Institute of Diagnostic and Interventional Radiology, School of Medicine, Technical University of Munich, Munich, Germany.
Department of Nuclear Medicine, School of Medicine, Technical University of Munich, Munich, Germany.
J Nucl Med. 2021 Aug 1;62(8):1082-1088. doi: 10.2967/jnumed.120.251447. Epub 2020 Dec 4.
Radiohybrid prostate-specific membrane antigen (rhPSMA) ligands are a new class of prostate cancer theranostic agents. F-rhPSMA-7 offers the advantages of F labeling and low urinary excretion compared with Ga-PSMA-11. Here, we compare the frequency of non-tumor-related uptake and tumor positivity with Ga-PSMA-11 and F-rhPSMA-7 in patients with primary or recurrent prostate cancer. This retrospective matched-pair comparison matched 160 F-rhPSMA-7 with 160 Ga-PSMA-11 PET/CT studies for primary staging ( = 33) and biochemical recurrence ( = 127) according to clinical characteristics. Two nuclear medicine physicians reviewed all scans, first identifying all PET-positive lesions and then differentiating lesions suggestive of prostate cancer from those that were benign, on the basis of known pitfalls and ancillary information from CT. For each region, the SUV of the lesion with the highest PSMA ligand uptake was noted. Tumor positivity rates were determined, and SUV was compared separately for each tracer. F-rhPSMA-7 and Ga-PSMA-11 PET revealed 566 and 289 PSMA ligand-positive lesions, respectively. Of these, 379 and 100 lesions, equaling 67.0% and 34.6%, respectively, of all PSMA-positive lesions, were considered benign. The distribution of their etiology was similar (42%, 24%, and 25% with F-rhPSMA-7 vs. 32%, 24%, and 38% with Ga-PSMA-11 for ganglia, bone, and unspecific lymph nodes, respectively). All primary tumors were positive with both agents ( = 33 each), whereas slightly more metastatic lesions were observed with Ga-PSMA-11 in both disease stages (113 for F-rhPSMA-7 and 124 for Ga-PSMA-11). The SUV of F-rhPSMA-7 and Ga-PSMA-11 did not differ ( > 0.05) in local recurrence or primary prostate cancer; however, the tumor-to-bladder ratio was significantly higher with F-rhPSMA-7 (4.9 ± 5.3 vs. 2.2 ± 3.7, = 0.02, for local recurrence; 9.8 ± 9.7 vs. 2.3 ± 2.6, < 0.001, for primary prostate cancer). The tumor positivity rate was consistently high for Ga-PSMA-11 and F-rhPSMA-7. Both tracers revealed a considerable number of areas of uptake that were reliably identified as benign by trained physicians making use of corresponding morphologic imaging and known PSMA pitfalls. These were more frequent with F-rhPSMA-7. However, the matched-pair comparison could have introduced a source of bias. Adequate reader training can allow physicians to differentiate benign uptake from disease and be able to benefit from the logistical and clinical advantages of F-rhPSMA-7.
放射性杂交前列腺特异性膜抗原（rhPSMA）配体是一类新的前列腺癌治疗诊断试剂。与 Ga-PSMA-11 相比，F-rhPSMA-7 具有 F 标记和低尿排泄的优势。在这里，我们比较了 F-rhPSMA-7 和 Ga-PSMA-11 在原发性或复发性前列腺癌患者中的非肿瘤相关摄取和肿瘤阳性率。这项回顾性配对比较根据临床特征，将 160 例原发性分期（ = 33）和生化复发（ = 127）的 F-rhPSMA-7 与 160 例 Ga-PSMA-11 PET/CT 研究进行配对。两位核医学医生首先对所有扫描进行了回顾，根据已知的陷阱和 CT 辅助信息，首先识别出所有 PET 阳性病变，然后区分提示前列腺癌的病变和良性病变。对于每个区域，记录具有最高 PSMA 配体摄取的病变的 SUV。确定肿瘤阳性率，并分别比较每种示踪剂的 SUV。F-rhPSMA-7 和 Ga-PSMA-11 PET 分别显示了 566 和 289 个 PSMA 配体阳性病变。其中，379 个和 100 个病变分别占所有 PSMA 阳性病变的 67.0%和 34.6%，被认为是良性的。它们的病因分布相似（F-rhPSMA-7 为 42%、24%和 25%，Ga-PSMA-11 为 32%、24%和 38%，分别为神经节、骨和非特异性淋巴结）。两种药物均能使所有原发性肿瘤阳性（ = 33 例），但在两个疾病阶段，Ga-PSMA-11 观察到更多的转移性病变（F-rhPSMA-7 为 113 例，Ga-PSMA-11 为 124 例）。F-rhPSMA-7 和 Ga-PSMA-11 的 SUV 在局部复发或原发性前列腺癌中无差异（ > 0.05）；然而，F-rhPSMA-7 的肿瘤-膀胱比显著更高（局部复发时为 4.9 ± 5.3，Ga-PSMA-11 为 2.2 ± 3.7， = 0.02；原发性前列腺癌时为 9.8 ± 9.7，Ga-PSMA-11 为 2.3 ± 2.6， < 0.001）。Ga-PSMA-11 和 F-rhPSMA-7 的肿瘤阳性率均很高。两种示踪剂都显示出相当数量的摄取区域，经过受过训练的医生利用相应的形态学成像和已知的 PSMA 陷阱，这些区域可以可靠地识别为良性。F-rhPSMA-7 中的这些区域更为常见。然而，配对比较可能会引入一个偏倚源。充分的读者培训可以使医生能够从疾病中区分良性摄取，并能够从 F-rhPSMA-7 的后勤和临床优势中受益。
