O05/57 Validation of a novel multiphase CTA perfusion tool compared to CTP in patients with suspected acute ischemic stroke
Bibliographic record
Abstract
Introduction A recently developed multiphase-computed-tomography-angiography(mCTA) tool generates perfusion maps, similar to CT-perfusion(CTP) (i.e., mCTA-perfusion[mCTAp]). Aim of Study To validate the clinical utility of mCTAp. Methods In this multi-reader-multi-case analysis, we included baseline images: mCTAp(StrokeSENS-algorithm) and CTP(4D; GE-Healthcare) from 121 randomly selected patients whose scans were not part of algorithm-development. After excluding 2/121 scans due to poor image-quality, three experienced radiologists read Tmax-and rCBF-maps generated by the test(mCTAp) and reference(CTP) modality. The two reading sessions were separated by 5-days with randomized reading order. Core-laboratory imaging assessments-that used NCCT, mCTA and CTP-were considered as ground-truth. We used ‘reader’ as a random-effect to calculate the diagnostic performance for both modalities(mCTAp/CTP) regarding ischemia detection and side/location. Interpretation-time and inter-rater variability were compared across the modalities. Results AUCs(95%CI) for detecting ischemia using mCTAp and CTP were 0.85(95%CI0.8–0.9) and 0.84(0.8–0.9) respectively(p=0.43). AUCs for the affected side were 0.94(0.92–0.97) and 0.96(0.94–0.98) (p=0.69) respectively; for detecting LVO were 0.84(0.8–0.9) and 0.86(0.8–0.9), (p=0.31) respectively; M2-or-distal occlusion were 0.79(0.73–0.84) and 0.88(0.83–0.92) (p=0.22) respectively, for ACA-occlusion 0.82(0.66–0.98) and 0.93(0.82–1.00) (p=0.15) respectively and for PCA-occlusions 0.9(0.8–1) and 0.99(0.98–0.99) (p=0.01) respectively. The median(IQR) time for image interpretation was 62s(IQR 46–78) and 59s(IQR 42–69) for mCTAp and CTP respectively (p=0.15). Fleiss` Kappa-values for inter-rater reliability in detecting ischemia were 0.5 and 0.8 for mCTAp and CTP respectively. Conclusion mCTAp shows similar performance compared to CTP in assisting readers to detect ischemia and its side/location, requiring less radiation exposure, acquisition time and contrast-dose compared to additional-CTP, but mainly as it relates to proximal vessel occlusions. Disclosure of Interest Dr. Menon holds patents on systems of triage in acute stroke, for LVO detection and for mCTAp, and stock ownership in Circle Cardiovascular Inc. Dr. Bala has nothing to declare. Dr. Duszynski is an employee of, and holds stock options for Circle Cardiovascular Imaging Inc. Dr. Nayem Pinky, Dr. Golan and Luis A Souto Maior Neto are employees of Circle Cardiovascular Imaging Inc. All other co-authors have nothing to disclose.
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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 | 0.008 | 0.016 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".