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Introduction: Metastatic progression of bladder cancer significantly affects prognosis and treatment pathways. Traditional clinical staging with transurethral tumor resection and CT imaging frequently underestimates the extent of disease. This study evaluates the diagnostic efficacy of FDG-PET in staging bladder cancer.
Materials & Methods: Of 110 patients with advanced bladder cancer undergoing PET/CT surveillance from 2008-2012, 30 underwent PET/CT immediately prior to either radical cystectomy or percutaneous biopsy. CT images were examined for metastatic disease defined as lymph nodes ≥1.0cm, lung nodules ≥5mm or any bone/solid organ lesions. FDG-PET images obtained during the same imaging sequence were subsequently reviewed for increased FDG uptake. Positive imaging results were quantitatively analyzed against histopathologic specimens.
Results: 30 patients underwent staging FDG-PET/CT, of which 17 (57%) had N0M0 disease by TNM staging versus 13 (43%) with ≥N1 or M1 pathology identified in tissue specimens [Table 1]. CT alone showed a sensitivity of 61.5% and a specificity of 88.2%. The positive predictive value (PPV) for CT was 80.0% and negative predictive value (NPV) was 75.0%. Meanwhile PET/CT showed a sensitivity of 69.2% and specificity of 100% as well as a PPV of 100% and NPV 81.0%.
Conclusions: PET/CT imaging in bladder cancer may improve preoperative staging with fewer false positives that could inappropriately delay surgery. Our preliminary findings support further investigation of PET/CT as an accurate staging modality for bladder cancer.

Table 1.

	Path ≥N1 or M1 (N=13)	Path N0M0 (N=17)
PET + (N=9)	9	0
PET - (N=21)	4	17
CT + (N=10)	8	2
CT - (N=20)	5	15