Interindividual, repositioning, and time‐of‐day effects on single voxel proton MR spectroscopy of the anterior cingulate cortex
Bibliographic record
Abstract
PURPOSE: To measure interindividual, repositioning, and time-of-day effects of single voxel PRESS (Point RESolved Spectroscopy) proton magnetic resonance spectroscopy ((1)H-MRS) acquisition of the anterior cingulate cortex (AC) in healthy human subjects. MATERIALS AND METHODS: AC (1)H-MRS measurements were performed in 15 healthy adult volunteers using a short echo PRESS sequence (GE Healthcare 3 Tesla, TE/TR = 30/2500 ms, 192 acquisitions, 6 cm(3) voxels). For each individual, a total of eight spectra were obtained during two identical scanning sessions separated by 3.5 h. In each, two consecutive AC spectra were acquired. After the first two scans, the subject left the scanner, then immediately returned for repositioning and acquisition of two more consecutive spectra. The subject then left the imaging centre to return 3.5 h later for a repeated procedure. Spectroscopic postprocessing was done using LCmodel. Interindividual, repositioning and time-of-day effects were measured using restricted maximum likelihood (REML) models of variance components analysis, where response variables were levels of creatine/phosphocreatine (Cr), N-acetyl-aspartate (NAA), myo-inositol (mI), choline (Cho), and the glutamate-glutamine complex (Glx). RESULTS: Interindividual effects were markedly higher than time-of-day and repositioning effects for all metabolites. CONCLUSION: Our findings show that (1)H-MRS measurements of the AC are sensitive to interindividual differences, while time of day and repositioning are markedly less important.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 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 | 0.000 |
| 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".