Manganese‐enhanced MRI of acute cardiac ischemia and chronic infarction in pig hearts: kinetic analysis of enhancement development
Bibliographic record
Abstract
To assess infarction development in pig hearts, Mn-enhanced and Gd-enhanced MRI were used. In domestic pigs (25-35 kg, n = 37), the first and second diagonal branches of the left anterior descending coronary artery were ligated to induce acute ischemia and infarction (ischemia+reperfusion) or chronic infarction of increasing duration (3- 28 days). Ex vivo experiments were performed on hearts perfused in the Langendorff mode with a 50:50 mixture of blood and Krebs-Henseleit buffer using a spin-echo sequence on a 7 T Bruker imaging system. Signal acquisition from the heart and two reference test tubes (H(2)O and H(2)O + 10 mM CuSO(4)) was gated by the left ventricular pressure wave. T(1)-weighted images of six 8 mm short-axis slices (2 mm interslice gaps) were obtained before and after the addition of 0.2 mM MnCl(2) every 5 min over a 30-45 min period. Signal intensities were normalized to those of the H(2)O reference and fitted by a monoexponential function. The rates of intensity increase and maximal increases were significantly lower in the ischemic/infarcted areas and showed a trend to rise on infarction progression. In vivo Gd-enhanced MRI (3 T Siemens scanner) and in vivo/ex vivo near-infrared imaging confirmed major Mn-enhanced MRI findings. Triphenyltetrazolium chloride staining revealed necrotic areas in all chronic infarctions and no necrosis after acute ischemia. We conclude that MnCl(2) highlights ischemic areas because of the low collateral flow characteristic of pig hearts, whereas in the infarcted areas with substantial perfusion, scar tissue components are important for contrast distribution.
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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".