OC15.05: Prospective study of intracranial translucency and posterior fossa in normal fetuses at 11–13 weeks gestation
Bibliographic record
Abstract
1. To evaluate the ability of sonographers to confidently identify intracranial translucency (IT) at 11–13 weeks 2. To report on qualitative and quantitative assessment of the posterior fossa on stored IT images Following specific training for IT visualization, 10 sonographers prospectively identified IT during nuchal translucency ultrasound, noting whether IT was present, absent or uncertain. If IT was absent/uncertain, they documented the reason as spina bifida or inadequate image (with reasons for inadequate image). All uncertain or absent IT cases were reviewed by an experienced physician. Stored IT images of the remaining cases were reviewed by another observer for qualitative and quantitative assessment of brainstem diameter (BSD) and brainstem-occipital bone diameter (BSOBD). A random sample of 50 cases was reviewed by 2 observers for intra and interobserver variability. Intraclass correlation coefficients (ICC) were generated. Between June and Sept. 2011, 330 women were recruited; 19 excluded with fetal demise, multiple pregnancy or fetal anomaly. Median maternal age was 33 years and median gestational age 12.4 weeks. Of 291 with 18–22 week scan, none had spina bifida. IT was documented as present in 280 (96%), and uncertain in 11 (4%), due to inadequate image [the top 3 reasons were fetal position (n = 8), obesity (n = 5) and retroverted uterus (n = 4)]. Fetal position and gestational age were significantly associated with IT visualization. There was substantial intra and interobserver agreement for measurements of BSD (ICC = 0.62, 0.66) and BSOBD (ICC = 0.80, 0.77). Both qualitative and quantitative assessment of the BSD/BSOBD ratio confirmed previous observations that it is < 1 in normal fetuses. Bland Altman analysis revealed negligible intra and interobserver differences in BSD and BSOBD measurements. IT can be prospectively identified in 96% of normal fetuses, suggesting that it is feasible to introduce the technique at 11–13 weeks. Qualitative assessment can reliably determine normal BSD/BSOBD ratio.
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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 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".