Manganese‐52 positron emission tomography tracer characterization and initial results in phantoms and <i>in vivo</i>
Bibliographic record
Abstract
PURPOSE: Manganese(II) is employed as a contrast agent with magnetic resonance imaging (MRI) for study of neuronal activation in rats and mice. However, at the concentrations required for MRI, Mn may induce pharmacological or toxic effects. Positron emission tomography (PET) imaging of (52)MnCl2 at tracer doses has the potential to allow similar Mn studies as manganese-enhanced MRI while providing quantitative results and avoiding toxic effects. In this work, (52)MnCl2 is produced and characterized as a PET tracer in phantoms and in rats. METHODS: (52)MnCl2 was produced by proton irradiation of natural Cr foil and separated by column chromatography. Images were acquired on a Siemens Focus 120 small animal PET scanner. Phantom images were acquired to assess uniformity, resolution, cascade background correction, and count rate linearity. Images of rats were also acquired after systemic and intracerebroventricular (ICV) administration of (52)MnCl2 to investigate Mn(II) distribution in vivo. RESULTS: Irradiation yield was 74.6 ± 8.5 kBq/μA min (52)Mn at end of bombardment with initial specific activity of at least 3.5 MBq/nmol. (52)Mn PET images show similar uniformity and resolution to (18)F. (18)F based detector efficiency normalization is adequate for (52)Mn imaging. Subtraction of a rescaled random events distribution from sinogram data is effective for cascade correction of (52)Mn PET data. After systemic injection, (52)Mn appears in structures throughout the body of rats, including bones, liver, intestines, and the pituitary gland, but does not appear detectably throughout the brain. After ICV injection, (52)Mn remains in the brain and spinal cord. CONCLUSIONS: (52)Mn is a promising tracer for small animal PET imaging, yielding image quality comparable to (18)F. Potential applications include studies similar to Mn-enhanced neuronal MRI, and in other organ systems including bones, spinal cord, and the digestive tract.
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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) | 0.000 | 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".