Abstract：
Quantitative evaluation of prostate-specific membrane antigen (PSMA)-targeting PET/CT remains challenging but is urgently needed for the use of standardized PET-based response criteria, such as the PSMA PET/CT consensus statement or Response Evaluation Criteria in PSMA PET/CT (RECIP 1.0). A recent study evaluated the prognostic value of whole-body tumor volume using a semiautomatic method relying on a 50% threshold of lesion SUVmax (PSMATV50). In the present study, we analyzed the suitability of this approach comparing 18F-PSMA-1007 with 68Ga-PSMA-11 PET/CT scans and the potential of PSMATV50 for the prediction of overall survival (OS) in patients before 177Lu-PSMA radioligand therapy (RLT). Moreover, PSMATV50 was integrated into the PSMA PET/CT consensus statement as well as RECIP 1.0, and the prognostic value of these response classification systems was compared. Methods: This retrospective study included 70 patients with metastatic castration-resistant prostate cancer undergoing PSMA RLT. Thirty-three patients were monitored by 68Ga-PSMA-11 PET/CT, and 37 patients by 18F-PSMA-1007 PET/CT. PET/CT scans before (baseline) and at the end of PSMA RLT after 2-4 cycles (follow-up) were separately analyzed by 2 readers. PSMATV50 at baseline and its change at the time of follow-up (ΔPSMATV50, expressed as a ratio) were correlated with OS using Cox proportional-hazards regression. The results of both subgroups were compared. The integration of ΔPSMATV50 in existing response classification systems was evaluated. To assess and compare the discriminatory strength of these classification systems, Gönen and Heller concordance probability estimates were calculated. Results: PSMATV50 determination was technically feasible in all examinations. A higher PSMATV50 at baseline and a higher ΔPSMATV50 were strongly associated with a shorter OS for both 68Ga-PSMA-11 (PSMATV50: hazard ratio [HR] of 1.29 [95% CI, 1.05-1.55], P = 0.009; ΔPSMATV50: HR of 1.83 [95% CI, 1.08-3.09], P = 0.024) and 18F-PSMA-1007 (PSMATV50: HR of 1.84 [95% CI, 1.13-2.99], P = 0.014; ΔPSMATV50: HR of 1.23 [95% CI, 1.04-1.51], P = 0.03). Response assessment provided high discriminatory power for OS for the PSMA PET/CT consensus statement (concordance probability estimate, 0.73) as well as RECIP 1.0 (concordance probability estimate, 0.74). Conclusion: PSMATV50 and ΔPSMATV50 proved to be predictive of OS not only for 68Ga-PSMA-11 but also for 18F-PSMA-1007 PET/CT scans. Subsequent integration of ΔPSMATV50 into the PSMA PET/CT consensus statement and RECIP 1.0 provided equally high prognostic value for both classification systems.
摘要：
简介：前列腺特异性膜抗原（PSMA）-靶向正电子发射断层扫描/计算机断层扫描（PSMAPET/CT）的定量评估仍然具有挑战性，但迫切需要使用基于PET的标准化反应标准。如PSMAPET/CT共识声明或RECIP1.0。最近的一项研究使用半自动方法评估了全身肿瘤体积的预后价值，该方法依赖于最大病变标准化摄取值（PSMATV50）的50％阈值。在本研究中,我们分析了该方法比较18F-PSMA-1007和68Ga-PSMA-11PET/CT扫描的适用性,以及PSMATV50对177Lu-PSMA-放射性配体治疗(PSMARLT)前患者总生存期(OS)的预测潜力.此外，将PSMATV50整合到PSMAPET/CT共识声明以及RECIP1.0中，并比较了这些反应分类系统的预后价值。方法：这项回顾性研究包括70例接受PSMARLT的转移性去势抵抗性前列腺癌患者。33例患者通过68Ga-PSMA-11PET/CT监测，37例患者通过18F-PSMA-1007PET/CT监测。在2-4个周期（随访）后，PSMARLT之前（基线）和结束时的PET/CT扫描分别由两名读者进行分析。使用Cox比例风险回归将基线时的PSMATV50及其对随访的变化（ΔPSMATV50；表示为比率）与OS相关联。比较两个亚组的结果。评估了ΔPSMATV50在现有反应分类系统中的积分。为了评估和比较这些分类系统的歧视强度，计算了Gönen&Heller一致性概率估计(CPE)。结果：在所有检查中，PSMATV50测定在技术上是可行的。较高的PSMATV50基线和较高的ΔPSMATV50与68Ga-PSMA-11的较短OS密切相关（PSMATV50：HR1.29[1.05-1.55]，p=0.009；ΔPSMATV50：HR1.83[1.08-3.09]，p=0.024）和18F-PSMA-1007（PSMATV50：HR1.84[1.13-2.99]，p=0.014；ΔPSMATV50：HR1.23[1.04-1.51]，p=0.03)。响应评估为PSMAPET/CT共识声明（CPE0.73）和RECIP1.0（CPE0.74）的OS提供了很高的辨别能力。结论：PSMATV50和ΔPSMATV50不仅可以预测68Ga-PSMA-11的OS，而且可以预测18F-PSMA-1007PET/CT扫描的OS。随后将ΔPSMATV50整合到PSMAPET/CT共识声明和RECIP1.0中，为两种分类系统提供了同样高的预后价值。
