Fibroblast Activation Protein Identifies Progressive Bladder Cancer and Allows Peritoneal Metastasis Detection by 68Ga-FAPI PET/CT Imaging – A Case Report

Bastiaan J. Viergever, Esther Strating, Marnix Lam, Onno Kranenburg and Richard P. Meijer

Abstract

Objective: Currently, [18F] FDG-PET/CT scans are used in advanced bladder cancer patients to identify metastatic lesions. Unfortunately, FDG-PET/CT displays relatively low sensitivity in detecting metastatic disease in these patients, resulting in open-and-close operations due to unexpected metastatic disease. Recently a novel radiotracer has emerged using FAP targeting [68Ga] FAPI-46, raising the question if this provides a more accurate alternative to [18F] FDG-PET/CT for detecting metastatic lesions in bladder cancer patients.
Methodology: FAP expression was assessed in primary and metastatic samples of two patients with MIBC using immunohistochemical analysis. Finally, both FDG and FAPI scans were obtained and compared using [18F] FDG-PET/CT and [68Ga] FAPI-46-PET/CT.
Results: FAP protein expression was found to be high in both primary and metastatic tumor lesions. In the primary tumor lesions, FAP expression was mainly observed in the fibrotic area adjacent to the tumor bulk. In contrast, PM showed FAP expression closely surrounding small tumor clusters. Finally, metastatic lesions that were undetectable on [18F] FDG-PET/CT were detected using [68Ga] FAPI-46-PET/CT. FAPI-46-PET/CT findings of PM correlated with lesions found in the open-and-close surgical procedures.
Conclusion: [68Ga] FAPI-46-PET/CT offers a promising additional tool to [18F] FDG-PET/CT for identifying peritoneal metastatic lesions of bladder cancer in high-risk patients.

Published on:  March 27, 2024
doi: 10.17756/micr.2024-102

Citation:  Viergever BJ, Strating E, Lam M, Kranenburg O, Meijer RP. 2024. Fibroblast Activation Protein Identifies Progressive Bladder Cancer and Allows Peritoneal Metastasis Detection by 68Ga-FAPI PET/CT Imaging – A Case Report. J Med Imaging Case Rep 8(1): 5-11.

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