The recent development of quinoline-based PET tracers that act as fibroblast-activation-protein inhibitors (FAPIs) demonstrated promising preclinical and clinical results. FAP is overexpressed by cancer-associated fibroblasts of several tumor entities. Here, we quantify the tumor uptake on (68)Ga-FAPI PET/CT of various primary and metastatic tumors to identify the most promising indications for future application. Methods: (68)Ga-FAPI PET/CT scans were requested by various referring physicians according to individual clinical indications that were considered insufficiently covered by (18)F-FDG PET/CT or other imaging modalities. All PET/CT was performed 1 h after injection of 122-312 MBq of (68)Ga-FAPI-04. We retrospectively identified 80 patients with histopathologically proven primary tumors or metastases or radiologically unequivocal metastatic lesions of histologically proven primary tumors. Tumor uptake was quantified by SUVmax and SUVmean (60% isocontour). Results: Eighty patients with 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 (68)Ga-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 varied across and within all tumor entities. Because of low background in muscle and blood pool (SUVmax < 2), the tumor-to-background contrast ratios were more than 3-fold in the intermediate and more than 6-fold in the high-intensity uptake group. Conclusion: Several highly prevalent cancers presented with remarkably high uptake and image contrast on (68)Ga-FAPI PET/CT. The high and rather selective tumor uptake may open up new applications for noninvasive tumor characterization, staging examinations, or radioligand therapy.
- Kratochwil, C.
- Flechsig, P.
- Lindner, T.
- Abderrahim, L.
- Altmann, A.
- Mier, W.
- Adeberg, S.
- Rathke, H.
- Rohrich, M.
- Winter, H.
- Plinkert, P. K.
- Marme, F.
- Lang, M.
- Kauczor, H. U.
- Jager, D.
- Debus, J.
- Haberkorn, U.
- Giesel, F. L.
Keywords
- Biological Transport
- *Gallium Radioisotopes
- Gelatinases/*antagonists & inhibitors
- Humans
- Membrane Proteins/*antagonists & inhibitors
- Neoplasm Metastasis
- Neoplasms/*diagnostic imaging/*metabolism
- *Positron Emission Tomography Computed Tomography
- Radioactive Tracers
- Serine Endopeptidases
- *fapi
- *pet/ct
- *breast cancer
- *colorectal cancer
- *lung cancer