OP29.07: Non‐invasive <i>in utero</i> measurements of placental oxygen transport using <scp>MRI</scp>
Bibliographic record
Abstract
To investigate the use of MRI to assess placental function in terms of placental-fetal oxygen (O2) transport in utero. Eight women with normal pregnancies were scanned using a 1.5 T Siemens MRI system. To measure placental-fetal O2 transport, blood flow (Q) and oxygen content (C) were measured in blood vessels supplying (uterine arteries and fetal descending aorta) and draining (uterine, ovarian and umbilical veins) the placenta. Phase contrast MRI was used to measure Q. Vascular blood T1 and T2 MRI relaxometry were used to measure oxygen saturation and hematocrit to derive C. The oxygen delivery (Do2) and return (Ro2) were calculated as C*Q. Oxygen consumption (Vo2) was calculated using the arterio-venous difference in C of blood supplied to and drained from an organ and multiplying it by Q. All oxygen transport measures were indexed to fetal weight, which was calculated from the 3D MRI acquisition of the uterus. The mean placental-Vo2 was 4.1 ml/min/kg, which accounted for 33.9% of the total placental-fetal-Vo2. The mean fetal-Vo2 was 8.0 ml/min/kg and the mean placental-to fetal-Vo2 ratio was 0.53 (see table 1).
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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 | 0.001 |
| 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 | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".