[18F]F-Prostate-specific Membrane Antigen-1007 and [68Ga] Ga-Prostate-specific Membrane Antigen-11 Positron Emission Tomography in Prostate Cancer: Do Standardized Uptake Value Correlations Dictate Choice?

Objective: To characterize correlations (ρ) between imaging and patient-related parameters in [ 18 F] F-prostate-specific membrane antigen (PSMA)-1007 and [ 68 Ga] Ga-PSMA-11 positron emission tomography-computed tomography (PET-CT) and to determine whether observed differences influence clinical tracer interchangeability. Materials and Methods: Two retrospective PET-CT cohorts from a single-center database were analyzed, comprising patients imaged for suspected prostate cancer with either tracer. Spearman rank intra-tracer correlation coefficients were calculated between weight, body surface area (BSA), lean body mass (LBM), lesion maximum standardized uptake value (SUVmax) (T), liver mean SUV (SUVmean) (B), tumor-to-background ratio (T/B), and metabolic tumor volume. Inter-tracer comparisons were performed using Fisher-transformed paired correlation coefficients, with Bonferroni correction to control type I error. Results: Mann–Whitney testing demonstrated no significant differences in weight ( P = 0.50), BSA ( P = 0.50), or LBM ( P = 0.47) distributions between cohorts. Intra-tracer heatmaps showed broadly similar correlation patterns and significance distributions across tracers. Inter-tracer analysis identified significant differences in correlations between liver SUVmean with weight (ρ = 0.43, P = 0.0001), BSA (ρ = 0.29, P = 0.0001), and LBM (ρ = 0.29, P = 0.0001). These differences were nullified when standard weight-based liver SUVmean normalization for [ 68 Ga] Ga-PSMA-11 was replaced with LBM normalization (weight: ρ = −0.01, P = 0.96; BSA: ρ = −0.04, P = 0.75; LBM: ρ = −0.04, P = 0.75) or BSA normalization (weight: ρ = −0.09, P = 0.49; BSA: ρ = −0.12, P = 0.36; LBM: ρ = −0.12, P = 0.36). Conclusion: Correlation structures for the two tracers were broadly comparable across most imaging and demographic variables. Observed differences in liver SUVmean correlations with body habitus parameters were mitigated by BSA or LBM normalization. These findings support clinical tracer interchangeability. However, full characterization is recommended when alternative SUV normalizations are applied or when liver SUVmean is used as background reference tissue in tumor-to-background trial selection criteria.