Repairing Myelin After Irradiated Pediatric Brain Tumor: A Magnetization Transfer Imaging Analysis
Bibliographic record
Abstract
BACKGROUND: While exercise training and metformin treatment have demonstrated preliminary cognitive improvements in pediatric brain tumor (PBT) survivors, the neuronal mechanisms underlying their cognitive improvements are unclear. Diffusion-weighted metrics (e.g., fractional anisotropy [FA]) are commonly used to evaluate remyelination, but magnetization transfer imaging is thought to be more sensitive to myelin plasticity. METHODS: We compared white matter changes after exercise and metformin interventions by evaluating magnetization transfer ratio (MTR) and FA changes in irradiated PBT survivors who completed either an exercise (NCT01944761) or metformin pilot trial (NCT02040376) (30 participants: exercise n = 11, metformin n = 12, and control n = 7). Then, we explored correlations between MTR and cognitive outcomes. RESULTS: There were significant MTR changes in three brain regions (right forceps minor in both interventions, right inferior and superior longitudinal fasciculi in the exercise group), but no significant FA changes. MTR increases occurred in the right forceps minor in the exercise and metformin groups compared with the control group (p < 0.033), and in the superior longitudinal fasciculus in the exercise group compared with the control group (p = 0.016). Preliminary correlations between MTR and cognitive changes were not significant after correcting for multiple comparisons. CONCLUSIONS: Our results suggest that 12 weeks of exercise or metformin intervention may promote remyelination in PBT survivors in brain regions involved in memory and executive function, and there may be differences in the brain regions affected by each intervention. This work sets the stage for larger clinical trials to identify definitive differences in MTR and validate their association with cognition.
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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 | 0.001 | 0.001 |
| 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) | 0.001 | 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".