Perfusion measures for symptom severity and differential outcome of revascularization in limb ischemia: Preliminary results with arterial spin labeling reactive hyperemia
Bibliographic record
Abstract
Background Previously, a theoretical model based on microvascular physiology was established to facilitate the interpretation of calf perfusion dynamics recorded by arterial spin labeling (ASL). Purpose To investigate the clinical relevance of novel perfusion indices by comparing them to the symptoms, response to revascularization, and short‐term functional outcome in patients with peripheral arterial disease (PAD). Study Type Prospective cohort study. Population Nineteen patients with PAD. Field Strength/Sequence Pulsed ASL at 3T. Assessment The mid‐calf reactive hyperemia induced by 2 minutes of arterial occlusion was recorded in PAD patients. The perfusion responses were characterized by the peak, time‐to‐peak, and physiological model‐derived indices including the baseline perfusion fr, arterial resistance Ra, and compliance Ca, and sensitivity gATP and response time τATP of downstream microvasculature to metabolic stress. These indices were compared to the disease severity and outcome within 6 months after revascularization assessed by self‐reported symptoms and the ankle‐brachial index. Disease severity was categorized as asymptomatic, claudication, or critical limb ischemia. The outcome was categorized as symptom resolved or limited improvement. Statistical Tests Severity and outcome groups were compared using Mann–Whitney and Kruskal–Wallis tests with Holm–Sidak adjustments. Results The peak perfusion decreased and model arterial resistance increased progressively with increasing severity of limb ischemia (P = 0.0402 and 0.0413, respectively). Eleven patients had a successful endovascular procedure, including six patients who had symptoms resolved, four patients who had remaining leg pain, and one patient lost to follow‐up. The subjects with limited improvement had significantly lower preintervention microvascular sensitivity gATP than those with symptoms resolved (8.72 ± 1.46 vs. 4.93 ± 0.91, P = 0.0466). Data Conclusion ASL reactive hyperemia reflects multiple aspects of the pathophysiology. Measures of macrovascular arterial disease are related to the manifested symptom severity, whereas preintervention gATP associated with microvascular dysfunction is related to prognosis following revascularization. Level of Evidence: 1 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2018;47:1578–1588.
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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 | 0.000 |
| 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) | 0.001 | 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".