Longitudinal Voxel-Based Analysis of Brain Atrophy over 6 and 12 Months in CBD and PSP from Two Multicenter Studies (S15.007)
Bibliographic record
Abstract
OBJECTIVE: To determine rates of regional brain atrophy in progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) over 6 months and 1 year. BACKGROUND: Previous cross-sectional volumetric MRI studies of PSP have demonstrated profound brainstem and frontal cortical atrophy. CBD shows more widespread dorsal frontoparietal atrophy with less brainstem involvement. The regional patterns of volume loss over time in these populations have not yet been fully examined, particularly over 6 months. DESIGN/METHODS: T1-weighted structural MR images from PSP (total n=48), CBD (total n=27), and normal control (NC) (total n=47) groups were acquired at 3T and processed using a novel longitudinal pipeline implemented in SPM12 to determine changes in cortical and subcortical volumes. Participants were drawn from the 4 Repeat Tauopathy Neuroimaging Initiative (4RTNI) multicenter study, and results were compared to PSP data from the AL-108-231 multicenter trial (total PSP n=226; NC n=102). Reported changes were significant as compared to NC (p<0.05, FWE corrected). RESULTS: Over 6 months, PSP regional brain volume loss was greatest in midbrain, whereas CBD had more prominent volume loss in superior frontoparietal white matter. Over 1 year, PSP showed greatest volume loss in pons, midbrain, and superior cerebellar peduncle, whereas CBD showed modest brainstem atrophy with more pronounced frontoparietal white and gray matter changes. An independent dataset, the AL-108-231 PSP trial cohort, showed nearly identical patterns and magnitudes of atrophy to 4RTNI over 1 year. CONCLUSIONS: Progressive brain atrophy is measureable in CBD and PSP over 6 months and 1 year and resembles atrophy patterns seen in cross-sectional studies. The reproducibility of longitudinal brain atrophy measurements from two independent PSP data sets and their sensitivity to change over 6 months support their utility as outcome measures in clinical trials of tau-directed therapies. Study Supported by: R01AG038791 and Tau Consortium
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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 | 0.003 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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".