Diagnostic accuracy of 18F-FDG PET/CT in muscle-invasive bladder cancer: rationale and design of the MIBC-PET study

Introduction: Muscle-invasive bladder cancer (MIBC) is associated with poor prognosis. Current staging relies on CT and MRI, but both show limited sensitivity for nodal and distant metastases. [18F]FDG PET/CT has emerged as a promising tool for staging and response assessment, yet its role remains undefined. Methods and analysis: MIBC-PET is a prospective, monocentric, no-profit study with paired imaging comparison enrolling 60 patients with newly diagnosed, histologically confirmed high-grade MIBC. All patients undergo baseline staging with [18F]FDG PET/CT and contrast-enhanced CT (ceCT) of chest, abdomen, and pelvis. A second [18F]FDG PET/CT and CT are performed after two cycles of neoadjuvant therapy. [18F]FDG PET/CT includes both standard delayed imaging and an early dynamic pelvic acquisition to overcome urinary tracer interference. The primary endpoints are (1) diagnostic accuracy of [18F]FDG PET/CT vs. ceCT for baseline staging, and (2) accuracy of [18F]FDG PET/CT in predicting pathological response to neoadjuvant chemotherapy. Secondary endpoints include validation of early dynamic [18F]FDG PET/CT for local staging and radiomic/AI-based predictive modeling. Ethics and dissemination: The study complies with the Declaration of Helsinki and Good Clinical Practice guidelines. The study was approved by the local ethical committee (CE-AVEC 109-2024-Oss-AOUFe – P.I. Dr. Luca Urso, MD). Results will inform the integration of [18F]FDG PET/CT into diagnostic algorithms for MIBC. Trial registration: ClinicalTrials.gov, identifier: not yet assigned. Local trial registration code: CE-AVEC 109-2024-Oss-AOUFe.