Despite a high detection rate of ⁶⁸Ga-prostate-specific membrane antigen (PSMA) PET/CT in biochemical recurrence (BCR) of prostate cancer, a significant proportion of men have negative ⁶⁸Ga-PSMA-11 PET/CT results. Gastrin-releasing peptide receptor, targeted by the copper-chelated bombesin analog ⁶⁴Cu-sarcophagine-bombesin (SAR-BBN) PET/CT, is also overexpressed in prostate cancer. In this prospective imaging study, we investigate the detection rate of ⁶⁴Cu-SAR-BBN PET/CT in patients with BCR and negative or equivocal ⁶⁸Ga-PSMA-11 PET/CT results. Methods: Men with confirmed adenocarcinoma of the prostate, prior definitive therapy, and BCR (defined as a prostate-specific antigen [PSA] level > 0.2 ng/mL) with negative or equivocal ⁶⁸Ga-PSMA-11 PET/CT results within 3 mo were eligible for enrollment. ⁶⁴Cu-SAR-BBN PET/CT scans were acquired at 1 and 3 h after administration of 200 MBq of ⁶⁴Cu-SAR-BBN, with further delayed imaging undertaken optionally at 24 h. PSA (ng/mL) was determined at baseline. All PET (PSMA and bombesin) scans were assessed visually. Images were read with masking of the clinical results by 2 experienced nuclear medicine specialists, with a third reader in cases of discordance. Accuracy was defined using a standard of truth that included biopsy confirmation, confirmatory imaging, or response to targeted treatment. Results: Twenty-five patients were enrolled. Prior definitive therapy was radical prostatectomy (n = 24, 96%) or radiotherapy (n = 1, 4%). The median time since definitive therapy was 7 y (interquartile range [IQR], 4–11 y), and the Gleason score was 7 or less (n = 15, 60%), 8 (n = 3, 12%), or 9 (n = 7, 28%). The median PSA was 0.69 ng/mL (IQR, 0.28–2.45 ng/mL). Baseline PSMA PET scans were negative in 19 patients (76%) and equivocal in 6 (24%). ⁶⁴Cu-SAR-BBN PET–avid disease was identified in 44% (11/25): 12% (3/25) with local recurrence, 20% (5/25) with pelvic node metastases, and 12% (3/25) with distant metastases. The κ-score between readers was 0.49 (95% CI, 0.16–0.82). Patients were followed up for a median of 10 mo (IQR, 9–12 mo). Bombesin PET/CT results were true-positive in 5 of 25 patients (20%), false-positive in 2 of 25 (8%), false-negative in 7 of 25 (28%), and unverified in 11 of 25 (44%). Conclusion: ⁶⁴Cu-SAR-BBN PET/CT demonstrated sites of disease recurrence in 44% of BCR cases with negative or equivocal ⁶⁸Ga-PSMA-11 PET/CT results. Further evaluation to confirm diagnostic benefit is warranted.

尽管⁶⁸ Ga-前列腺特异性膜抗原 (PSMA) PET/CT 在前列腺癌生化复发 (BCR) 中的检出率很高，但很大一部分男性⁶⁸ Ga-PSMA-11 PET/CT 结果呈阴性。铜螯合铃蟾肽类似物⁶⁴ Cu-肌噬素铃蟾肽 (SAR-BBN) PET/CT 靶向的胃泌素释放肽受体也在前列腺癌中过度表达。在这项前瞻性影像学研究中，我们调查了 BCR 和⁶⁸ Ga-PSMA-11 PET/CT 结果阴性或可疑的患者中⁶⁴ Cu-SAR-BBN PET/CT 的检出率。方法：患有确诊前列腺癌、既往接受过明确治疗且 BCR（定义为前列腺特异性抗原 [PSA] 水平 > 0.2 ng/mL）且⁶⁸ Ga-PSMA-11 PET/CT 结果呈阴性或可疑的男性3个月有资格入学。在施用 200 MBq ⁶⁴ Cu-SAR-BBN 后 1 小时和 3 小时获得⁶⁴ Cu-SAR-BBN PET/CT 扫描，并可选择在 24 小时进行进一步延迟成像。 PSA (ng/mL) 在基线时测定。所有 PET（PSMA 和蛙皮素）扫描均通过目视评估。图像由 2 名经验丰富的核医学专家在屏蔽临床结果的情况下读取图像，如果不一致，则由第三位读取器读取。准确性是使用真实标准来定义的，包括活检确认、确认性成像或对靶向治疗的反应。结果： 25 名患者入组。先前的确定性治疗是根治性前列腺切除术 ( n = 24, 96%) 或放射治疗 ( n = 1, 4%)。 自确定性治疗以来的中位时间为 7 年（四分位数间距 [IQR]，4-11 年），格里森评分为 7 或更低 ( n = 15, 60%)、8 ( n = 3, 12%)，或9（ n = 7，28%）。 PSA 中位数为 0.69 ng/mL（IQR，0.28–2.45 ng/mL）。 19 名患者 (76%) 的基线 PSMA PET 扫描结果为阴性，6 名患者 (24%) 的基线 PSMA PET 扫描结果可疑。 ⁶⁴ 44% (11/25) 发现了 Cu-SAR-BBN PET 热疾病：12% (3/25) 出现局部复发，20% (5/25) 出现盆腔淋巴结转移，12% (3/ 25）有远处转移。读者之间的 κ 分数为 0.49（95% CI，0.16-0.82）。患者的随访时间中位数为 10 个月（IQR，9-12 个月）。铃蟾肽 PET/CT 结果在 25 名患者中 5 名 (20%) 为真阳性，在 25 名患者中 2 名 (8%) 为假阳性，在 25 名患者中 7 名 (28%) 为假阴性，在 25 名患者中 11 名未经验证（ 44%）。结论： ⁶⁴ Cu-SAR-BBN PET/CT 显示 44% ⁶⁸ Ga-PSMA-11 PET/CT 结果阴性或模棱两可的 BCR 病例中有疾病复发部位。需要进一步评估以确认诊断益处。