P2‐177: CLINICAL IMPACT OF REPEATED FDG‐PET IN THE DIFFERENTIAL DIAGNOSIS OF ATYPICAL DEMENTIAS
Bibliographic record
Abstract
With the potential emergence of disease specific therapies, accurate imaging methods are needed to allow early diagnosis, especially in complex/atypical dementias, where incertitude often delays treatment initiation. It is now increasingly accepted that18F-deoxyglucose Positron Emission Tomography (FDG-PET) helps improve diagnostic accuracy in complex/atypical dementias. However, no authors have studied the added value of a second FDG-PET when clinicians still face diagnostic incertitude after extensive clinical evaluation and an equivocal first FDG-PET. Furthermore, there are no guidelines as to when this would be appropriate over the time course of the disease. The goal of this project was therefore to retrospectively evaluate the clinical impact of repeated FDG-PET in the diagnostic process of complex/atypical dementias in a tertiary care memory clinic. We retrospectively evaluated 59 cases who had undergone ≥2 FDG-PET in the process of their clinical evaluation. An experienced cognitive neurologist (RWB) was asked to rate 'Diagnostic Certitude' (Very low: 20%; Low: 40%; Fair: 60%; High: 80%; Very High: 100%) before PET2 and after PET2, and rate this exam as 'Helpful', 'Helpless' or 'Confusing' on the basis of the entire patient's chart. We further assessed pre- and post-PET2 changes in cholinesterase inhibitors' prescription. PET2 conducted 20.8 months (SD: 12.4) after PET1 allowed a statistically (p<0,0001) and clinically significant increase in 'Diagnostic Certitude' from 63% (Fair) to 78% (High). PET2 was found helpful in 40/59 (68%) of the patients, helpless in 13/59 (32%), and confusing in 6/59 (10%). Despite a 7-month interval between the clinical evaluations surrounding PET2, average MMSE remained in the same range (24.4 and 23.8, respectively). Cholinesterase inhibitors (ChEIs) were initiated in 29% (10/35) of patient not already under an empirical treatment, and ceased in 2 cases with non-Alzheimer's metabolic profiles. In this study of 59 tertiary care complex/atypical dementia patients, the addition of a second FDG-PET to the diagnostic work-up significantly increased 'Diagnostic certitude'. The second PET conducted 1.5 years following the first PET was considered 'Helpful' by clinicians in 2/3 of cases, and allowed a more refined treatment. These results provide guiding evidence on the clinical utility of repeated FDG-PET imaging in complex/atypical dementia.
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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 | 0.002 | 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 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".