Abstract WP339: Arterial Spin Labelling Cerebral Perfusion Measurements Demonstrate Normal Blood Flow in Subacute Intracerebral Hemorrhage Patients
Bibliographic record
Abstract
Introduction: Perihematomal hypoperfusion in acute intracerebral hemorrhage (ICH) has been demonstrated using CT perfusion. Although blood pressure (BP) reduction does not appear to impact perihematomal Cerebral Blood Flow (CBF), measurements using contrast are limited to a single time point. It has also been shown that up to 41% of ICH patients develop subacute diffusion-weighted imaging (DWI) lesions on MRI. Arterial Spin Labelling (ASL) is an magnetic resonance imaging (MRI) technique that allows measurement of CBF without a contrast agent, making it suitable for serial measurements. We assessed CBF in ICH patients using ASL and tested the hypothesis that perihematoma perfusion is related to BP. Methods: Patients with CT scan confirmed ICH were prospectively recruited within 6 hours of symptom onset. Acute systolic BP (SBP) targets were randomly assigned as part of an ongoing trial. The SBP target remained blinded for this analysis. Patients were assessed with ASL at 48 hours post ICH. The perihematoma region was defined using co-registered susceptibility weighted images to delineate the hematoma border. Relative CBF (rCBF) was calculated as a ratio of the ipsilateral to contralateral ASL measurements. Results: Perfusion was measured in 6 ICH patients, none of whom had DWI lesions, 55.38 (43.72, 59.75) hours after onset. Median 48 hour hematoma volume was 23.40 (18.10, 99.90) ml. Mean±SD SBP at 48 hours was 140.20 ± 10.64 mmHg. Mean perihematomal rCBF was 0.95±0.37. Mean hemispheric rCBF was 0.95 ± 0.17. Perihematomal and hemispheric CBF was not lower in the side of the hematoma ( p >0.583). Hematoma size was unrelated to rCBF (perihematomal R=0.039, 95% CI [-0.880, 0.959], p =0.682; hemispheric R=0.00, 95% CI [-0.005, 0.006], p =0.932). Systolic BP at the time of the scan, difference between baseline SBP and SBP at the time of the scan, and time spent with SBP <140 mmHg were all not associated with perihematomal or hemispheric rCBF ( p >0.170). Conclusion: It is feasible to measure perihematoma and hemispheric perfusion in ICH patients using ASL, which may be useful for serial CBF assessment, particularly in patients with MRI evidence of ischemia.
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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 | 0.000 | 0.000 |
| 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) | 0.003 | 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".