Head-to-Head Comparison of Fibroblast Activation Protein Inhibitors (FAPI) Radiotracers versus [18F]F-FDG in Oncology: A Systematic Review

Int J Mol Sci. 2021 Oct 17;22(20):11192. doi: 10.3390/ijms222011192.


Several recent studies comparing radiolabeled fibroblast activation protein inhibitors (FAPI) and fluorine-18 fluorodeoxyglucose ([18F]F-FDG) as positron emission tomography (PET) radiotracers in oncology have been published. The aim of this systematic review is to perform an updated evidence-based summary about the comparison of these PET radiotracers in oncology to better address further research in this setting. Studies or subsets of studies comparing radiolabeled FAPI and [18F]F-FDG as PET radiotracers in oncology were eligible for inclusion in this systematic review. A systematic literature search of PubMed/MEDLINE and Cochrane library databases was performed until August 2021. Literature data about the comparison of [18F]F-FDG and radiolabeled FAPI are rapidly increasing. Overall, taking into account radiotracer uptake and tumor-to-background uptake ratio, compared to [18F]F-FDG PET, an equal or higher detection of primary tumors and/or metastatic lesions was usually demonstrated by using radiolabeled FAPI PET. In particular, the cancer entities with better detection rate of tumor lesions by using radiolabeled FAPI PET, compared to [18F]F-FDG PET, were gastrointestinal tumors, liver tumors, breast cancer and nasopharyngeal carcinoma. Further comparison studies are needed to better evaluate the best field of application of radiolabeled FAPI PET.

Keywords: FAPI; FDG; PET; cancer; fibroblast activation protein; fluorodeoxyglucose; imaging; oncology; positron emission tomography; systematic review.

Publication types

  • Comparative Study
  • Systematic Review

MeSH terms

  • Endopeptidases
  • Fluorodeoxyglucose F18*
  • Gallium Radioisotopes
  • Heterocyclic Compounds, 1-Ring / chemistry
  • Heterocyclic Compounds, 1-Ring / pharmacology*
  • Humans
  • Medical Oncology
  • Membrane Proteins / antagonists & inhibitors*
  • Neoplasms / diagnostic imaging*
  • Positron Emission Tomography Computed Tomography / methods*


  • Gallium Radioisotopes
  • Heterocyclic Compounds, 1-Ring
  • Membrane Proteins
  • Fluorodeoxyglucose F18
  • 1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid
  • Gallium-68
  • Endopeptidases
  • fibroblast activation protein alpha