CBF imaging and global CBF quantification in normal rats using dedicated pinhole SPECT system
Bibliographic record
Abstract
This work is intended to evaluate [99mTc]-radiolabeled pharmaceuticals for brain perfusion measurements in rats using pinhole SPECT. Our experiments aim to obtain quantitative data in normal animals. A dedicated Anger type rotating gamma camera (field of view 170 mm 170 mm, 25 photomultiplicators) was used with 1.5 mm hole diameter's pinhole collimator (Gaede Medizinsysteme Gmbh, Freiburg, Germany). 15 to 20 mCi of [99mTc]-hexamethyl propylamine oxime (Amersham Health, Little Chalfont, UK), was administered to 10 Wistar adult rats under general gaseous anesthesia (isoflurane 2%), through intravenous femoral catheter. During tracer administration, 120 planar images of 0.5 s were recorded. Ten minutes after, 48 projections of 1 min were acquired over a 180 dorsal arc. A specific cone beam algebraic reconstruction algorithm, taking into account distorsion of projection through pinhole, was employed leading to reconstructed voxel's sizes of 0.34 mm3. Micro-CT (eXplore LOCUS, General Electric Medical Systems, London, Canada) images of the same animal were fused with SPECT data for anatomical registration. Using the Patlak formalism, modified by Matsuda, we calculate global CBF values for each cerebral hemisphere. Images' contrast reflects normal tracer's uptake in the different cerebral territories. Signal to noise ratios in human and rat brain perfusion's images are comparable. Calculation leads to a gCBF of 110.1 ml/100g/min 11.4 value in the range of reference data. This technique could be used to assess CBF in pathological conditions in rats.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| 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".