Magnetic Resonance Imaging Angiography of Physiological and Pathological Pregnancy Placentas Ex Vivo: Protocol for a Prospective Pilot Study
Bibliographic record
Abstract
BACKGROUND: Preeclampsia (PE) and intrauterine growth restriction (IUGR) are 2 major pregnancy complications due to abnormal placental vasculogenesis. Data on whole fetoplacental vasculature are still missing; hence, these pathologies are not well understood. Ex vivo magnetic resonance imaging (MRI) angiography has been developed to characterize the human placental vasculature by injecting a contrast agent within the umbilical cord. OBJECTIVE: The primary objective of this study is to compare the placental vascular architecture between normal and pathological pregnancies. This study's secondary objectives are to (1) compare texture features on MRI between groups (normal and pathological), (2) quantitatively compare the vascular architecture between both pathological groups (pathological IUGR, and pathological PE), (3) evaluate the quality of the histological examination in injected placentas, and (4) compare vascularization indices to histological characteristics. METHODS: This is a prospective controlled study. We expect to include 100 placentas: 40 from normal pregnancies and 60 from pathological pregnancies (30 for IUGR and 30 for PE). Ex vivo MR image acquisition will be performed shortly after delivery and with preparation by injection of a contrast agent in the umbilical cord. The vascular architecture will be quantitatively described by vascularization indices measured from ex vivo MRI angiography data. Comparisons of vascularization indices and texture features in accordance with the group and within comparable gestational age will be also performed. After MR image acquisition, placental histopathological analysis will be performed. RESULTS: The enrollment of women began in November 2019. In view of the recruitment capacity of our institution and the availability of the MRI, recruitment should be completed by March 2022. As of November 2021, we enrolled 70% of the intended study population. CONCLUSIONS: This study protocol aims to provide information about the fetal side of placental vascular architecture in normal and pathological placenta through MRI. TRIAL REGISTRATION: Clinicaltrials.gov NCT04389099; https://clinicaltrials.gov/ct2/show/NCT04389099. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/35051.
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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 | 0.008 | 0.004 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.015 | 0.005 |
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".