the need for the study. Materials and method: This was a retrospective cross-sectional study of ischemic stroke patients who presented between 4.5 and 24 hours for NECT. The extent of the ischemia was determined using the Alberta stroke programme early CT score (ASPECTS), while the Hounsfield unit ratio of the hypodense lesions was used to determine tissue viability. Results: Fifty-five patients met the inclusion criteria and had a mean age of 58.8 years. Four (7.27%) patients clearly had ASPECTS and Hounsfield unit ratio (HUr) scores suggestive of salvageable penumbral tissue, while another four (7.27%) had the probability of being reversible. Conclusion: Some patients were still eligible for treatment after the current guideline’s 4.5 hours treatment “time window” using the ASPECTS and HUr scores on NECT.
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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 | 0.000 | 0.001 |
| 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 | 0.000 | 0.000 |
| 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".