This analysis aimed to identify clinical factors associated with positivity on repeat ⁶⁸Ga-PSMA-11 PET/CT after a negative scan in patients with recurrent prostate cancer (PCa) under observation. Methods: This single-center, retrospective analysis included patients who underwent at least 2 ⁶⁸Ga-PSMA-11 PET/CT scans (PET1 and PET2) at UCLA between October 2016 and June 2021 for recurrent PCa with negative PET1 and no PCa-related treatments between the 2 scans. Using Prostate Cancer Molecular Imaging Standardized Evaluation criteria to define negative and positive scans, the final cohort was divided into PET2-negative (PET2-Neg) and PET2-positive (PET2-Pos). The same PET1 was used twice in the more than 2 PET cases with inclusion criteria fulfilled. Patient characteristics and clinical parameters were compared between the 2 cohorts using Mann–Whitney U test and Fisher exact test. Areas under the curve (AUCs) of the receiver operating characteristic and the Youden index were computed to determine the discrimination ability of statistically significant factors and specific cut points that maximized sensitivity and specificity, respectively. Results: The final analysis included 83 sets of 2 PET/CT scans from 70 patients. Thirty-nine of 83 (47%) sets were PET2-Neg, and 44 of 83 (53%) sets were PET2-Pos. Prostate-specific antigen (PSA) increased from PET1 to PET2 for all 83 (100%) sets of scans. Median PSA at PET1 was 0.4 ng/mL (interquartile range, 0.2–1.0) and at PET2 was 1.6 ng/mL (interquartile range, 0.9–3.8). We found higher serum PSA at PET2 (median, 1.8 vs. 1.1 ng/mL; P = 0.015), absolute PSA difference (median, 1.4 vs. 0.7 ng/mL; P = 0.006), percentage of PSA change (median, +270.4% vs. +150.0%: P = 0.031), and median PSA velocity (0.044 vs. 0.017 ng/mL/wk, P = 0.002) and shorter PSA doubling time (DT; median, 5.1 vs. 8.3 mo; P = 0.006) in the PET2-Pos cohort than in the PET2-Neg cohort. Receiver operating characteristic curves showed cutoffs for PSA at PET2 of 4.80 ng/mL (sensitivity, 34%; specificity, 92%; AUC, 0.66), absolute PSA difference of 0.95 ng/mL (sensitivity, 62%; specificity, 71%; AUC, 0.68), percentage of PSA change of a positive 289.50% (sensitivity, 48%; specificity, 82%; AUC, 0.64), PSA velocity of 0.033 ng/mL/wk (sensitivity, 57%; specificity, 80%; AUC, 0.70), and PSA DT of 7.91 mo (sensitivity, 71%; specificity, 62%; AUC, 0.67). Conclusion: Patients with recurrent PCa under observation after a negative ⁶⁸Ga-PSMA-11 PET/CT scan with markedly elevated serum PSA levels and shorter PSA DT are more likely to have positive findings on repeat ⁶⁸Ga-PSMA-11 PET/CT.

该分析旨在确定与观察中的复发性前列腺癌 (PCa) 患者扫描阴性后重复⁶⁸ Ga-PSMA-11 PET/CT 呈阳性相关的临床因素。方法：这项单中心回顾性分析纳入了 2016 年 10 月至 2021 年 6 月期间在 UCLA 接受至少 2 ⁶⁸ Ga-PSMA-11 PET/CT 扫描（PET1 和 PET2）的患者，以发现 PET1 阴性且无 PCa 相关的复发性 PCa。两次扫描之间的治疗。使用前列腺癌分子影像标准化评估标准来定义阴性和阳性扫描，最终队列分为 PET2 阴性 (PET2-Neg) 和 PET2 阳性 (PET2-Pos)。在满足纳入标准的 2 例以上 PET 病例中，相同的 PET1 被使用了两次。使用 Mann-Whitney U检验和 Fisher 精确检验比较 2 个队列之间的患者特征和临床参数。计算受试者工作特征的曲线下面积 (AUC) 和约登指数，以确定统计显着因素的辨别能力以及分别最大化敏感性和特异性的特定切点。结果：最终分析包括 70 名患者的 83 组 2 次 PET/CT 扫描。 83 组中的 39 组 (47%) 为 PET2-Neg，83 组中的 44 组 (53%) 为 PET2-Pos。在所有 83 组 (100%) 扫描中，前列腺特异性抗原 (PSA) 从 PET1 增加到 PET2。 PET1 的中位 PSA 为 0.4 ng/mL（四分位距，0.2-1.0），PET2 的中位 PSA 为 1.6 ng/mL（四分位距，0.9-3.8）。我们发现 PET2 时的血清 PSA 较高（中位数为 1.8 与 1.1 ng/mL； P = 0.015），绝对 PSA 差异（中位数为 1.4 与 0.7 ng/mL； P = 0）。006)、PSA 变化百分比（中位，+270.4% 与 +150.0%： P = 0.031）、中位 PSA 速度（0.044 与 0.017 ng/mL/wk， P = 0.002）和更短的 PSA 倍增时间 (DT ；中位数为 5.1 个月 vs. 8.3 个月； P = 0.006) PET2-Pos 队列比 PET2-Neg 队列。受试者工作特征曲线显示 PET2 时 PSA 的截止值为 4.80 ng/mL（敏感性，34%；特异性，92%；AUC，0.66），绝对 PSA 差异为 0.95 ng/mL（敏感性，62%；特异性，71%；AUC，0.66）。 AUC，0.68），PSA 阳性变化百分比 289.50%（敏感性，48%；特异性，82%；AUC，0.64），PSA 速度 0.033 ng/mL/wk（敏感性，57%；特异性，80%；AUC，0.64）。 AUC，0.70），PSA DT 为 7.91 mo（敏感性，71%；特异性，62%；AUC，0.67）。结论：在⁶⁸ Ga-PSMA-11 PET/CT 扫描阴性后观察的复发性 PCa 患者，血清 PSA 水平显着升高且 PSA DT 较短，更有可能在重复⁶⁸ Ga-PSMA-11 PET/CT 中出现阳性结果。