Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine.
Department of Urology, Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria.
Curr Opin Urol. 2023 May 1;33(3):206-210. doi: 10.1097/MOU.0000000000001090. Epub 2023 Mar 6.
The aim of this study was to summarize the available evidence on different PET imaging modalities for the staging of patients diagnosed with bladder cancer (BCa). We further discuss the use of PET/computed tomography (CT) and PET/MRI with different radiopharmaceuticals to characterize tumour biology for treatment guidance.
Available evidence supports the benefits of PET/CT in BCa staging due to its higher accuracy in the detection of nodal metastases compared with CT alone. The use of PET/MRI is of major future interest due to the higher soft tissue contrast of MRI, which might enable the early detection of the tumour in the bladder. For the time being, the sensitivity of PET/MRI is still too low, when it comes to the diagnosis of early-stage BCa. This is mainly due to the renal excretion of the commonly used [ 18 F]FDG PET tracer, wherefore small lesions in the wall of the bladder can be missed. Novel studies using PET radiopharmaceuticals to target immune checkpoints or other immune cell targets (immunoPET) demonstrated high uptake in tumour lesions with high PD-L1 expression. The use of immunoPET could therefore help identify BCa patients who exhibit PD-L1 positive tumours for systemic immune-therapy.
PET/CT and PET/MRI seem to be promising imaging tools in BCa staging, especially for the detection of lymph node and distant metastases, as they are more accurate than conventional CT. Future clinical trials with novel radiopharmaceuticals and machine-learning driven PET-technologies bear the potential to help in the early detection, staging, monitoring and precision-medicine approach. Specifically, immunoPET is of high future interest, as it could help develop the concept of precision-medicine in the age of immunotherapy.
本研究旨在总结不同正电子发射断层扫描（PET）成像方式在膀胱癌（BCa）分期中的应用证据。我们进一步讨论了使用不同放射性药物的 PET/计算机断层扫描（CT）和 PET/磁共振成像（MRI）来对肿瘤生物学进行特征分析，以指导治疗。
现有证据支持 PET/CT 在 BCa 分期中的优势，因为与单独 CT 相比，其在检测淋巴结转移方面具有更高的准确性。由于 MRI 具有更高的软组织对比度，PET/MRI 的应用具有重要的未来意义，这可能使肿瘤在膀胱中的早期检测成为可能。就目前而言，当涉及到早期 BCa 的诊断时，PET/MRI 的敏感性仍然太低。这主要是由于常用的 [18F]FDG PET 示踪剂的肾排泄，因此膀胱壁的小病变可能会被遗漏。使用针对免疫检查点或其他免疫细胞靶点的 PET 放射性药物（免疫 PET）的新研究表明，在 PD-L1 高表达的肿瘤病变中摄取量很高。因此，免疫 PET 的使用可以帮助确定表现出 PD-L1 阳性肿瘤的 BCa 患者，以进行全身免疫治疗。
PET/CT 和 PET/MRI 似乎是 BCa 分期中很有前途的成像工具，特别是在检测淋巴结和远处转移方面，因为它们比传统 CT 更准确。使用新型放射性药物和基于机器学习的 PET 技术的未来临床试验有可能有助于早期检测、分期、监测和精准医学方法。特别是，免疫 PET 具有很高的未来意义，因为它可以帮助在免疫治疗时代发展精准医学的概念。
