Abstract
The recent development of quinoline based positron-emission-tomography (PET)-tracers that act as fibroblast-activation-protein inhibitors (FAPIs) demonstrated promising preclinical and clinical results. FAP is overexpressed by cancer associated fibroblasts (CAFs) of several tumor entities. Here we quantify the tumor-uptake in FAPI-PET/CT of various primary and metastatic tumors to identify the most promising indications for future application. Methods: FAPI-PET/CTs were requested by various referring physicians according to individual clinical indications which were considered insufficiently covered by FDG-PET/CT or other imaging modalities. All PET/CTs were performed 1h after injection of 122-312 MBq 68Ga-FAPI-04. We retrospectively identified 80 patients with histopathological proven primary tumors or metastases or radiologically unequivocal metastatic lesions of histological proven primary tumors. Tumor uptake was quantified by SUVmax and SUVmean (60% isocontour). Results: 80 patients of 28 different tumor entities (54 primary tumors and 229 metastases) were evaluated. The highest average SUVmax (>12) was found in sarcoma, esophageal, breast, cholangiocarcinoma and lung cancer. The lowest FAPI uptake (average SUVmax <6) was observed in pheochromocytoma, renal cell, differentiated thyroid, adenoid-cystic and gastric cancer. The average SUVmax of hepatocellular, colorectal, head-neck, ovarian, pancreatic and prostate cancer was intermediate (SUV 6-12). SUV varies across and within all tumor entities. Due to low background in muscle and blood-pool (SUVmax < 2), the tumor-to-background contrast ratios are > 3-fold in the intermediate and > 6-fold in the high intensity uptake group. Conclusion: Several highly prevalent cancers presented with remarkably high uptake and image contrast in FAPI-PET/CT. The high and rather selective tumor uptake may open up new applications for non-invasive tumor-characterization, staging exams or radio-ligand therapy.
- Molecular Biology
- Molecular Imaging
- Oncology: Breast
- Oncology: Endocrine
- Oncology: General
- Oncology: GI
- Oncology: GYN
- Oncology: GU
- Oncology: Head and neck
- Oncology: Liver
- Oncology: Lung
- Oncology: Pancreas
- PET
- PET/CT
- PET/MRI
- Radiopharmaceuticals
- breast cancer
- colorectal cancer
- lung cancer
- ovarian cancer
- pancreatic cancer
- Copyright © 2019 by the Society of Nuclear Medicine and Molecular Imaging, Inc.