Midbrain iron content in early Parkinson disease
Bibliographic record
Abstract
<b>Background: </b> Parkinson disease (PD) is a progressive neurodegenerative disorder in which the major pathologic substrate is a loss of dopaminergic neurons from the lateral substantia nigra pars compacta (SNc). Our objective was to determine whether, in patients with early PD, SNc changes evident on MRI sequences sensitive to iron content corresponded anatomically to the pathologic changes reported previously, and to correlate these changes to the duration and severity of clinical manifestations of PD. <b>Methods: </b> Twenty-six untreated patients with early PD and 13 age- and gender-matched control subjects had MRI with a 3 tesla magnet using a multiple gradient echo sequence designed for rapid single-scan mapping of the proton transverse relaxation rate (<i>R<sub>2</sub>*</i>). <i>R<sub>2</sub>*</i> was calculated for midbrain and forebrain basal ganglia regions. Clinical features were rated with the Unified Parkinson9s Disease Rating Scale. <b>Results: </b> A difference in measured <i>R<sub>2</sub>*</i> values between patients and controls was observed in the lateral SNc (<i>p</i> ≤ 0.005). Linear regression indicated a correlation between the lateralized motor score from the clinically most affected side and <i>R<sub>2</sub>*</i> values from the opposite lateral SNc (<i>p</i> = 0.01). <b>Conclusions: </b> High field strength MRI demonstrates lateral substantia nigra pars compacta abnormalities in early Parkinson disease (PD) consistent with increased iron content and corresponding to the known distribution of neuronal loss occurring in this disorder. This may ultimately provide an imaging marker for disease progression in PD, although longitudinal studies are required. <b>GLOSSARY: </b><b>AC</b> = anterior commissure; <b>CN</b> = caudate nucleus; <b>GP</b> = globus pallidus; <b>LantGP</b> = left anterior GP; <b>LantPu</b> = left anterior Pu; <b>LlatSNc</b> = left lateral SNc; <b>LlatSNr</b> = left lateral SNr; <b>LmedSNc</b> = left medial SNc; <b>LmedSNr</b> = left medial SNr; <b>LpostGP</b> = left posterior GP; <b>LpostPu</b> = left posterior Pu; <b>PC</b> = posterior commissure; <b>PD</b> = Parkinson disease; <b>Pu</b> = putamen; <b>RantGP</b> = right anterior GP; <b>RantPu</b> = right anterior Pu; <b>RlatSNc</b> = right lateral SNc; <b>RlatSNr</b> = right lateral SNr; <b>RmedSNc</b> = right medial SNc; <b>RmedSNr</b> = right medial SNr; <b>RN</b> = red nucleus; <b>ROI</b> = region of interest; <b>RpostGP</b> = right posterior GP; <b>RpostPu</b> = right posterior Pu; <b>SNc</b> = substantia nigra compacta; <b>SNr</b> = substantia nigra reticulata; <b>TE</b> = echo times; <b>UPDRS</b> = Unified Parkinson9s Disease Rating Scale.
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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) | 0.000 | 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".