26urobay26 10.3205/26urobay26 urn:nbn:de:0183-26urobay266 Meeting Abstract Laukhtina Laukhtina Ekaterina E

Medical University of Vienna, Department of Urology, Vienna, Austria

author Shariat Shariat Shahrokh F. SF

Medical University of Vienna, Department of Urology, Vienna, Austria

author Hassler-Di Fratta Hassler-Di Fratta Melanie M

Medical University of Vienna, Department of Urology, Vienna, Austria

author Hacker Hacker Marcus M

Medical University of Vienna, Department of Biomedical Imaging and Image-guided Therapy, Devision of Nuclear Medicine, Vienna, Austria

author Muin Muin Dina D

Medical University of Vienna, Department of Biomedical Imaging and Image-guided Therapy, Devision of Nuclear Medicine, Vienna, Austria

author German Medical Science GMS Publishing House

Düsseldorf

610 20260506 engl This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. Dieser Artikel ist ein Open-Access-Artikel und steht unter den Lizenzbedingungen der Creative Commons Attribution 4.0 License (Namensnennung). M0645 26 Bayerische Urologenvereinigung Österreichische Gesellschaft für Urologie und Andrologie 52. Tagung der Bayerischen Urologenvereinigung und der Österreichischen Gesellschaft für Urologie und Andrologie Prostata-, Urothel- & Nierenzellkarzinom klinisch, operativ, systemisch, experimentell Würzburg 20260506 20260508 26urobay26 TextIntroduction: Fibroblast activation protein (FAP) is frequently overexpressed by cancer-associated fibroblasts in various tumor types, including bladder cancer. This study aimed to evaluate the performance of [68Ga]-FAPI-PET imaging for loco-regional staging in patients with MIBC. Methods: In this prospective investigator-initiated study, consecutive MIBC patients planned for RC were enrolled. All patients underwent both [68Ga]-FAPI-PET/MRI and standard [18F]-FDG-PET/CT prior to NAC and again prior to RC. The primary outcome of interest was the diagnostic accuracy of [68Ga]-FAPI-PET/MRI and/or [18F]-FDG-PET/CT for local and nodal staging in MIBC patients. The specificity, sensitivity, PPV, and NPV of imaging modalities for local and nodal staging were assessed, with pathology results at RC serving as the reference test. Results: We included twenty-two MIBC patients treated with RC; among them, fourteen (64%) received NAC. Fifteen patients (68%) had residual bladder tumor at RC. In ten patients, [68Ga]-FAPI demonstrated significant expression in the primary tumor located in the bladder wall, resulting in a sensitivity of 60%, specificity of 85%, PPV of 89%, and NPV of 50%. Similarly, [18F]-FDG-PET/CT demonstrated a sensitivity of 60%, specificity of 100%, PPV of 100%, and NPV of 54% for primary tumor detection. The median number of removed lymph nodes was 32 (range 2 to 78). Seven patients (32%) had lymph node metastases on the RC pathology report. For lymph node detection, [68Ga]-FAPI-PET/MRI and [18F]-FDG-PET/CT resulted in identical sensitivity (33%), specificity (93%), PPV(69%), and NPV (75%). Conclusion: In this study, [68Ga]-FAPI-PET/MRI demonstrated similar diagnostic accuracy to [18F]-FDG-PET/CT for locoregional tumor staging in MIBC patients; both modalities had a moderate sensitivity but high specificity for detecting primary tumors and lymph node metastases. These findings indicate that [68Ga]-FAPI-PET could be a viable alternative imaging tool for MIBC staging, though both imaging modalities/tracers underperform for ruling out a cancer. Further studies are needed to validate [68Ga]-FAPI-PET’s reliability and clinical utility. 0 0 0 0