In vivo double quantum filtered sodium magnetic resonance imaging of human brain
Bibliographic record
Abstract
PURPOSE: Sodium signal from ordered environments can be selectively detected using a double-quantum magic angle (DQ-MA) sequence. This study presents the first DQ-MA sodium images of the human brain and evaluates the effect of preparation time (τ) on the signal. THEORY AND METHODS: Three phantoms of saline, agar gel, and xanthan gum were used to test the correct functioning of the DQ-MA sequence. Five healthy volunteers were imaged using DQ-MA with varying τ to determine the optimal preparation time. DQ-MA images were acquired with 1 or 2 averages and nominal resolution of 15 mm isotropic in 3.5 or 7 min, respectively. In addition, higher nominal resolution (8.4 mm isotropic) DQ-MA images were acquired from another subject in 48 min. Post hoc simulations were performed to explain the effect of τ on imaging results. RESULTS: The DQ-MA sequence generates signal from only the xanthan gum phantom, correctly suppressing signal from environments in which the time-averaged quadrupolar interaction is expected to be zero (saline, agar). This sequence generates signal throughout the brain with maximum detection when τ=3 ms. CONCLUSION: The existence of DQ-MA signal in the human brain indicates the presence of sodium nuclei in ordered environments and provides a novel contrast mechanism.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 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".