⁶⁸Ga-RM2 targets gastrin-releasing peptide receptors (GRPRs), which are overexpressed in prostate cancer (PC). Here, we compared preoperative ⁶⁸Ga-RM2 PET to postsurgery histopathology in patients with newly diagnosed intermediate- or high-risk PC. Methods: Forty-one men, 64.0 ± 6.7 y old, were prospectively enrolled. PET images were acquired 42–72 min (median ± SD, 52.5 ± 6.5 min) after injection of 118.4–247.9 MBq (median ± SD, 138.0 ± 22.2 MBq) of ⁶⁸Ga-RM2. PET findings were compared with preoperative multiparametric MRI (mpMRI) (n = 36) and ⁶⁸Ga-PSMA11 PET (n = 17) and correlated to postprostatectomy whole-mount histopathology (n = 32) and time to biochemical recurrence. Nine participants decided to undergo radiation therapy after study enrollment. Results: All participants had intermediate- (n = 17) or high-risk (n = 24) PC and were scheduled for prostatectomy. Prostate-specific antigen was 8.8 ± 77.4 (range, 2.5–504) and 7.6 ± 5.3 ng/mL (range, 2.5–28.0 ng/mL) when participants who ultimately underwent radiation treatment were excluded. Preoperative ⁶⁸Ga-RM2 PET identified 70 intraprostatic foci of uptake in 40 of 41 patients. Postprostatectomy histopathology was available in 32 patients in which ⁶⁸Ga-RM2 PET identified 50 of 54 intraprostatic lesions (detection rate = 93%). ⁶⁸Ga-RM2 uptake was recorded in 19 nonenlarged pelvic lymph nodes in 6 patients. Pathology confirmed lymph node metastases in 16 lesions, and follow-up imaging confirmed nodal metastases in 2 lesions. ⁶⁸Ga-PSMA11 and ⁶⁸Ga-RM2 PET identified 27 and 26 intraprostatic lesions, respectively, and 5 pelvic lymph nodes each in 17 patients. Concordance between ⁶⁸Ga-RM2 and ⁶⁸Ga-PSMA11 PET was found in 18 prostatic lesions in 11 patients and 4 lymph nodes in 2 patients. Noncongruent findings were observed in 6 patients (intraprostatic lesions in 4 patients and nodal lesions in 2 patients). Sensitivity and accuracy rates for ⁶⁸Ga-RM2 and ⁶⁸Ga-PSMA11 (98% and 89% for ⁶⁸Ga-RM2 and 95% and 89% for ⁶⁸Ga-PSMA11) were higher than those for mpMRI (77% and 77%, respectively). Specificity was highest for mpMRI with 75% followed by ⁶⁸Ga-PSMA11 (67%) and ⁶⁸Ga-RM2 (65%). Conclusion: ⁶⁸Ga-RM2 PET accurately detects intermediate- and high-risk primary PC, with a detection rate of 93%. In addition, ⁶⁸Ga-RM2 PET showed significantly higher specificity and accuracy than mpMRI and a performance similar to ⁶⁸Ga-PSMA11 PET. These findings need to be confirmed in larger studies to identify which patients will benefit from one or the other or both radiopharmaceuticals.

⁶⁸ Ga-RM2 靶向胃泌素释放肽受体 (GRPR)，该受体在前列腺癌 (PC) 中过度表达。在这里，我们将术前⁶⁸ Ga-RM2 PET 与新诊断的中高风险 PC 患者的术后组织病理学进行了比较。方法： 41 名 64.0 ± 6.7 岁的男性被前瞻性纳入。在注射 118.4–247.9 MBq（中值 ± SD，138.0 ± 22.2 MBq）的⁶⁸ Ga-RM2 后 42–72 分钟（中值 ± SD，52.5 ± 6.5 分钟）获取 PET 图像。PET 结果与术前多参数 MRI (mpMRI)（n = 36）和⁶⁸ Ga-PSMA11 PET（n = 17）进行了比较，并与前列腺切除术后整体组织病理学相关（n= 32) 和生化复发时间。九名参与者决定在研究登记后接受放射治疗。结果：所有参与者都有中度风险（ n = 17）或高风险（n = 24）PC，并计划进行前列腺切除术。当最终接受放射治疗的参与者被排除在外时，前列腺特异性抗原为 8.8 ± 77.4（范围，2.5-504）和 7.6 ± 5.3 ng/mL（范围，2.5-28.0 ng/mL）。术前⁶⁸ Ga-RM2 PET 在 41 名患者中的 40 名中确定了 70 个前列腺内摄取灶。前列腺切除术后组织病理学可用于 32 名患者，其中⁶⁸ Ga-RM2 PET 识别出 54 个前列腺内病变中的 50 个（检出率 = 93%）。⁶⁸在 6 名患者的 19 个非肿大盆腔淋巴结中记录到 Ga-RM2 摄取。病理证实淋巴结转移16处，影像学随访证实淋巴结转移2处。⁶⁸ Ga-PSMA11 和⁶⁸ Ga-RM2 PET 分别确定了 27 和 26 个前列腺内病变，17 名患者各有 5 个盆腔淋巴结。在 11 名患者的 18 个前列腺病变和 2 名患者的 4 个淋巴结中发现⁶⁸ Ga-RM2 和⁶⁸ Ga-PSMA11 PET之间的一致性。在 6 名患者中观察到不一致的发现（4 名患者的前列腺内病变和 2 名患者的淋巴结病变）。⁶⁸ Ga-RM2 和⁶⁸ Ga-PSMA11 的灵敏度和准确率（68 为⁹⁸ % 和 89%^{Ga-RM2 和68} Ga-PSMA11的 95% 和 89% ）高于 mpMRI（分别为 77% 和 77%）。mpMRI 的特异性最高，为 75%，其次是⁶⁸ Ga-PSMA11 (67%) 和⁶⁸ Ga-RM2 (65%)。结论： ^68Ga -RM2 PET准确检测中高危原发性PC，检出率为93%。此外，⁶⁸ Ga-RM2 PET 显示出明显高于 mpMRI 的特异性和准确性，并且性能与⁶⁸ Ga-PSMA11 PET 相似。这些发现需要在更大规模的研究中得到证实，以确定哪些患者将从一种或另一种或两种放射性药物中受益。