Optimized PRESS sequence timings for measuring glycine at 9.4 T: demonstration <i>in vivo</i> in rat brain
Bibliographic record
Abstract
The objective of this work is to optimize the Point Resolved Spectroscopy (PRESS) sequence echo times, TE 1 and TE 2 , for glycine (Gly) detection at 9.4 T, a common field strength at which animal magnetic resonance studies are conducted. The two uncoupled protons of Gly resonate at about 3.55 ppm and their peak is largely overwhelmed by signal from the strongly coupled protons of myo-inositol (mI) which resonate in the Gly spectral region (3.52–3.57 ppm). J-coupling evolution of the mI protons was characterized at 9.4 T by numerical calculations and by acquiring PRESS spectra with various {TE 1 , TE 2 } combinations from a 50 mM mI phantom. A {TE 1 , TE 2 } combination of {60 ms, 100 ms} minimized mI signal in the Gly spectral region and its efficacy was verified on mI and Gly phantom solutions and on rat brain in vivo . LCModel was employed to analyse in vivo spectra. The average Gly concentration from three rat brains was found to be 1.35 mM assuming a creatine (Cr) concentration of 8 mM. LCModel Cramér-Rao Lower Bound values for Gly ranged between 15% and 20%.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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 | 0.001 | 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".