The quantitative assessment of microvascular obstruction size using first-pass perfusion cardiac MR
Bibliographic record
Abstract
The presence and absolute amount of microvascular obstruction (MO) are associated with adverse left ventricular remodelling and prognosis in patients with acute myocardial infarction. MO can be detected with cardiovascular magnetic resonance imaging (CMR) using the technique of first pass perfusion imaging, late contrast enhanced CMR or early contrast enhanced CMR. It has not been shown which standardized definition of hypoenhancement related to the signal of remote myocardium is appropriate to evaluate the presence and the extent of MO on first pass perfusion images. We studied 52 patients with reperfused acute myocardial infarction which showed MO defined as persistent subendocardial hypoenhancement on rest perfusion images. We analyzed rest first-pass perfusion images, early contrast enhanced images and late contrast enhanced images scanned in a 1.5-T magnetic resonance imaging system. The size of MO was measured on rest perfusion images visually and quantitatively using signal intensity (SI) below 2SD and 3SD of remote myocardium as a threshold. The size of MO was also measured visually on early contrast enhanced images and quantitatively on late contrast enhanced images quantitatively defined as the area which did not show SI more than 5 SD above the remote myocardium surrounded by abnormal enhancement. On rest perfusion images, standardized analysis using the threshold of −2SD of remote myocardium showed good agreement with visual analysis (ICC= 0.793). Mean MO size using threshold of −2SD of remote myocardium was not significantly different from those by visual assessment (2.22±1.25 cm and 2.40±1.25 cm , p=N.S.), whereas those using threshold of −3SD of remote myocardium was significantly smaller (1.00±0.85 cm , p<0.05). MO size analyzed by early contrast enhanced images showed good agreement with visual analysis on perfusion images (ICC=0.881). Mean MO size assessed by late contrast enhanced images was significantly smaller than those on by visual analysis on perfusion images (1.16±1.21 cm and 2.40±1.27 cm , p<0.005). In patients with acute, reperfused MI, standard late enhancement images underestimate the size of myocardial areas with microvascular obstruction. Using a cutoff of 2 SD below mean SI of remote myocardium, rest perfusion images should be used to quantify the extent of microvascular obstruction.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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".