Human whole‐blood relaxometry at 1.5T: Assessment of diffusion and exchange models
Bibliographic record
Abstract
Human whole-blood relaxometry experiments were performed to allow the prediction of blood signal changes with blood oxygen saturation (Y) and refocusing interval (tau180). Such predictions are particularly relevant for spin-echo (SE) blood oxygenation level-dependent (BOLD) experiments and a recently proposed noninvasive fMRI method for measuring cerebral blood volume (CBV). Ensemble fitting of the entire set of T2 estimates, obtained over an extensive range of Y and tau180 values, was performed with the use of both a fast chemical exchange model and a model of diffusion in weak magnetic field inhomogeneities. The diffusion modeling resulted in a large reduction in the residual sum-of-squares compared to the fast exchange modeling. The longitudinal relaxation rate decreased linearly with Y, and increased with hematocrit. The results support the application of the recently reported diffusion model to describe deoxyhemoglobin (dHb)-induced blood transverse relaxation rate enhancement at 1.5 T.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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) | 0.000 | 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 teacher head, 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".