Reversed halo sign in acute pulmonary embolism and infarction
Bibliographic record
Abstract
BACKGROUND: The reversed halo sign, originally described in cryptogenic organizing pneumonia, has been observed in a variety of pulmonary diseases, including pulmonary embolism (PE). PURPOSE: To describe the computed tomographic (CT) findings in patients with the reversed halo sign and acute PE at initial presentation and in subsequent scans. MATERIAL AND METHODS: Contrast-enhanced CT examinations of 12 patients with the reversed halo sign and acute PE were analyzed retrospectively. The diagnosis of pulmonary embolism was made by CT angiography in 11 cases and by a routine contrast-enhanced scan of the chest in the other case. Follow-up scans of seven patients and follow-up radiographs of two patients were also examined retrospectively. The average age of the patients was 49 years (range, 21-80 years). Seven (58%) patients were women. Six patients had no significant medical history, and six patients had deep venous thrombosis initially. RESULTS: The reversed halo sign was observed as a single lesion in 10 patients; in two patients, two lesions were found. The lesions, all pleural-based, occurred more frequently in the lower lobes and were associated with acute thromboemboli in segmental and subsegmental pulmonary arteries of the corresponding segment. Ten (10/14, 71%) lesions displayed an ellipsoid configuration, two (2/14, 14%) had a pyramidal shape, and two involved an almost entire pulmonary segment. The average largest dimension was 3.9 cm (range, 2.1-6.7 cm). All lesions subtended one or more bronchovascular bundles; three (3/14, 21%) showed air-bronchograms, and a thromboembolus was identified in the subtended arteries in nine (9/14, 64%) lesions. In succeeding CT scans (eight lesions) and follow-up radiographs (three lesions), the lesions became smaller, and the majority evolved into pleural-based linear scars by 7 months. CONCLUSION: The reversed halo sign very likely corresponds to pulmonary infarction in patients with acute PE. Its recognition may have important clinical implications.
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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 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".