Long TE STEAM and PRESS for estimating fat olefinic/methyl ratios and relative ω‐3 fat content at 3T
Bibliographic record
Abstract
Background Fat olefinic/methyl ratios provide a measure of fat unsaturation. The methyl resonance linewidth is altered with the presence of ω‐3 fat. Purpose To optimize stimulated echo acquisition mode (STEAM) and point resolved spectroscopy (PRESS) echo times (TE) at 3T to 1) improve olefinic/methyl ratios and 2) enable relative ω‐3 fat content assessment. Study Type Technical development on phantoms and healthy volunteers. Population Nine edible oils and four healthy volunteers (tibial bone marrow). Field Strength/Sequence STEAM (mixing time = 20 msec) and PRESS sequences at 3T. High‐resolution oil spectra at 16.5T. Assessment 3T STEAM and PRESS olefinic/methyl ratios as a function of TE were compared to 16.5T measures for the oils, and to a literature‐deduced value for tibial bone marrow. Oil methyl linewidths were calculated at each TE to investigate correlation with expected ω‐3 fatty acid content. Statistical Tests Percent differences were calculated between oil olefinic/methyl ratios obtained at 3T and 16.5T. Linear regression R2 values measured correlation of methyl linewidth to ω‐3 content. Results STEAM, TE = 120 msec, resulted in average oil olefinic/methyl ratios that differ by about –4.8% compared to high‐resolution ratios. Tibial bone marrow olefinic/methyl ratios differ by –1.8% compared with literature‐obtained ratios. PRESS, TE = 180 msec, resulted in oil ratios that differ by 7.8% and tibial bone marrow ratios that differ by 0.2%. A TE of 160 msec for both STEAM and PRESS enabled relative levels of oil ω‐3 fatty acid content to be estimated (R2 values ≥0.9). Data Conclusion STEAM, TE = 120 msec (mixing time = 20 msec), and PRESS, TE = 180 msec, optimally estimated olefinic/methyl ratios. STEAM and PRESS, TE = 160 msec, enable relative oil ω‐3 fatty acid estimation from methyl linewidths. Level of Evidence: 1 Technical Efficacy Stage 1 J. Magn. Reson. Imaging 2017.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.007 | 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".