MRI ParaCEST agents that improve amide based pH measurements by limiting inner sphere water T<sub>2</sub>exchange
Bibliographic record
Abstract
A series of Dy3+ and Tm3+ tetra-substituted DOTAM paraCEST agents incorporating para-substituted anilines has been synthesized and their paraCEST and relaxation properties evaluated. The response of selected agents (aniline and p-methoxyaniline) to changes in pH near the physiological range has also been studied. A crystal structure of Tm3+-p-OMe agent indicates a TSAP geometry with the absence of an inner sphere water molecule (denoted as TSAP'), which is thought to be due to the bulky nature of the amide nitrogen substituent. Two distinct amide signals are observed in the CEST spectrum for this compound, one for each of the isomers that exist in solution: SAP and TSAP with the larger chemical shift centred at −83 ppm compared to bulk water. Due to the non-optimal inner sphere water exchange, these agents produce minimal shortening of T1 and T2 relaxation time constants and therefore decrease relaxation induced signal losses during imaging.
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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) | 0.001 | 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".