68Ga-FAPI-04 vs. 18F-FDG in a longitudinal preclinical PET imaging of metastatic breast cancer.

Abstract

PURPOSE:

This longitudinal study aims to evaluate the performance of 68 Ga-FAPI-04 and 18F-FDG and to profile the dynamic process of tumor metastasis in a preclinical 4T1 breast cancer model. Although both of these two radioligands are wildly used in clinic, no study was reported on their performance in the longitudinal monitoring of tumor metastasis. Also, no correlation between the expression level of fibroblast activation protein (FAP) and the development of tumor metastasis has been elucidated previously. In this study, we evaluated the performance of 68 Ga-FAPI-04 and 18F-FDG PET during the entire process of tumor metastasis, and their potential for the early diagnosis of tumor metastasis. We also clarified the correlation of uptakes as well as the signal-to-background (S/B) ratios between these two probes at different stages of tumor metastasis.

METHODS:

Forty 4T1 metastatic breast cancer murine models were established using female BALB/c mice, followed by the longitudinal imaging with 68 Ga-FAPI-04 and 18F-FDG once a week for up to 6 weeks. In vitro hematoxylin and eosin (H&E) and immunochemistry (IHE) staining were performed to evaluate FAP expression on the metastatic lesions. Further statistical analysis was performed to evaluate the correlation of 68 Ga-FAPI-04 and 18F-FDG uptake (%ID/cc) at different stages of the metastasis.

RESULTS:

68 Ga-FPAI-04 holds an advantage over 18F-FDG with higher sensitivity at the early stage of tumor metastasis. However, with the progress of tumor metastasis, uptake of 68 Ga-FAPI-04 decreases and becomes less sensitive than 18F-FDG. There is also no direct correlation between uptake or S/B ratios of 68 Ga-FAPI-04 and 18F-FDG during this dynamic process.

CONCLUSION:

68 Ga-FAPI-04 is more sensitive than 18F-FDG in detecting the early stage of tumor metastasis, but becomes less sensitive than 18F-FDG at the late stage of tumor metastasis. We envision this result would be meaningful for the explanation of the 68 Ga-FAPI-04 and 18F-FDG imaging both in the future clinic and preclinic studies.

• Authors: Fan Ding, Chen Huang, Chenyi Liang, Cheng Wang, Jianjun Liu, Dewei Tang
• Journal: European journal of nuclear medicine and molecular imaging (Eur J Nucl Med Mol Imaging) Vol. 49 Issue 1 Pg. 290-300 (12 2021) ISSN: 1619-7089 [Electronic] Germany
• PMID: 34181060 (Publication Type: Journal Article)
• Copyright: © 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Chemical References

• 68Ga-FAPI
• Gallium Radioisotopes
• Quinolines
• Fluorodeoxyglucose F18

Topics

• Animals
• Female
• Fluorodeoxyglucose F18
• Gallium Radioisotopes
• Longitudinal Studies
• Mice
• Neoplasms
• Positron Emission Tomography Computed Tomography
• Positron-Emission Tomography
• Quinolines