Does a Positive Pittsburgh Compound B Scan in a Patient With Dementia Equal Alzheimer Disease?
Bibliographic record
Abstract
IMPORTANCE: The clinical role of amyloid brain positron emission tomographic imaging in the diagnosis of Alzheimer disease is currently being formulated. The specificity of a positive amyloid scan is a matter of contention. OBSERVATIONS: An 83-year-old Canadian man presented with a 5-year history of predominantly short-term memory loss and functional impairment. Clinical evaluation revealed significant, gradually progressive short-term memory loss in the absence of any history of strokes or other neuropsychiatric symptoms. The patient met clinical criteria for probable Alzheimer disease but had a higher than expected burden of white matter disease on magnetic resonance imaging. A positron emission tomographic Pittsburgh Compound B scan was highly positive in typical Alzheimer disease distribution. The patient died of an intracerebral hemorrhage 6 months after the assessment. Autopsy revealed cerebral amyloid angiopathy in the complete absence of amyloid plaques or neurofibrillary tangles. CONCLUSIONS AND RELEVANCE: This patient demonstrates that a positive Pittsburgh Compound B scan in a patient with clinical dementia meeting criteria for probable Alzheimer disease is not proof of an Alzheimer disease pathophysiological process. A positive Pittsburgh Compound B scan in typical Alzheimer disease distribution in a patient with dementia can be secondary to cerebral amyloid angiopathy alone.
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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 | 0.000 |
| 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 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".