Increased extra-cardiac background uptake on immediate and delayed post-stress images with 99Tcm sestamibi: determinants, independence, and significance of counts in lung, abdomen and myocardium
Bibliographic record
Abstract
Extra-cardiac activity on stress scans with 99Tcm sestamibi (MIBI) may influence scan interpretation. Lung uptake represents a potential sign of severe disease, whereas abdominal uptake may interfere with visualization of myocardial defects. We assessed myocardial, lung and infradiaphragmatic abdominal activity on images at 4 min (IMM) and 1 h (DEL) post-stress in 1800 consecutive studies. Potential variation among patients in organ activity was reduced with a weight-based dosing protocol. Multifactorial analysis was used to compare organ activity, and background ratios, i.e lung/heart or abdomen/heart, on stress images to (1) result of tomography, (2) peak workload, and (3) protocol (same-day versus separate-day rest/stress). Lung/heart ratios were primarily related to tomographic abnormalities, and abdomen/heart ratios to low stress workload; neither was related to protocol, and the two measurements appeared independent. Elevated lung/heart ratios (compared to angiographic normals), present on 16% and 10% of IMM and DEL images respectively, were determined primarily by increases in regional lung activity. Lung activity (normalized for dose) was higher in cases with disease than in normals (P<0.0001 as assessed by tomography, P<0.05 in the subset with correlating angiography). Increased abdominal/heart ratios derived primarily from increased abdominal activity, but were partially dependent on reciprocal decreases in myocardial activity. Elevated MIBI lung uptake ratios on abnormal scans can be attributed primarily to increased lung persistence of the radiotracer, and would thus be consistent with their use as a sign of left ventricular failure. Elevated abdominal background is associated with both higher splanchnic activity and lower myocardial activity, and is a non-specific finding related to suboptimal exercise intensity.
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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 | 0.001 |
| 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".