Abstract 2972: Perfusion CT in Patients with Basilar Artery Occlusion: Diagnostic and Prognostic Value in the Basilar Artery International Cooperation Study
Bibliographic record
Abstract
Background: The posterior circulation Acute Stroke Prognosis Early CT Score (pc-ASPECTS) applied to CT angiography source images (CTA-SI) predicts the functional outcome of patients with basilar artery occlusion (BAO). Compared with CTA-SI, perfusion CT (CTP) may provide added information. We assessed the diagnostic and prognostic impact of CTP compared with CTA-SI among patients in the Basilar Artery International Cooperation Study (BASICS) Methods: BASICS was a prospective observational registry of consecutive patients with acute symptomatic BAO. We applied pc-ASPECTS to CTA-SI and cerebral blood volume (CBV), cerebral blood flow (CBF), time-to-peak (TTP) and mean-transit-time (MTT) parameter maps in a 3-reader-consensus with readers blinded to clinical data. Hypoattenuation on CTA-SI, a relative reduction in CBV or CBF, or relative increase in MTT or TTP was rated as abnormal. Clinical outcome was measured with the modified Rankin Scale (mRS) score at 1 month. Results: Among 592 patients in the BASICS registry, 27 patients (4.6%) had CTP studies performed. Median (interquartile-range) pc-ASPECTS values on TTP/MTT, CTA-SI, CBF and CBV were 6 (5-8), 7 (5-9), 8 (6-9) and 10 (8.75-10), respectively (p<0.001). The proportion of patients with any perfusion abnormalities in the posterior circulation was highest for TTP/MTT (93%; CI 95% 74% to 99%), compared with 78% (CI 95% 57% to 91%) for both CTA-SI and CBF and 46% (CI 95% 27% to 66%) for CBV (p<0.001). At 1 month, 9 patients (33%) had a favourable outcome (mRS scores 0-3), 8 patients (30%) had an unfavourable outcome (mRS scores 4-5) and 10 patients (37%) were deceased. In univariate analysis, pc-ASPECTS scores did not correlate with outcome mRS scores for all imaging modalities (Spearman’s Rho, p>0.1 for all). All three patients (100%) with a CBV pc-ASPECTS <8 compared to 6 of 23 patients (26%) with a CBV pc-ASPECTS >8 died (p=0.03). Conclusion: CTP was performed in a minority of patients in the BASICS registry population. Perfusion disturbances in the posterior circulation were most frequent and most pronounced on TTP and MTT parameter maps. Extensive reduction of CBV, defined as a pc-ASPECTS <8, may indicate patients with a high case fatality.
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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 | 0.002 | 0.004 |
| 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 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".