Hyperpolarized 129Xe Diffusion-weighted MRI for Lung Morphometry of Bronchopulmonary Dysplasia
Bibliographic record
Abstract
Bronchopulmonary dysplasia (BPD) is a disease that affects very prematurely born infants requiring ventilatory support and supplemental oxygen from birth. Despite advances in neonatal critical care, about 40% of very preterm infants develop BPD, characterized by alveolar simplification and microvascular stunting. Chronic sequelae of the disease persist into adulthood, reducing quality of life and exacting a significant toll on the healthcare system. Hyperoxia exposure followed by intermittent hypoxia in newborn rats mimics features of human BPD, specifically alveolar simplification. Alveolar simplification is morphometrically quantified by the mean linear intercept (MLI) that is based on hand-counting of intercepts from a limited number of representative histological sections and fields. With the advent of hyperpolarized (HP) gas magnetic resonance (MR) imaging, non-invasive imaging of terminal airway structure and function is achievable in vivo. HP 129Xe MR morphometric imaging exploits diffusion weighting along with a theoretical cylinder model of the terminal airways, to characterize the microstructure (eg. the terminal airway chord length, Lm) of the terminal airways. In this thesis, hyperpolarized 129Xe MR morphometric imaging was applied to characterize the microstructural changes associated with an O2 exposure rat model of BPD. Hyperoxia exposures consisted of either 60% or 85% O2 from post-natal day (PND) 1 – 7, followed by 60% O2 from PND 8-14. MR morphometry was performed and microstructural changes were compared with histology obtained from the same rats post-imaging. Lm and MLI were moderately correlated (r2 = 0.34, p = 0.0028), and MLI was increased by 11.3 ± 4.6µm in the 85% O2 exposed group compared to the control group, while Lm showed similar trends. Regional compliance was also estimated, assessing lung microstructural elasticity by performing morphometry at multiple peak-inspiratory-pressures. On average, alveolar compliance values scaled to a whole lung (19.1±15.1mL/cmH2O) were two orders of magnitude larger than conventional whole lung compliance obtained in the same animals (0.36±0.08mL/cmH2O) in a cohort of healthy rats. The two quantities were moderately correlated (r2 = 0.63, p = 0.019). HP 129Xe MR morphometric imaging affords non-invasive regional characterization of the lung microstructure and may be useful for the long term tracking of BPD in the clinic.
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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 | 0.000 | 0.000 |
| 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 | 0.001 |
| 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".