[68 Ga]Ga-FAPI-46 PET/CT for locoregional lymph node staging in urothelial carcinoma of the bladder prior to cystectomy: initial experiences from a pilot analysis

• DOI: 10.1007/s00259-024-06595-z
• Publication Date: 2024-01-18T07:02:22Z
• Authors: Lena M. Unterrainer; Lennert Eismann; Simon Lindner; Franz-Josef Gilde...; Johannes Toms; Jozefina Casuscelli; Adrien Holzgreve; Sophie C. Kunte; Clemens C. Cyran; Paula Menold; Alexander Karl; Marcus Unterrainer; Stephan T. Ledderose; Christian G. Stief; Peter Bartenstein; Alexander Kretschmer; Gerald B. Schulz
• Keywords: 03 medical and health sciences; 0302 clinical medicine; Short Communication

Abstract Introduction [68 Ga]Ga-FAPI-46 PET/CT is a novel hybrid imaging method that previously showed additional diagnostic value in the assessment of distant urothelial carcinoma lesions. We hypothesized that patients with bladder cancer benefit from [68 Ga]Ga-FAPI-46 PET/CT prior to radical cystectomy for locoregional lymph node staging.

Materials and methods Eighteen patients underwent [68 Ga]Ga-FAPI-46 PET/CT for evaluation of lymph node (LN) status in predefined LN regions. Two hundred twenty-nine intraoperatively removed LN served as histopathological reference standard.

Results Urothelial carcinoma (UC) spread was found in ten LN in seven different regions (14.3%). Hereby, [68 Ga]Ga-FAPI-46 PET/CT was positive in four out of seven regions (57.1%) and showed significantly increased FAPI uptake compared to non-pathological regions. In the remaining three out of seven (42.9%) regions, [68 Ga]Ga-FAPI-46 PET/CT was rated negative since no pathological increased FAPI uptake was detected or the proximity of the urinary tract prevented a differentiation from physiological uptake. CT was inconspicuous in these three regions. In total, two FAP-positive LN regions were found without histopathological counterpart. Overall, sensitivity, specificity, positive predictive value, and negative predictive value were 57.1%, 95.2%, 66.7%, and 93.0% for PET imaging.

Conclusion In summary, this innovative [68 Ga]Ga-FAPI-46 PET/CT method showed high specificity and negative predictive value in patients with bladder UC with a future potential to optimize therapy planning.