Dihydrotetrabenazine positron emission tomography imaging in early, untreated Parkinson's disease
Bibliographic record
Abstract
OBJECTIVE: To determine the sensitivity of positron emission tomography with 11C-labeled dihydrotetrabenazine (DTBZ) to the nigrostriatal changes associated with early, untreated Parkinson's disease (PD), and to determine the correlation between any regionally reduced DTBZ binding and the major motor features of PD. METHODS: Untreated patients with early PD (n = 27) and age-matched control subjects (n = 33) underwent DTBZ/positron emission tomography scanning to measure binding to the presynaptic type 2 vesicular monoamine transporter site in dopaminergic neurons in basal ganglia regions. Clinical symptoms were rated with the Unified Parkinson's Disease Rating Scale. RESULTS: Mean striatal DTBZ binding values in the patient group were decreased as compared with control subjects (p < 0.001) in all regions examined. The difference between patients and control subjects was most marked in the midputamen, where only one patient had DTBZ binding within 3 standard deviations of the control mean. Bradykinesia and rigidity scores correlated with DTBZ binding in the contralateral midputamen region, particularly for the clinically least affected limbs. Tremor scores showed no significant correlation. INTERPRETATION: Reduced striatal binding of DTBZ is associated with early PD. Tremor appears to be only partially related to presynaptic dopaminergic function and may have a mechanism differing from that of symptoms such as bradykinesia. The method appears to be most sensitive in mildly affected individuals with a possible "floor" effect that may limit the degree of additional change occurring once more severe clinical symptoms are evident.
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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 | 0.000 |
| 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 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".