¹⁸F-rhPSMA-7.3, the lead compound of a new class of radiohybrid prostate-specific membrane antigen (rhPSMA) ligand, is currently in phase III trials for prostate cancer (PCa) imaging. Here, we describe our experience in primary PCa staging. Methods: We retrospectively identified 279 patients with primary PCa who underwent ¹⁸F-rhPSMA-7.3 PET/CT (staging cohort). A subset of patients (83/279) subsequently underwent prostatectomy with lymph node (LN) dissection without prior treatment (efficacy cohort). The distribution of tumor lesions was determined for the staging cohort and stratified by National Comprehensive Cancer Network risk score. Involvement of pelvic LNs was assessed retrospectively by 3 masked independent central readers, and a majority rule was used for analysis. Standard surgical fields were rated on a 5-point scale independently for PET and for morphologic imaging. Results were compared with histopathologic findings on a patient, right-vs.-left, and template basis. Results: For the staging cohort, ¹⁸F-rhPSMA-7.3 PET was positive in 275 of 279 (98.6%), 106 of 279 (38.0%), 46 of 279 (16.5%), 65 of 279 (23.3%), and 5 of 279 (1.8%) patients for local, pelvic nodal, extrapelvic nodal, metastatic bone, and visceral metastatic disease, respectively. In the efficacy cohort, LN metastases were present in 24 of 83 patients (29%) and were located in 48 of 420 (11%) resected templates and in 33 of 166 (19.9%) hemipelvic templates in histopathology. The majority vote results showed that patient-level sensitivity, specificity, and accuracy for pelvic nodal metastases were 66.7% (95% CI, 44.7%–83.6%), 96.6% (95% CI, 87.3%–99.4%), and 88.0% (95% CI, 78.5%–93.8%), respectively, for ¹⁸F-rhPSMA-7.3 PET and 37.5% (95% CI, 19.6%–59.2%), 91.5% (95% CI, 80.6%–96.8%), and 75.9% (95% CI, 65.0%–84.3%), respectively, for morphologic imaging. ¹⁸F-rhPSMA-7.3 showed higher interobserver agreement than morphologic imaging (patient-level Fleiss = 0.54 [95% CI, 0.47–0.62] vs. 0.24 [95% CI, 0.17–0.31]). A mean SUV ratio of 6.6 (95% CI, 5.2–8.1) documented a high image contrast between local tumors and adjacent low urinary tracer retention. Conclusion: ¹⁸F-rhPSMA-7.3 PET offers diagnostic performance superior to morphologic imaging for primary N-staging of newly diagnosed PCa, shows lower interreader variation, and offers good distinction between primary-tumor activity and bladder background activity. With increasing National Comprehensive Cancer Network risk group, an increasing frequency of extraprostatic tumor lesions was observed.

¹⁸ F-rhPSMA-7.3 是一类新型放射性混合前列腺特异性膜抗原 (rhPSMA) 配体的先导化合物，目前正处于前列腺癌 (PCa) 成像的 III 期试验中。在这里，我们描述了我们在初级 PCa 分期方面的经验。方法：我们回顾性确定了 279 名原发性 PCa 患者，他们接受了¹⁸F-rhPSMA-7.3 PET/CT（分期队列）。一部分患者 (83/279) 随后在没有事先治疗的情况下接受了前列腺切除术和淋巴结 (LN) 清扫术（疗效队列）。肿瘤病变的分布由分期队列确定，并通过国家综合癌症网络风险评分进行分层。盆腔淋巴结受累情况由 3 名蒙面独立中心读者回顾性评估，并使用多数规则进行分析。对于 PET 和形态学成像，标准手术野以 5 分制独立评分。将结果与患者、右对左和模板的组织病理学结果进行比较。结果：对于分期队列，¹⁸F-rhPSMA-7.3 PET 在 279 名患者中的 275 名（98.6%）、279 名中的 106 名（38.0%）、279 名中的 46 名（16.5%）、279 名中的 65 名（23.3%）和 279 名中的 5 名（1.8%）患者中呈阳性分别用于局部、盆腔淋巴结、盆外淋巴结、转移性骨和内脏转移性疾病。在疗效队列中，83 名患者中有 24 名 (29%) 存在 LN 转移，并且在组织病理学中位于 420 个切除模板中的 48 个 (11%) 和 166 个半盆腔模板中的 33 个 (19.9%)。多数投票结果显示，盆腔淋巴结转移的患者水平敏感性、特异性和准确性分别为 66.7%（95% CI，44.7%–83.6%）、96.6%（95% CI，87.3%–99.4%）和 88.0 %（95% CI，78.5%–93.8%），分别为¹⁸F-rhPSMA-7.3 PET 和 37.5%（95% CI，19.6%–59.2%）、91.5%（95% CI，80.6%–96.8%）和 75.9%（95% CI，65.0%–84.3%），分别用于形态学成像。¹⁸ F-rhPSMA-7.3 显示出比形态成像更高的观察者间一致性（患者水平 Fleiss = 0.54 [95% CI, 0.47–0.62] vs. 0.24 [95% CI, 0.17–0.31]）。平均 SUV 比率为 6.6（95% CI，5.2-8.1），记录了局部肿瘤和相邻低尿示踪剂潴留之间的高图像对比度。结论： ¹⁸F-rhPSMA-7.3 PET 对新诊断的 PCa 的初级 N 分期提供了优于形态学成像的诊断性能，显示出较低的阅读者间变异，并在原发肿瘤活动和膀胱背景活动之间提供了良好的区分。随着国家综合癌症网络风险组的增加，观察到前列腺外肿瘤病变的频率增加。