Purpose

To explore the dynamic and parametric characteristics of [¹⁸F]F-FAPI-42 PET/CT in lung cancers.

Methods

Nineteen participants with newly diagnosed lung cancer underwent 60-min dynamic [¹⁸F]F-FAPI-42 PET/CT. Time-activity curves (TAC) were generated for tumors and normal organs, with kinetic parameters (K₁, K₂, K₃, K₄, K_i) calculated. A new parameter, the K ratio (K₁ + K₃)/(K₂ + K₄), was introduced to measure net uptake efficiency.

Results

In primary tumor (PT), [¹⁸F]F-FAPI-42 uptake showed a gradual increase followed by a plateau, contrasting with organs like the thyroid and pancreas, which showed rapid uptake and continuous washout. Compared to non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC) lesions reached the plateau earlier (11 min vs. 14 min) but had a lower uptake. During the plateau phase, [¹⁸F]F-FAPI-42 demonstrated slight washout in SCLC, whereas its uptake increased slightly in NSCLC. Lymph node and distant metastases exhibited similar TAC profiles to primary tumors. Kinetic modeling revealed that an irreversible two-compartment model (irre-2TCM) best represented the pharmacokinetics of [¹⁸F]F-FAPI-42 in lung cancer, whereas re-2TCM was better suited for the pancreas and thyroid. Lower K₁, K₂, K₃ and K₄ were observed in PT compared to those in the pancreas and thyroid (P < 0.05), however, the K ratio in PT was found to be 2–3 times higher. SCLC had lower K_i and SUVmean than NSCLC (P < 0.05). Kinetic parameter differences were also observed between PT and metastatic lesions. Larger metastatic lymph nodes exhibited higher K₁, K_i, and K ratio than smaller ones.

Conclusion

Lung cancers exhibit distinct [¹⁸F]F-FAPI-42 dynamic and kinetic characteristics compared to the thyroid gland and pancreas. Differences were also observed between SCLC and NSCLC, primary and metastatic lesions, as well as larger versus smaller lesions. These findings provide valuable insights into the in vivo pharmacokinetics of [¹⁸F]F-FAPI-42, potentially improving the diagnosis of lung cancer.

Trial registration

ChiCTR2100045757. Registered April 24, 2021 retrospectively registered, http//www.chictr.org.cn.

中文翻译：

---

[18楼]F-FAPI-42 PET 动态成像特征和肺癌多参数定量：使用 uEXPLORER PET/CT 的探索性研究

 目的

探讨 [¹⁸F]F-FAPI-42 PET/CT 在肺癌中的动力学和参数特性。

 方法

19 名新诊断肺癌参与者接受了 60 分钟动态 [¹⁸F]F-FAPI-42 PET/CT。生成肿瘤和正常器官的时间活动曲线 （TAC），并计算动力学参数 （K₁、K₂、K₃、K₄、K）。引入了一个新参数 K 比 （K₁ + K₃）/（K₂ + K₄），用于测量净摄取效率。

 结果

在原发肿瘤 （PT） 中，[¹⁸F]F-FAPI-42 摄取显示逐渐增加，然后趋于稳定，与甲状腺和胰腺等器官形成鲜明对比，后者表现出快速摄取和持续洗脱。与非小细胞肺癌 （NSCLC） 相比，小细胞肺癌 （SCLC） 病灶更早到达平台期 （11 min vs. 14 min），但摄取率较低。在平台期，[¹⁸F]F-FAPI-42 在 SCLC 中表现出轻微的洗脱，而在 NSCLC 中其摄取略有增加。淋巴结和远处转移表现出与原发性肿瘤相似的 TAC 特征。动力学模型显示，不可逆的两室模型 （irre-2TCM） 最能代表 [¹⁸F]F-FAPI-42 在肺癌中的药代动力学，而 re-2TCM 更适合胰腺和甲状腺。与胰腺和甲状腺相比，在 PT 中观察到较低的 K₁、K₂、K₃ 和 K₄ （P < 0.05），然而，发现 PT 中的 K 比值高 2-3 倍。SCLC 的 K 和 SUV 平均值低于 NSCLC （P < 0.05）。在 PT 和转移病灶之间也观察到动力学参数差异。较大的转移性淋巴结比较小的转移性淋巴结表现出更高的 K₁ 、 K 和 K 比率。

 结论

与甲状腺和胰腺相比，肺癌表现出不同的 [¹⁸F]F-FAPI-42 动态和动力学特征。在 SCLC 和 NSCLC、原发性和转移性病灶以及较大与较小的病灶之间也观察到差异。这些发现为 [¹⁸F]F-FAPI-42 的体内药代动力学提供了有价值的见解，有可能改善肺癌的诊断。

 试用注册

ChiCTR2100045757。2021 年 4 月 24 日注册，追溯注册，http//www.chictr.org.cn。