The Magnetic Resonance Imaging “Spot” Sign: A Sign of Imminent Intracranial Hemorrhage?
Bibliographic record
Abstract
A 53-year-old man who underwent recent mitral valve repair and tricuspid valve annuloplasty 3 months prior presented with transient mild left-sided facial droop and dysarthria.He had a National Institute of Health Stroke Scale (NIHSS) of 1.Initial unenhanced CT and CT angiogram (Figure 1A and B) demonstrated acute infarct in the right insula secondary to a filling defect in right distal middle cerebral artery (MCA).MRI vessel wall imaging was performed 12 h after initial CT to clarify the etiology of this filling defect and was concluded an embolus as there was no evidence of wall thickening or enhancement.Limited brain sequences (Figures 1C-H) performed concurrently demonstrated high fluid-attenuated inversion recovery (FLAIR) signal in the right insula, compatible with the infarct.There was additionally unexpected sulcal T1 and FLAIR hyperintensity overlying right frontal convexity and an area of contrast blush in the right occipital lobe without other corresponding abnormality allowing for lack of diffusion weighted imaging (DWI) and blood-sensitive sequences on this first MRI.While awaiting cardiac investigations, the patient developed visual field defect, prompting the second MRI brain with contrast (Figure 2).This MRI demonstrated a parenchymal hematoma in the right occipital lobe, with a focal area of enhancement centrally.The sulcal T1 and FLAIR hyperintensity were confirmed as blood products on the susceptibility weighted imaging (SWI) sequence, and there was restricted diffusion in the right insula, confirming the right MCA infarct.A subsequent transesophageal echocardiography demonstrated vegetation in the heart valves and he was commenced on moxifloxacin and doxycycline for 6 weeks.A digital subtraction angiography (DSA) was performed to exclude a mycotic aneurysm causing the parenchymal hematoma with this knowledge and was negative.He remained well without progression or development of new focal neurological deficit and was discharged with an NIHSS score of 0, 12 days after initial presentation.The "spot" sign was first described on CT angiography by Wada et al. as a focus of contrast extravasation within a hematoma, shown to be predictor of hematoma expansion.1 Multiple case reports and studies have assessed and reported on the analogous MRI spot sign in intracerebral and subdural hematoma.2-
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".