Clinical value of whole body 18F-FDG PET/CT imaging in patients with cutaneous melanoma: A multi-center cohort study
Bibliographic record
Abstract
BACKGROUND: F-FDG-PET/CT is a valuable tool in the staging and surveillance of cutaneous melanoma; however, recent studies prompt debate on the clinical significance of imaging patients below the lesser trochanter. This study explored two research questions. In patients with a known primary cutaneous melanoma within the standard field of view (SFOV, between the orbits and lesser trochanter), what is the prevalence of metastasis to sites solely within the lower extremities? and, In patients with a known primary cutaneous melanoma within the SFOV what demographic and clinical factors are associated with sole metastasis to the lower extremities? METHODS: F-FDG-PET/CT (from vertex to toes) for staging and/or follow-up of cutaneous melanoma. Data was collected at three primary healthcare centers in Canada (Nova Scotia, Alberta, and British Columbia). Inclusion criteria were patients >18 years of age, confirmed primary cutaneous melanoma, and a known location of the primary within the SFOV. Patients with primary cutaneous melanoma lesions in lower extremities and previous other cancers were excluded. To determine the prevalence of lesions located below the lesser trochanter, the proportion of such lesions were computed, and 95% confidence intervals ensured a precise estimation of the proportion. RESULTS: 2512 patient charts were reviewed with 619 meeting the inclusion criteria, 298 of these were females. Six percent had metastases in both the lower extremities and sites within the SFOV. The number of subjects who had no metastasis within their SFOV was 361 (58.3%). The number of subjects who presented with confirmed metastasis in the lower extremities without concurrent metastasis in the SFOV region was one (0.58%). Despite a large initial study sample, the number of patients with metastasis in the lower extremities was insufficient to allow correlation of factors associated with risk of spread to the lower extremities. CONCLUSION: F-FDG-PET/CT provided additional, relevant clinical data in a sole patient. This finding supports prior research suggesting the prevalence is rare. Future studies should seek to define demographic and clinical factors that predict such rare occurrences, where follow up would be warranted. This study highlights feasibility challenges associated with such investigation.
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How this classification was reachedexpand
Direct model labels (unvalidated)
Per-model category and study-design labels from the labeling rounds. They are machine output, unvalidated, and the disagreement between models ships as data. No study design here is MEDLINE-validated yet.
| Model arm | Categories | Study design | Confidence |
|---|---|---|---|
| gemma | no category Domain: not available · Genre: Empirical About the Canadian research system: no · About a Canadian topic: no | Observational | low |
| gpt | no category Domain: not available · Genre: Empirical About the Canadian research system: no · About a Canadian topic: no | Observational | high |
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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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, unvalidatedLabeled directly by 2 models reading the full record.
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".