Longitudinal evaluation of the metabolic response of a tumor xenograft model to single fraction radiation therapy using magnetic resonance spectroscopy
Bibliographic record
Abstract
Proton magnetic resonance spectroscopy (MRS) was used to evaluate the metabolic profile of human glioblastoma multiform brain tumors grown as xenografts in nude mice before, and at multiple time points after single fraction radiation therapy. Tumors were grown over the thigh in 16 mice in this study, of which 5 served as untreated controls and 11 had their tumors treated to 800 cGy with 200 kVp x-rays. Spectra were acquired within 24 h pre-treatment, and then at 3, 7 and 14 d post-treatment using a 9.4 T animal magnetic resonance (MR) system. For the untreated control tumors, spectra (1-2 per mouse) were acquired at different stages of tumor growth. Spectra were obtained with the PRESS pulse sequence using a 3 × 3 × 3 mm(3) voxel. Analysis was performed with the LCModel software platform. Six metabolites were profiled for this analysis: alanine (Ala), myo-inositol (Ins), taurine (Tau), creatine and phosphocreatine (Cr + PCr), glutamine and glutamate (Glu + Gln), and total choline (glycerophosphocholine + phosphocholine) (GPC + PCh). For the treated cohort, most metabolite/water concentration ratios were found to decrease in the short term at 3 and 7 d post-treatment, followed by an increase at 14 d post-treatment toward pre-treatment values. The lowest concentrations were observed at 7 d post-treatment, with magnitudes (relative to pre-treatment concentration ratios) of: 0.42 ± 24.6% (Ala), 0.43 ± 15.3% (Ins), 0.68 ± 27.9% (Tau), 0.52 ± 14.6% (GPC+PCh), 0.49 ± 21.0% (Cr + PCr) and 0.78 ± 24.5% (Glu + Gln). Control animals did not demonstrate any significant correlation between tumor volume and metabolite concentration, indicating that the observed kinetics were the result of the therapeutic intervention. We have demonstrated the feasibility of using MRS to follow multiple metabolic markers over time for the purpose of evaluating therapeutic response of tumors to radiation therapy. This study provides supporting evidence that metabolite/water concentration ratios have the potential to be used as biomarkers for the assessment of the response to therapy.
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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) | 0.001 | 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 | 0.000 | 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".