Is early imaging a pitfall? Effect of [⁶⁸Ga]Ga-PSMA PET/CT timing after biopsy on SUVmax and adverse pathology prediction in low-to-intermediate risk prostate cancer.

OBJECTIVE: To investigate the effect of the biopsy-to-imaging interval on intraprostatic maximum standardized uptake value (SUVmax) and adverse pathology (AP) prediction in patients with low-to-intermediate risk prostate cancer (PCa) undergoing [⁶⁸Ga]Ga-PSMA PET/CT. METHODS: In this retrospective study, 120 patients with ISUP grade 1-2 PCa who underwent [⁶⁸Ga]Ga-PSMA PET/CT followed by radical prostatectomy between February 2022 and June 2025 were analyzed. Patients were classified into an early (≤ 6 weeks, n = 68) and a late group (> 6 weeks, n = 52) by the biopsy-to-PET/CT interval. AP was defined as ISUP grade ≥ 3 or extracapsular disease on the surgical specimen. Predictors of AP were assessed by binary logistic regression. RESULTS: AP was detected in 47 patients (39.2%). The median biopsy-to-PET/CT interval was 39 days (range 10-198). Intraprostatic SUVmax was significantly higher and more variable in the early than the late group (5.9 ± 3.4 vs. 4.7 ± 2.2; p = 0.014; Levene p = 0.026). On univariable analysis, SUVmax (OR 1.19 per unit, 95% CI 1.04-1.36; p = 0.010), PSA density (OR 1.53 per 0.1 ng/mL/cc; p = 0.018), PI-RADS (OR 1.69 per point; p = 0.009) and non-fulfillment of NCCN active-surveillance (AS) criteria (OR 2.59; p = 0.013) were associated with AP, but none of these variables retained significance in the multivariable model, in which SUVmax showed the strongest trend (OR 1.13; p = 0.080). In subgroup analysis, SUVmax significantly predicted AP in the late group (OR 1.36 per unit; p = 0.038) but not in the early group (OR 1.13 per unit; p = 0.099) suggesting that delayed imaging may improve the prediction of AP. CONCLUSION: Biopsy-to-PET/CT timing may influence the distribution and predictive performance of SUVmax in low-to-intermediate-risk prostate cancer. The association between SUVmax and adverse pathology was evident only beyond 6 weeks after biopsy, suggesting that delayed imaging may improve the clinical interpretability of SUVmax, although prospective validation is warranted.