Ahmanson Translational Theranostics Division, Department of Molecular & Medical Pharmacology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA.
Nuclear Medicine, Centre de recherche du Centre Hospitalier de l'Université de Montréal, Université de Montréal, Montréal, Québec, Canada.
Eur J Nucl Med Mol Imaging. 2024 Sep;51(11):3373-3385. doi: 10.1007/s00259-024-06733-7. Epub 2024 May 16.
Fibroblast activation protein (FAP)-inhibitor (FAPI)-PET tracers allow imaging of the FAP-expressing cancer associated fibroblasts (CAF) and also the normal activated fibroblasts (NAF) involved in inflammation/fibrosis that may be present after invasive medical interventions. We evaluated [68Ga]Ga-FAPI-46 uptake patterns post-medical/invasive non-systemic interventions.
This single-center retrospective analysis was conducted in 79 consecutive patients who underwent [Ga]Ga-FAPI-46 PET/CT. Investigators reviewed prior patient medical/invasive interventions (surgery, endoscopy, biopsy, radiotherapy, foreign body placement (FBP) defined as implanted medical/surgical material present at time of scan) and characterized the anatomically corresponding FAPI uptake intensity both visually (positive if above surrounding background) and quantitatively (SUVmax). Interventions with missing data/images or confounders of [Ga]Ga-FAPI-46 uptake (partial volume effect, other cause of increased uptake) were excluded. Available correlative FDG, DOTATATE and PSMA PET/CTs were analyzed when available.
163 medical/invasive interventions (mostly surgeries (49%), endoscopies (18%) and non-surgical biopsies (10%)) in 60 subjects were included for analysis. 43/163 (26%) involved FBP. FAPI uptake occurred in 24/163 (15%) of interventions (average SUVmax 3.2 (mild), range 1.5-5.1). The median time-interval post-intervention to FAPI-PET was 47.5 months and was shorter when FAPI uptake was present (median 9.5 months) than when absent (median 60.1 months; p = 0.001). Cut-off time beyond which no FAPI uptake would be present post-intervention without FBP was 8.2 months, with a sensitivity, specificity, positive predictive value and negative predictive value of 82, 90, 99 and 31% respectively. No optimal cutoff point could be determined when considering interventions with FBP. No significant difference was detected between frequency of [Ga]Ga-FAPI-46 and [F]FDG uptake in intervention sites. Compared to [Ga]Ga-PSMA-11, [Ga]Ga-FAPI-46 revealed more frequent and intense post-interventional tracer uptake.
[Ga]Ga-FAPI-46 uptake from medical/invasive interventions without FBP appears to be time dependent, nearly always absent beyond 8 months post-intervention, but frequently present for years with FBP.
成纤维细胞激活蛋白（FAP）抑制剂（FAPI）-PET 示踪剂可用于成像表达 FAP 的癌相关成纤维细胞（CAF），以及与侵入性医疗干预后可能存在的炎症/纤维化相关的正常激活成纤维细胞（NAF）。我们评估了[68Ga]Ga-FAPI-46 在非系统性医疗/侵入性干预后的摄取模式。
这是一项在 79 例连续接受[Ga]Ga-FAPI-46 PET/CT 的患者中进行的单中心回顾性分析。研究人员回顾了先前的患者医疗/侵入性干预（手术、内窥镜检查、活检、放疗、异物植入（FBP），定义为在扫描时存在的植入的医疗/外科材料），并根据视觉（高于周围背景为阳性）和定量（SUVmax）来描述解剖学上相应的 FAPI 摄取强度。排除了缺乏数据/图像的干预或[Ga]Ga-FAPI-46 摄取的混杂因素（部分容积效应、其他摄取增加的原因）。当有可用的相关 FDG、DOTATATE 和 PSMA PET/CT 时，也对其进行了分析。
在 60 名患者中，共有 163 次医疗/侵入性干预（主要为手术（49%）、内窥镜检查（18%）和非手术性活检（10%））被纳入分析。其中 43/163（26%）涉及 FBP。在 24/163（15%）次干预中观察到 FAPI 摄取（平均 SUVmax 为 3.2（轻度），范围为 1.5-5.1）。干预后至 FAPI-PET 的中位时间间隔为 47.5 个月，当存在 FAPI 摄取时（中位 9.5 个月）短于不存在时（中位 60.1 个月；p=0.001）。在没有 FBP 的情况下，干预后不再存在 FAPI 摄取的无摄取时间截断值为 8.2 个月，其灵敏度、特异性、阳性预测值和阴性预测值分别为 82%、90%、99%和 31%。当考虑有 FBP 的干预时，无法确定最佳截断值。在干预部位中，[Ga]Ga-FAPI-46 和[F]FDG 的摄取频率之间未检测到显著差异。与[Ga]Ga-PSMA-11 相比，[Ga]Ga-FAPI-46 显示出更频繁和强烈的干预后示踪剂摄取。
在没有 FBP 的医疗/侵入性干预后，[Ga]Ga-FAPI-46 的摄取似乎与时间有关，几乎总是在干预后 8 个月以上不再存在，但在存在 FBP 的情况下，摄取可能持续多年。
