Nuclear Medicine

PSMA PET–derived total tumor volume refines outcome prediction for 177Lu-PSMA-617 in mCRPC

In 168 mCRPC patients receiving 177Lu-PSMA-617, baseline PSMA PET/CT–derived total tumor volume (TTV) improved prognostic modeling versus metastasis counts. External validation of prior clinical models yielded C-indices around 0.70 for overall survival, PSA progression-free survival, and PSA50 response. Replacing dichotomized metastasis number with TTV increased the overall survival C-index by 0.04 and strengthened discrimination for PSA outcomes. Higher TTV independently predicted shorter overall survival and PSA progression-free survival and a lower probability of achieving PSA50. Metastasis count lost independent prognostic value, supporting adoption of quantitative PSMA volumetrics for pre-therapy counseling and trial stratification. 1

64Cu-SAR-bisPSMA improves detection and impacts management in low-PSA biochemical recurrence

The prospective Co-PSMA trial enrolled 50 men with post-prostatectomy biochemical recurrence (PSA 0.2–0.75 ng/mL). Per-patient positivity at 24 hours was 78% with 64Cu-SAR-bisPSMA versus 36% with 68Ga-PSMA-11, with 2.6-fold more lesions detected. Reference-standard analysis showed higher true-positive and lower false-negative rates for 64Cu-SAR-bisPSMA than for 68Ga-PSMA-11. Scan findings changed management between the two scans in 44% of patients, indicating substantial real-world impact. These data support 64Cu-SAR-bisPSMA when precise localization at low PSA could redirect salvage radiotherapy or systemic treatment. 2

68Ga-PDL1p PET better predicts lung cancer immunotherapy response than FDG or PD-L1 IHC

In 22 treatment-naïve lung cancer patients, baseline 68Ga-PDL1p PET and FDG PET were performed before systemic therapy. Lesions with high PD-L1 expression showed significantly higher 68Ga-PDL1p uptake, whereas FDG uptake did not differ by PD-L1 status. Among 17 patients receiving chemo-immunotherapy, responders had higher baseline 68Ga-PDL1p uptake, with an AUC of 0.886 for response prediction. Higher baseline 68Ga-PDL1p or FDG uptake associated with longer progression-free survival, while PD-L1 IHC cutoffs failed to stratify outcomes. These results suggest PD-L1–targeted PET may serve as a noninvasive whole-body biomarker for immunotherapy selection and monitoring. 3

Whole-body FDG PET/CT increases source-control procedures for extracardiac endocarditis complications

This prospective registry included 252 patients with possible or definite infective endocarditis; 152 underwent whole-body 18F-FDG PET/CT. The PET/CT group had 57 source-control interventions (SCIs), including 21 directly prompted by PET-identified extracardiac complications, compared with 18 SCIs in controls. Number needed to scan was 8 to generate one additional SCI, indicating meaningful incremental yield. FDG PET/CT was independently associated with more SCIs (adjusted hazard ratio 2.96), but 90-day mortality did not significantly differ. These findings support routine PET/CT to uncover actionable extracardiac foci in infective endocarditis, while mortality benefit remains unproven. 4