The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Department of Nuclear Medicine, Qilu Hospital, Shandong University, Jinan City, Shandong Province, China.
Mol Imaging Biol. 2020 Feb;22(1):181-189. doi: 10.1007/s11307-019-01376-9.
Prostate-specific membrane antigen (PSMA)-targeted positron emission tomography (PET) imaging has impacted the management of patients with prostate cancer (PCa) in many parts of the world. PSMA-targeted endoradiotherapies are also being increasingly utilized and for these applications, the radiopharmaceutical distribution in normal organs is particularly important because it may limit the dose that can be delivered to tumors. In this study, we measured both interpatient and intrapatient variability of [F]DCFPyL uptake in the most relevant normal organs.
Baseline and 6-month follow-up PSMA-targeted [F]DCFPyL PET/computed tomography (CT) scans from 39 patients with PCa were reviewed. Volumes of interest were manually drawn using the best visual approximation of the organ edge for both lacrimal glands, all four major salivary glands, the liver, the spleen, and both kidneys for all patients. The average SUV, the COVs, and intraclass correlation coefficients (ICCs) across scans were calculated. Bland-Altman analyses were performed for all organs to derive repeatability coefficients (RCs).
The liver demonstrated the lowest interpatient variability (13.0 and 16.6 % at baseline and follow-up, respectively), while the spleen demonstrated the largest interpatient variability (44.6 and 51.0 % at baseline and follow-up, respectively). The lowest intrapatient variability was found in the spleen (ICC 0.86) while the highest intrapatient variability was in the kidneys (ICCs 0.40-0.50). Bland-Altman analyses showed 95 % repeatability coefficients for mean uptake > 40 % for multiple organs and were highest for the lacrimal glands, kidneys, and spleen.
Normal organs demonstrate significant variability in uptake of the PSMA-targeted radiotracer [F]DCFPyL. Depending on the organ, different contributions of interpatient and intrapatient factors affect the intrinsic variability. The RCs also vary significantly among the different organs were highest for the lacrimal glands, kidneys, and spleen. These findings may have important implications for the design of clinical protocols and personalized dosimetry for PSMA-targeted endoradiotherapies.
前列腺特异性膜抗原（PSMA）靶向正电子发射断层扫描（PET）成像已在世界许多地区影响了前列腺癌（PCa）患者的治疗管理。PSMA 靶向的内放射治疗也在越来越多地被应用，对于这些应用，放射性药物在正常器官中的分布尤其重要，因为它可能限制可以递送至肿瘤的剂量。在这项研究中，我们测量了最相关的正常器官中 [F]DCFPyL 摄取的患者间和患者内变异性。
回顾了 39 例 PCa 患者的基线和 6 个月随访的 PSMA 靶向 [F]DCFPyL PET/计算机断层扫描（CT）扫描。使用最佳视觉近似器官边缘手动绘制泪腺、所有四个主要唾液腺、肝脏、脾脏和两个肾脏的感兴趣容积。计算了所有扫描的平均 SUV、COV 和内类相关系数（ICC）。对所有器官进行 Bland-Altman 分析以得出可重复性系数（RC）。
肝脏显示出最低的患者间变异性（基线和随访时分别为 13.0%和 16.6%），而脾脏显示出最大的患者间变异性（基线和随访时分别为 44.6%和 51.0%）。脾脏的患者内变异性最低（ICC 0.86），而肾脏的患者内变异性最高（ICC 0.40-0.50）。Bland-Altman 分析显示，对于多个器官，95%的摄取平均值>40%的可重复性系数，泪腺、肾脏和脾脏的最高。
正常器官对 PSMA 靶向放射性示踪剂 [F]DCFPyL 的摄取表现出显著的变异性。根据器官的不同，患者间和患者内因素的不同贡献会影响内在变异性。不同器官的 RC 也有显著差异，泪腺、肾脏和脾脏的最高。这些发现可能对 PSMA 靶向内放射治疗的临床方案设计和个体化剂量学具有重要意义。
