Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Stanford University, Stanford, California.
Department of Urology, Stanford University, Stanford, California.
J Nucl Med. 2022 Dec;63(12):1829-1835. doi: 10.2967/jnumed.122.263971. Epub 2022 May 12.
Ga-RM2 targets gastrin-releasing peptide receptors (GRPRs), which are overexpressed in prostate cancer (PC). Here, we compared preoperative Ga-RM2 PET to postsurgery histopathology in patients with newly diagnosed intermediate- or high-risk PC. 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 Ga-RM2. PET findings were compared with preoperative multiparametric MRI (mpMRI) ( = 36) and Ga-PSMA11 PET ( = 17) and correlated to postprostatectomy whole-mount histopathology ( = 32) and time to biochemical recurrence. Nine participants decided to undergo radiation therapy after study enrollment. All participants had intermediate- ( = 17) or high-risk ( = 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 Ga-RM2 PET identified 70 intraprostatic foci of uptake in 40 of 41 patients. Postprostatectomy histopathology was available in 32 patients in which Ga-RM2 PET identified 50 of 54 intraprostatic lesions (detection rate = 93%). Ga-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. Ga-PSMA11 and Ga-RM2 PET identified 27 and 26 intraprostatic lesions, respectively, and 5 pelvic lymph nodes each in 17 patients. Concordance between Ga-RM2 and Ga-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 Ga-RM2 and Ga-PSMA11 (98% and 89% for Ga-RM2 and 95% and 89% for Ga-PSMA11) were higher than those for mpMRI (77% and 77%, respectively). Specificity was highest for mpMRI with 75% followed by Ga-PSMA11 (67%) and Ga-RM2 (65%). Ga-RM2 PET accurately detects intermediate- and high-risk primary PC, with a detection rate of 93%. In addition, Ga-RM2 PET showed significantly higher specificity and accuracy than mpMRI and a performance similar to Ga-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.
Ga-RM2 靶向胃泌素释放肽受体（GRPRs），其在前列腺癌（PC）中过度表达。在这里，我们比较了新诊断为中高危 PC 患者的术前 Ga-RM2 PET 与术后组织病理学。41 名男性，年龄 64.0 ± 6.7 岁，前瞻性入组。在注射 118.4-247.9 MBq（中位数 ± SD，138.0 ± 22.2 MBq）的 Ga-RM2 后 42-72 分钟（中位数 ± SD，52.5 ± 6.5 分钟）采集 PET 图像。将 PET 结果与术前多参数 MRI（mpMRI）（=36）和 Ga-PSMA11 PET（=17）进行比较，并与前列腺切除术后全组织病理学（=32）和生化复发时间相关。9 名参与者在研究入组后决定接受放射治疗。所有参与者均患有中危（=17）或高危（=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 ± 5.3ng/mL（范围 2.5-28.0ng/mL）。术前 Ga-RM2 PET 在 41 名患者中的 40 名患者中识别出 70 个前列腺内摄取灶。在 32 名可获得前列腺切除术后组织病理学的患者中，Ga-RM2 PET 识别出 54 个前列腺内病变中的 50 个（检出率=93%）。Ga-RM2 摄取在 6 名患者的 19 个非增大的盆腔淋巴结中记录到。病理学证实 16 个病变存在淋巴结转移，随访影像学证实 2 个病变存在淋巴结转移。Ga-PSMA11 和 Ga-RM2 PET 在 17 名患者中分别识别出 27 个和 26 个前列腺内病变，在 17 名患者中各识别出 5 个盆腔淋巴结。在 11 名患者中的 18 个前列腺病变和 2 名患者中的 4 个淋巴结中发现 Ga-RM2 和 Ga-PSMA11 PET 之间存在一致性。在 6 名患者（4 名患者的前列腺病变和 2 名患者的淋巴结病变）中观察到不一致的结果。Ga-RM2 和 Ga-PSMA11 的敏感性和准确性（Ga-RM2 为 98%和 89%，Ga-PSMA11 为 95%和 89%）均高于 mpMRI（分别为 77%和 77%）。mpMRI 的特异性最高，为 75%，其次是 Ga-PSMA11（67%）和 Ga-RM2（65%）。Ga-RM2 PET 准确检测中高危原发性 PC，检出率为 93%。此外，Ga-RM2 PET 的特异性和准确性均明显高于 mpMRI，与 Ga-PSMA11 PET 的性能相似。这些发现需要在更大的研究中得到证实，以确定哪些患者将受益于一种或另一种或两者放射性药物。
