Construction and evaluation of a switch‐tuned <sup>13</sup>C ‐ <sup>1</sup>H birdcage radiofrequency coil for imaging the metabolism of hyperpolarized <sup>13</sup>C‐enriched compounds
Bibliographic record
Abstract
PURPOSE: To construct a switch-tuned (13) C - (1) H birdcage radiofrequency (RF) coil system capable of metabolic imaging of hyperpolarized (13) C-enriched metabolic probes for co-registration with MRI morphology using protons. MATERIALS AND METHODS: The switch-tuned coil was constructed using PIN diodes for rapid switching of the resonant frequency of the coil. Identical, single-tuned, (1) H and (13) C birdcage RF coils have also been constructed for comparison of imaging performance. A (13) C receive-only surface RF coil has been integrated with the switch-tuned coil for transmit-only, receive-only operation (TORO) to increase local (13) C signal for improved signal-to-noise ratio (SNR). RESULTS: The SNR achieved with the switch-tuned coil in transmit/receive mode was 87% that of the single-tuned (1) H coil. For (13) C imaging, the SNR for the switch-tuned coil was 55% that of the single-tuned (13) C coil. TORO operation of the switch-tuned coil with the surface coil increased SNR for by a factor of 4.2 over transmit/receive operation of the switch-tuned coil alone. CONCLUSION: A surface coil can be integrated with a switch-tuned (13) C - (1) H coil for (13) C TORO operation producing improved SNR. In vivo metabolic imaging of [1-(13) C]pyruvate in a rat model of glioma is demonstrated using TORO operation, which is co-registered with (1) H-imaged anatomy.
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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 | 0.000 |
| 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 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".