Comparison of Posttherapy 4- and 24-Hour [<sup>177</sup>Lu]Lu-PSMA SPECT/CT and Pretherapy PSMA PET/CT in Assessment of Disease in Men with Metastatic Castration-Resistant Prostate Cancer
Bibliographic record
Abstract
[177Lu]Lu-prostate-specific membrane antigen (PSMA) is an effective treatment for metastatic castration-resistant prostate cancer (mCRPC). [177Lu]Lu-PSMA SPECT/CT 24 h after injection has shown potential as a response biomarker for [177Lu]Lu-PSMA therapy but is not convenient for patients. This study investigated 4-h [177Lu]Lu-PSMA SPECT/CT as an alternative to 24-h [177Lu]Lu-PSMA SPECT/CT for evaluation of treatment response. Methods: This prospective analysis enrolled 23 patients diagnosed with mCRPC commencing [177Lu]Lu-PSMA-I&T therapy. Two patients were excluded because of incomplete imaging data. Posttherapy SPECT/CT was performed at 4 and 24 h after the first dose and 4 h after the second dose. Baseline [68Ga]Ga-PSMA-11 PET/CT and 4- and 24-h [177Lu]Lu-PSMA SPECT/CT were analyzed both visually and semiquantitatively. Bland–Altman plots assessed agreement of semiquantitative parameters from the 4- and 24-h scans. Quantitative assessment of the change in the total tumor volume (TTV) on the 4-h [177Lu]Lu-PSMA SPECT/CT after the first and second doses was correlated to patient outcomes. Results: All patients had mCRPC previously treated with an androgen receptor pathway inhibitor, and 11 (52%) received prior taxane chemotherapy. Median age was 78 y, and median prostate-specific antigen level was 54 ng/mL. On visual analysis, disease distribution was unchanged among the 3 imaging methods. Eleven patients (52%) had a median of 1 lesion not identified on 4-h [177Lu]Lu-PSMA SPECT/CT compared with 24-h [177Lu]Lu-PSMA SPECT/CT. All missed lesions on the 4-h [177Lu]Lu SPECT/CT were smaller than 2 cm. Mean differences and agreement between 4- and 24-h SPECT/CT quantitative parameters were within acceptable bounds for lesion number, SUVmax, and SUVmean, with higher variation observed for TTV. The change in TTV between dose 1 and 2 [177Lu]Lu-PSMA SPECT/CT predicted prostate-specific antigen progression-free survival. Conclusion: [177Lu]Lu-PSMA SPECT/CT at 4 h after injection appears a promising alternative to 24-h [177Lu]Lu-PSMA SPECT/CT for treatment response assessment, with improved patient convenience.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".