Introduction

The diagnostic evaluation of men with suspected prostate cancer (PCa) yet inconclusive MRI (PI-RADS ≤ 3) presents a common clinical challenge. [⁶⁸Ga]Ga-labelled prostate-specific membrane antigen ([⁶⁸Ga]Ga-PSMA) positron emission tomography/computed tomography (PET/CT) has shown promise in identifying clinically significant PCa (csPCa). We aim to establish a diagnostic model incorporating PSMA-PET to enhance the diagnostic process of csPCa in PI-RADS ≤ 3 men.

Materials and Methods

This study retrospective included 151 men with clinical suspicion of PCa and PI-RADS ≤ 3 MRI. All men underwent [⁶⁸Ga]Ga-PSMA PET/CT scans and ultrasound/MRI/PET fusion-guided biopsies. csPCa was defined as Grade Group ≥ 2. PRIMARY-scores from PSMA-PET scans were evaluated. A diagnostic model incorporating PSMA-PET and prostate-specific antigen (PSA)-derived parameters was developed. The discriminative performance and clinical utility were compared with conventional methods. Internal validation was conducted using a fivefold cross-validation with 1000 iterations.

Results

In this PI-RADS ≤ 3 cohort, areas-under-the-curve (AUCs) for detecting csPCa were 0.796 (95%CI, 0.738–0.853), 0.851 (95%CI, 0.783–0.918) and 0.806 (95%CI, 0.742–0.870) for PRIMARY-score, SUVmax and routine clinical PSMA-PET assessment, respectively. The diagnostic model comprising PRIMARY-score, SUVmax and serum free PSA/total PSA (fPSA/tPSA) achieved a significantly higher AUC of 0.906 (95%CI, 0.851–0.961) compared to strategies based on PRIMARY-score or SUVmax (P < 0.05) and markedly superior to conventional strategies typically based on PSA density (P < 0.001). The average fivefold cross-validated AUC with 1000 iterations was 0.878 (95%CI, 0.820–0.954). Theoretically, using a threshold of 21.6%, the model could have prevented 78% of unnecessary biopsies while missing only 7.8% of csPCa cases in this cohort.

Conclusions

A novel diagnostic model incorporating PSMA-PET derived metrics—PRIMARY-score and SUVmax—along with serum fPSA/tPSA, has been developed and validated. The integrated model may assist clinical decision-making with enhanced diagnostic accuracy over the individual conventional metrics. It has great potential to reduce unnecessary biopsies for men with PI-RADS ≤ 3 MRI results and warrants further prospective and external evaluations.

中文翻译：

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使用基于 PSMA-PET 和 PSA 的新型模型来提高具有临床意义的前列腺癌的诊断准确性，并避免对 PI-RADS ≤ 3 MRI 男性进行不必要的活检

 介绍

疑似前列腺癌 （PCa） 但 MRI （PI-RADS ≤ 3） 的男性的诊断评估是一个常见的临床挑战。[⁶⁸加]Ga 标记的前列腺特异性膜抗原 （[⁶⁸Ga]Ga-PSMA） 正电子发射断层扫描/计算机断层扫描 （PET/CT） 在识别具有临床意义的 PCa （csPCa） 方面显示出前景。我们的目标是建立一个结合 PSMA-PET 的诊断模型，以增强 3 名男性 PI-RADS ≤ csPCa 的诊断过程。

 材料和方法

本研究回顾性研究纳入了 151 例临床疑似 PCa 和 PI-RADS ≤ 3 MRI 的男性。所有男性均接受了 [⁶⁸Ga]Ga-PSMA PET/CT 扫描和超声/MRI/PET 融合引导活检。csPCa 被定义为 2 ≥ 级组。评估 PSMA-PET 扫描的 PRIMARY 评分。开发了一种包含 PSMA-PET 和前列腺特异性抗原 （PSA） 衍生参数的诊断模型。将鉴别性能和临床效用与传统方法进行比较。内部验证使用具有 1000 次迭代的 5 倍交叉验证进行。

 结果

在这个 PI-RADS ≤ 3 队列中，检测 csPCa 的曲线下面积 （AUC） 分别为 0.796 （95% CI， 0.738–0.853）、0.851 （95% CI， 0.783–0.918） 和 0.806 （95% CI， 0.742–0.870） 对于主要评分、SUVmax 和常规临床 PSMA-PET 评估。与基于 PRIMARY 评分或 SUVmax 的策略相比，包括 PRIMARY 评分、SUVmax 和血清游离 PSA/总 PSA （fPSA/tPSA） 的诊断模型实现了 0.906 （95%CI，0.851–0.961） 的显著更高 AUC （P < 0.05），明显优于通常基于 PSA 密度的常规策略 （P < 0.001）。1000 次迭代的平均 5 倍交叉验证 AUC 为 0.878 （95% CI，0.820–0.954）。理论上，使用 21.6% 的阈值，该模型可以防止 78% 的不必要活检，同时在该队列中仅遗漏 7.8% 的 csPCa 病例。

 结论

已经开发并验证了一种新的诊断模型，该模型结合了 PSMA-PET 衍生指标 — PRIMARY-score 和 SUVmax — 以及血清 fPSA/tPSA。该集成模型可以帮助临床决策，提高对单个常规指标的诊断准确性。它对 PI-RADS 男性的 3 ≤ MRI 结果减少不必要的活检具有巨大潜力，并需要进一步的前瞻性和外部评估。