Diuretic-Enhanced Dual-Phase F-18 FDG PET/CT: A New Window Into Muscle-Invasive Bladder Cancer.

OBJECTIVE: This study aimed to assess the diagnostic performance of diuretic-enhanced dual-phase F-18 FDG PET/CT in detecting muscle invasion in bladder cancer (BC) and to evaluate the predictive role of metabolic and volumetric PET parameters. METHODS: A total of 105 patients (85 males, 20 females; mean age: 67.8 years) with suspected BC underwent F-18 FDG PET/CT for initial staging. Routine and delayed pelvic imaging was performed after intravenous furosemide. Metabolic and volumetric parameters, including SUV max , SUV mean , metabolic tumor volume (MTV), and total lesion glycolysis (TLG), were measured and correlated with histopathological findings. Statistical analyses consisted of Mann-Whitney U, Kruskal-Wallis, and Receiver operating characteristic (ROC) curve analysis. RESULTS: Distant metastases were detected in 30 patients (28.5%), which directly influenced treatment decisions. In the TUR-B cohort ( n  = 75), F-18 FDG PET/CT demonstrated a sensitivity of 78.0%, specificity of 62.5%, positive predictive value of 88.5%, negative predictive value of 43.5%, and an overall accuracy of 74.7% in differentiating malignant from benign bladder lesions. Among the 59 patients with confirmed malignancy, volumetric parameters correlated with pathological T-stage. Patients with T2 tumors had significantly higher SUV max , SUV mean , MTV, and TLG values compared with <T2 tumors ( p  < 0.001). ROC analysis confirmed the discriminative value of MTV (AUC: 0.814) and TLG (AUC: 0.830), with reliable cutoff values identified. CONCLUSION: Diuretic-enhanced dual-phase F-18 FDG PET/CT provides clinically valuable information for the assessment of detrusor muscle invasion and the differentiation of bladder lesions. Quantitative volumetric and metabolic parameters may serve as surrogate biomarkers, supporting preoperative staging and contributing to more precise, personalized treatment strategies for patients with BC.