Contamination of single‐voxel multiple quantum filters by external water signals arising from intermolecular multiple quantum coherences
Bibliographic record
Abstract
Multiple-quantum filtered pulse sequences simplify overlapping metabolite spectra by the elimination of peaks from uncoupled spin species, most notably from methyl groups and water, and the minimization of unwanted coupled-spin peaks. However, it is shown in this study that a significant contaminant water signal can pass through this family of filters in the form of intermolecular multiple-quantum coherences. An imaging evaluation of a single-voxel multiple quantum filter experiment confirms that the water contamination is excited from outside of the voxel of interest, thus having an increased potential for broad spectral contamination. Phantom and in vivo experiments at 3.0 T are used to illustrate, first, significant water contamination of a single-voxel double quantum filter experiment optimized for the observation of glutamate, and second, the elimination of the unwanted water signal with conventional phase cycling and optimized filter gradient orientations.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 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 | 0.000 | 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 teacher head, 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".